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Chuanneng Power Co., Ltd.: The main road works of the mine road of Lijiagou Mining and Dressing Project have been fully completed _ mining industry _ site _ conditions

Original title: Chuanneng Power: The main road works of the mine road of Lijiagou Mining and Dressing Project have been fully completed. According to the record of investor relations activities disclosed by Chuanneng Power on July 15, by the end of April 2022, the main road project of Lijiagou Mining and Dressing Project had been completed in an all-round way, with double-bridge vehicle traffic conditions to meet the needs of mine construction. A total of 7308 meters have been excavated, Mining Drilling Equipment , 43% of the excavation volume has been completed, and the excavation has reached the central position of No. I ore body in the center of the mining area, which has met the conditions for capital construction. The mining and beneficiation project has completed the earthwork transportation of the mining industrial site and the earthwork excavation and transportation of the crushing and grinding industrial site, and is carrying out the piling of the grinding foundation and the drilling of the flotation industrial site. At present, as the project is located in the plateau area, the local winter climate has a certain impact on the surface works, and the overall progress of the project is normal. Dingsheng Lithium Industry currently has an annual production capacity of 15000 tons of lithium salt, including 10000 tons of lithium carbonate and 5000 tons of lithium hydroxide. Return to Sohu to see more Responsible Editor: (function() { function getBrandHtml() { var brands = [],dth hammer bit, html = ''; for(var i = 0; i < brands.length; i++) { var brand = brands[i]; if(brands.length i+1) { html+= ''+brand.name+''; } else { html+= ''+brand.name+'、'; } } return html; }; if(document.getElementById('linkBtn')){ document.getElementById('linkBtn').onclick = function() { $('#brands').removeClass('brand');$ ( '# tipInfo').text ( 'Real name responded'); $ ('#linkBtn').remove();$ ('.real-response .content').css('line-height', '20px');$ ('.real-response .time').css('line-height', '20px'); }; document.getElementById('brands').innerHTML = getBrandHtml(); }; })();。 wt-dthtools.com


13/09/2022
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To understand the advanced support of tunnel pipe shed at one time, there are too many detailed words, so you need to collect them first! _ Reinforcement

Original title: Understand the advanced support of tunnel pipe shed at one time. There are too many detailed words. You need to collect them first! Source: Zhulong Forum Copyright belongs to the original author. As an auxiliary method of tunnel excavation, pipe-roof advanced support technology plays an important role in preventing tunnel landslide, inhibiting stratum displacement and controlling surface subsidence. Today, let's learn in detail what should be paid attention to in this tunnel construction technology! Advance support method for underground engineering Advance support technology refers to the technology that before tunnel excavation, an arched continuum is formed on the cross section of the tunnel by grouting, freezing, driving steel pipes, steel plates, anchor rods and other technical measures into the stratum in front of the tunnel face to reinforce the stratum in front of the excavation face, and at the same time, its supporting force is used to maintain the stability of the soil in front and reduce the surface settlement. The research shows that the grouting reinforcement can improve the strength and deformation modulus of the surrounding rock, and fundamentally improve the deformation law of the surrounding rock. The data show that the strength of sandstone can be increased by 50% -70% after grouting, siltstone and argillaceous rock can be increased by 2-4 times, and the increase of rock strength can reduce the support load by 2/3-4/5. The practice shows that the advanced support system can effectively limit the ground subsidence and fully maintain the natural strata in a stable state during tunnel excavation. The Research shows that 30% -40% of the total subsidence of the ground and 40% -50% of the total subsidence of the underground stratum occur before the general support begins to work, and the advance support has a 30-35% inhibition effect on the ground subsidence and a 40% inhibition effect on the tunnel top stratum (vault) subsidence. Reinforcing the stratum in front of the tunnel face plays a very important role in inhibiting land subsidence. Advance support technology has been widely used in underground engineering construction as an auxiliary construction method to reinforce the stratum, stabilize the vault and tunnel face, and reduce the surface settlement. According to the influence of reinforcement measures on the characteristics of surrounding strata and stress distribution, the advance support can be divided into stratum improvement method and pre-support method. Stratum improvement method is a method to improve the characteristics of the stratum soil around the excavation face, which includes grouting, soil reinforcement, drainage and stratum freezing, etc. Pre-support method is a method to reinforce the surrounding rock in advance before tunnel excavation, so as to increase the self-stability of the surrounding rock and minimize the stress interference around the excavation face. Advanced support methods mainly include: pipe shed method, mechanical pre-cutting method, pre-lining method, horizontal jet grouting method, advanced small conduit method, advanced anchor method, freezing method and so on. Among them, pipe roof method, horizontal jet grouting method, small conduit method and other support methods also improve and reinforce the stratum. Pipe shed grouting support Expand the full text A group of steel pipes are driven into the stratum along the drilled holes outside the excavation contour, and are combined with the steel arch to form a strong scaffolding pre-supporting and reinforcing system to support the load from the upper part of the pipe shed, and grouting is pressurized into the stratum through the quincunx grouting holes of the steel pipes to reinforce the weak and broken stratum and improve the self-stability of the stratum. Pipe roof grouting is a long-distance advanced support method with long advanced distance and large rigidity, which is suitable for the stratum where the tunnel face can not be self-stabilized and contains water, and has good effect of controlling surface settlement and anti-seepage and water sealing, and has high requirements for construction technology. If the pipe roof grouting is combined with the small pipe supplementary grouting method, it can prevent the collapse of the triangular soil below the pipe roof in addition to the characteristics of the large pipe roof, and the effect of this combination of long and short pre-support is more ideal. Main functions and advantages of pipe shed support (1) Beam-arch effect: The pipe shed constructed in advance forms a beam structure with the tunnel face and the rear support as the fulcrum. The two form a shell-like structure surrounding the tunnel outline, which can effectively inhibit the loosening and collapse of surrounding rock. (2) Reinforcement effect: The grouting slurry is pressed into the surrounding rock cracks through the pipe wall holes, so that the loose rock mass is cemented and consolidated, thus improving the physical and mechanical properties of the weak surrounding rock, enhancing the self-supporting capacity of the surrounding rock, and achieving the purpose of reinforcing the weak surrounding rock around the steel pipe. (3) Annular groove effect: The propagation of explosion shock wave and the expansion of detonation gas generated by tunnel face blasting are reflected, absorbed or diffracted when they meet the dense annular holes and grooves in the pipe roof, which greatly reduces the damage degree and disturbance range of surrounding rock caused by reverse stretching wave. (4) Ensure the safety of construction: the support rigidity of the pipe roof is relatively large. In case of landslide during construction, the collapse debris will also fall on the rock debris on the upper part of the pipe roof, which will play a buffer role. Even if the pipe roof is unstable, its damage will be relatively slow. List of advance support method for tunnel According to the influence of reinforcement measures on the characteristics of surrounding strata and stress distribution, the advance support can be divided into stratum improvement method and pre-support method. Stratum improvement method is a method to improve the characteristics of the stratum soil around the excavation face, which includes grouting, soil reinforcement, drainage and stratum freezing, etc. Pre-support method is a method to reinforce the surrounding rock in advance before tunnel excavation, so as to increase the self-stability of the surrounding rock and minimize the stress interference around the excavation face. Advanced support methods mainly include: pipe shed method, mechanical pre-cutting method, pre-lining method, horizontal jet grouting method, advanced small conduit method, advanced anchor method, freezing method and so on. Among them, pipe roof method, horizontal jet grouting method, small conduit method and other support methods also improve and reinforce the stratum. Pipe shed grouting support A group of steel pipes are driven into the stratum along the drilled holes outside the excavation contour, and are combined with the steel arch to form a strong scaffolding pre-supporting and reinforcing system to support the load from the upper part of the pipe shed, and grouting is pressurized into the stratum through the quincunx grouting holes of the steel pipes to reinforce the weak and broken stratum and improve the self-stability of the stratum. Pipe roof grouting is a long-distance advanced support method with long advanced distance and large rigidity, which is suitable for the stratum where the tunnel face can not be self-stabilized and contains water, and has good effect of controlling surface settlement and anti-seepage and water sealing, and has high requirements for construction technology. If the pipe roof grouting is combined with the small pipe supplementary grouting method, in addition to the characteristics of the large pipe roof, it can prevent the collapse of the triangular soil below the pipe roof, and this combination of long and short pre-support effect is more ideal. Applicable scope of pipe shed support According to the construction practice at home and abroad and the actual cases of the application of pipe shed support in underground engineering in China at present, the pipe shed support can be applied to soft sandy soil strata, sandy gravel strata, expansive soft flow plastic and hard plastic silty clay strata. The support for the construction of underground structures with abundant geological and groundwater conditions, such as fissure developed rock mass, mud and water burst section, fault fracture zone, collapse section, broken soil and rock pile section, shallow buried and large bias pressure, and the support for the excavation of tunnel entrance and exit sections are also mostly used in the excavation of underground projects such as subway crossing urban areas. It can be used as an auxiliary method for building tunnels under existing buildings, highways,Borehole Drill Bits, railways and underground structures; As an auxiliary construction method for the construction of tunnel portal section and large-section tunnel, and as an auxiliary construction method for other construction, it is also commonly used for projects with special requirements for construction settlement, such as shallow-buried but not suitable for open-cut sections or shallow-buried tunnels, when there are buildings on the surface, or when the tunnel is close to underground structures. Design of pipe shed support The design parameters of pipe shed support mainly include: steel pipe diameter, length, spacing, elevation, horizontal lap length, steel frame spacing, grouting parameters, etc. When the strength and rigidity of the steel pipe need to be increased, the reinforcement cage can be set in the pipe and then filled with cement mortar. The Code for Construction of Railway Tunnels in China stipulates that the diameter of the steel pipe used for the pipe shed should be φ70-φ127mm; the distance between the centers of the steel pipes should be 2-3 times of the pipe diameter; the length of the pipe shed should be selected according to the stratum conditions and should not be less than 10m; and the overlapping length of two groups of longitudinal pipe sheds should be more than 3m. The parameters of pipe shed support can be determined according to the engineering analogy method and adjusted according to the actual situation during construction. Selection of pipe diameter The diameter of steel pipes in most projects is between φ50 and φ180mm. Some scholars classify the pipe shed support into small pipe shed and large pipe shed according to the pipe diameter. The diameter of small pipe shed is generally between φ30 and φ50mm, and the diameter of large pipe shed is between φ89 and φ159mm. Steel pipes of φ108 mm are often used in projects, and the circumferential spacing should not be more than 3-5 times the diameter. The selection of steel pipe for pipe shed is based on the calculation results and the analysis of technical and economic factors. For the soft stratum with high requirements for support conditions, φ127mm steel pipe should be selected. For the cohesive soil with high soil cohesion, φ89mm steel pipe can be selected. In most cases, φ108mm steel pipe is selected for the general soil layer. Determination of Circumferential Spacing of Steel Pipe in Pipe Roof The conventional method of equidistant setting of pipe shed along the tunnel excavation contour line is not scientific, and it should be designed reasonably according to different situations. The spacing of steel arch can be adjusted and selected within the range of 40-80 cm according to the looseness of the collapse body, the difficulty of excavation and the construction effect, and it needs to be densified under special circumstances. According to the summary and comparative analysis of the geological conditions, engineering section size, buried depth and other influencing factors of the engineering example, the following empirical conclusions are drawn, which can be used as the construction basis of underground engineering support: Pipe shed steel pipe diameter range is generally φ70-180mm, we can classify the pipe shed support into small pipe shed, medium pipe shed and large pipe shed according to the pipe diameter. The pipe diameter of the small pipe shed is generally within the range of φ32 ~ 50mm,dhd drill bit, and the steel pipe with the pipe diameter of φ42mm is mostly used. The pipe length is preferably 3.5-5m, the circumferential spacing is generally 0.3-0.4m, and the horizontal overlapping length is 1-1.5m. The pipe diameter of the middle pipe shed is generally in the range of φ50-φ89mm, the pipe length is generally not more than 20m, the circumferential spacing is generally 0.3-0.4m, and the horizontal overlapping length is 1-2m. φ89-φ159 mm steel pipe can be used for large pipe shed. The common pipe diameter is φ108 mm, and the pipe length should not exceed 40 m. The steel pipe is generally 4m or 6m long in sections and connected by screw threads. The length of screw threads is not less than 150 mm, and the circumferential spacing is generally not more than 3-5 times of the pipe diameter. Reasonable Determination of the Extrapolation Angle If the angle is too small, the far end of the pipe shed may droop into the tunnel excavation area and affect the later construction; on the contrary, if the angle is too large, the distance between the pipe shed and the excavation area will be too large, and the collapse of the triangular soil below the pipe shed will bring great difficulties to the excavation and support of the tunnel body. It should also be determined according to the space size of the drilling room of the pipe roof and the length of the drill rod. The external insertion angle of the small pipe shed is usually 5º-15º, that of the medium pipe shed is usually 2º-8º, and that of the long pipe shed is 1º-3º. Steel arch support is generally made of I-steel, or I-steel and grid steel frame are used at intervals, the spacing is generally not more than 1 meter, and encryption is required under special circumstances. Pipe shed layout form Door-type arrangement Full circumference arrangement and upper one side arrangement Pipe shed layout form Pipe shed construction process flow Drilling process Grouting process Hole forming method Commonly used construction methods include pipe ramming, pipe jacking, drilling, etc. However, the drilling method is the most commonly used hole-forming method at present. With the specialization of drilling equipment becoming more and more detailed, the special drilling rig for pipe shed emerges as the times require. However, the pipe roof drilling is nearly horizontal drilling, which is different from the exploration drilling in nature, and requires high accuracy of the drilling direction (spatial position). Once the hole deviation is found or the design allowable deviation is exceeded in the final hole measurement, it will cause serious consequences. Drilling method Down-the-hole hammer drilling with casing Saturn simultaneous casing drilling method "Neptune" simultaneous casing method Dth hammer drilling tools with casing can be divided into two categories according to whether the diameter of the drill bit can be changed: variable diameter drilling tools with casing and non-variable diameter drilling tools. At present, there are mainly single-eccentric variable-diameter simultaneous casing drilling tools, double (three) eccentric variable-diameter simultaneous casing drilling tools and radial variable-diameter simultaneous tubing drilling tools. Except for the single-eccentric variable-diameter simultaneous casing drilling tool, the bit variable-diameter simultaneous casing drilling tools of other structures belong to the concentric simultaneous casing drilling tool because the wing petals of the bit are symmetrical along the central axis of the drilling tool in the process of expansion and convergence. Both the inner and outer bit structure is adopted for the drilling tool with constant diameter and casing. Generally, the casing needs to be rotated. This kind of drilling tool belongs to the concentric drilling tool with casing. Relatively speaking, bit variable diameter simultaneous casing drilling tools are used in a large proportion, accounting for about 95% of the market, which is determined by its structural characteristics. Main defects of drill bit with constant diameter casing 1. When the drilling tool is working, the inner and outer pipes rotate at the same time, which is easy to cause the annular gap between the inner and outer pipes to be blocked by rock powder or stuck by large rock debris, resulting in the failure of the inner pipe to rotate reversely and the failure to separate the inner pipe from the outer pipe. This method requires a rotary drilling rig with large torque, which consumes a lot of energy and is not conducive to environmental protection; 2. Because the drill bit does not change the diameter of the casing drilling tool, it is very difficult to drill in the same diameter, especially when encountering boulders. Even if the drilling is successful, it is very troublesome to pull out the casing due to the shrinkage of the drilling hole, and even often causes accidents in the hole such as casing fracture. Turn head valve open Closure of head turning valve Single eccentric drill bit with casing-type I Open state Single eccentric drill bit with casing — Ⅱ type The advantage of this type of bit 1. The cross pin that connects the eccentric bit to the bit body only serves to suspend the bit It does not bear the torque, thus avoiding the accidents in the hole caused by the deformation and breakage of the pin; 2. At present, the eccentric casing bit used in China needs to be rotated. The expansion and contraction of the drill bit can be realized by about 175 degrees, and the diameter of the drill bit can be increased to the set reaming diameter by rotating the bit body of this type of drill bit forward by a very small angle (about 8 degrees), and when the drill bit is withdrawn, the diameter of the drilling bit can be reduced to the set diameter by rotating reversely by a very small angle, thereby reducing the probability of being stuck when the drilling bit is withdrawn; 3. Single eccentric casing bit The torque of type II is transmitted through the cooperation of a kidney-shaped oblong hole on the bit body and a kidney-shaped oblong shaft on the eccentric bit; 4. It is easy to realize larger reducing requirement. 。 Long screw drilling with casing Pipe shed borehole trajectory control method Once the hole deviation occurs or exceeds the design allowable deviation, it will hinder the drilling of adjacent steel pipes, resulting in uneven shape of the hole body and poor support effect. If the steel pipe sinks to a certain extent, it needs to be cut off during excavation, resulting in increased spacing and easy collapse. Therefore, medium pressure feeding, medium rotating speed and medium circulating fluid volume can be adopted during drilling; the radial error of the borehole plane shall be controlled within 20cm, and the angle error shall be less than 1 °, so as to avoid deflection and downward bending of the steel pipe of the pipe shed due to too large aperture. In the actual construction, it is generally difficult to avoid horizontal borehole bending, mining dth bit ,dth drilling hammer, so in addition to improving the positioning accuracy of the pipe roof, appropriate uplift (determined according to the geological conditions of the site) can be given to compensate for part of the borehole sag. Pipe shed borehole trajectory control method Once the hole deviation occurs or exceeds the design allowable deviation, it will hinder the drilling of adjacent steel pipes, resulting in uneven shape of the hole body and poor support effect. If the steel pipe sinks to a certain extent, it needs to be cut off during excavation, resulting in increased spacing and easy collapse. Therefore, medium pressure feeding, medium rotating speed and medium circulating fluid volume can be adopted during drilling; the radial error of the borehole plane shall be controlled within 20cm, and the angle error shall be less than 1 °, so as to avoid deflection and downward bending of the steel pipe of the pipe shed due to too large aperture. In the actual construction, it is generally difficult to avoid horizontal borehole bending, so in addition to improving the positioning accuracy of the pipe roof, appropriate uplift (determined according to the geological conditions of the site) can be given to compensate for part of the borehole sag. Grouting Pipe roof grouting is one of the key links in pipe roof construction, and the grouting effect also affects the construction quality of the whole pipe roof system. Therefore, the appropriate grout, pressure and reasonable flow should be selected according to the geological conditions. In the process of grouting, if the pressure is low, the grouting will not be able to enter, and if the pressure is too high, it will cause the ground to bulge and crack, which will affect the ground buildings in shallow urban areas. During grouting, low pressure and medium flow are generally adopted. During grouting, the pressure is gradually increased and the grouting flow is gradually reduced. When the pressure is increased to the final pressure, the grouting is continued for 5min, and then the grouting is finished. In order to ensure the construction quality, the in-situ grouting test should be carried out before the actual grouting construction to determine the optimal grouting parameters to guide the grouting and ensure the grouting effect under the conditions of the grout type and the expected grouting effect given in the design. In order to prevent hole collapse or grouting hole channeling, holes can be drilled at intervals during drilling, the distance between holes can be increased, and the connected holes can be drilled after the grouting is completed and solidified, so that the quality of drilling and grouting can be effectively ensured, the pipe shed and the grouting concrete can form a thick arch, and the bearing effect of longitudinal beam forming and transverse arch forming of the pipe shed can be realized. In order to reduce the mutual influence between adjacent pipe hole grouting, the grouting sequence is usually carried out from bottom to top and symmetrically from left to right; However, due to the mutual support of many block stones in the collapse body, there are many large cavities in the collapse body, some of which are directly connected with the collapse area. During grouting, the grout flows to the collapse area through these cavities under pressure, and can not diffuse evenly near the pipe shed, so that the grouting reinforcement zone can not be formed. Therefore, the intermittent grouting method is adopted according to experience. That is to say, when the grouting pressure does not come up for a long time, it means that the grout flows to the collapse area along the gap. At this time, the setting time of the grout is adjusted to 30-50 seconds. The grouting lasts for 1-5 minutes and stops for 40 seconds. After the original grout is initially set and thickened, the grouting is repeated. The original grout discharge channel is gradually reduced and finally blocked. The grout reaches the purpose of uniform diffusion around the pipe shed. Development Trend of Pipe Roof Advanced Support Technology In the current advanced support methods, there are mainly advanced bolt, advanced small pipe grouting and advanced pipe shed. Grouting with advance anchor and advance small pipe has the advantages of convenient construction, easy mastery of technology and low requirement of mechanized matching degree, but the support length is small (only 3 ~ 5 m), the distance of anchor or small pipe into the front sliding line of the working face is short, and the excavation cycle footage is limited. Generally, the cycle footage is controlled at 15 ~ 17 m in the shallow-buried loose strata, the number of cycles is increased, and the process exchange is frequent, especially in the surrounding rock with poor self-stability, the front end of the bolt and conduit is still in the sliding surface, which can not play the role of advanced support protection, and it is very easy to cause instability of the working face, and there is a greater security risk. Therefore, the application of long pipe shed is becoming more and more common. The support mechanism of the long pipe shed advance support construction technology is mainly the result of the joint action of the steel pipe and the grout consolidation body. On the one hand, drilling and setting down the steel pipe are carried out. When the steel pipe passes through the loose and weak surrounding rock, rock (soil) and other damage areas and extends into the undisturbed soil, it effectively guarantees the stability of the rock and soil mass on the excavation face. And on that other hand, grout is extrude from the holes of the steel floral tube through grouting. Under the action of a certain pressure, it is injected into the loose and weak strata around the steel pipe to form a composite and stable consolidation body, which changes the mechanical properties of the surrounding strata, strengthens the stability, and prevents soil collapse and surface subsidence. Pipe shed drilling rig produced in Italy DDL-300 drilling rig Diamond drilling and cemented carbide drilling in solid deposits. But also can be use for engineering geological exploration drill and foundation pile hole drilling. It is widely used in geological exploration, engineering exploration, anchoring protection, rotary jet grouting, pipe shed support and other engineering construction operations. Grouting construction case of advanced pipe shed The shallow-buried Class II surrounding rock section of the tunnel in this contract section is supported by advanced long pipe shed grouting, and the pipe shed is made of Φ108 mm steel pipe with a wall thickness of 4mm. The pipe shed is used in conjunction with the steel arch and passes through the belly of the arch. Pipe shed holes shall be drilled longitudinally on the arch along the tunnel excavation contour line, with the external insertion angle of about 3 °, so as not to intrude into the tunnel excavation line as small as possible. The hole diameter shall be 20 ~ 30 mm larger than the diameter of the pipe shed steel pipe, and the drilling sequence shall be from high hole position to low hole position. The front end of the steel pipe is processed into a sharp cone, and the tail is welded with a Φ10 stiffener for reinforcement. Φ12 mm grouting holes are arranged in quincunx shape on the part of the steel pipe entering the rock, and the spacing of the grouting holes is 15 cm. The direction of the steel pipe is parallel to the center line of the route, and the longitudinal overlapping length is greater than 1.5m. Tunnel construction process flow Surveying, setting out, drilling, charging, on-line blasting, ventilation, pumice removal, inverted arch loader loading of gangue (central ditch excavator loading of gangue), dump truck discharging of gangue construction system, bolt shotcreting 1. Main process flow (1) Drill and install grouting pipe. Cast C25 concrete protection arch outside the tunnel excavation contour line. Erect the drilling rig platform. Drill with the engineering horizontal drilling rig. After reaching the design depth, clean the hole. Install the grouting pipe. Install a rubber sleeve with the same diameter as the borehole at 1.5m ~ 2.5m of the orifice. Seal the orifice with cement mortar to prevent the slurry from extruding along the gap between the grouting pipe and the borehole wall. Drilling-grouting sequence shall be adopted for construction. (2) Prepare grouting liquid with superfine cement for slurry preparation and grouting. Adopt backward sectional grouting. Close the orifice valve and start the grouting pump for pipeline water pressure test. The test pressure is equal to the final grouting pressure. If there is water leakage, repair it in time. During grouting, low pressure and medium flow are adopted. During grouting, the pressure rises gradually and the flow decreases gradually. When the pressure rises to the final pressure, continue to inject for 5 minutes and then finish grouting. The grout in the grouting hole shall be removed in time after grouting and filled with No.30 cement mortar to enhance the rigidity and strength of the pipe shed. (3) Grouting completion standard: If the grouting construction of each section is normal, the grouting pressure reaches the designed final pressure, and the grouting amount reaches 80% or more of the designed grouting amount, or although the designed final pressure is not reached, but the grouting amount has reached the designed grouting amount, then the single-hole grouting can be completed. All the design grouting holes meet the completion standard, and there is no missing injection. The water absorption rate of the water injection test stratum is 0.05L/min. When the clay consolidation strength is greater than 0.4Mpa, the grouting of the whole section can be finished. 2. Construction of advanced small conduit Φ42mm seamless steel pipe with a wall thickness of 3.5mm shall be used as the advanced small conduit. Φ6 mm grouting holes are arranged in quincunx shape on the part of the steel pipe entering the rock, and the spacing of the grouting holes is 12 cm. The front end of the conduit is processed into a sharp cone, and the tail is welded with a Φ6.5 stiffener for reinforcement. Hydraulic grouting machine shall be selected. During construction, firstly use instruments to measure and set out, draw the excavation contour line, and determine the position of the center line of the small conduit. When the conduit is drilled, the depth of the hole shall be greater than the length of the conduit; when hammering or drilling is used for jacking, the jacking length shall not be less than 90% of the length of the conduit. Hydraulic grouting machine is used for grouting. Before grouting, shotcrete shall be sprayed to seal the working surface to prevent mortar leakage, and the thickness of the shotcrete layer shall not be less than 5cm. During the grouting of the conduit, the sealing plug shall be set at the tail. During the grouting of cement slurry, the grouting hole and vent hole shall be set on the sealing plug. During grouting, the grouting shall be stopped immediately after the grout is discharged from the vent hole. 3. Anchor rod construction 1) φ22 mortar advanced anchor bolt The hole position shall be determined and marked according to the design requirements and surrounding rock conditions before drilling the anchor bolt. The drilling hole shall be round and straight, and the hole diameter and depth shall meet the design requirements. The accumulated water and rock powder in the hole shall be blown clean. The rock surface of the anchor bolt orifice shall be leveled, and the rock surface shall be perpendicular to the drilling direction. If it is not perpendicular, it can be adjusted with a special backing plate when installing the anchor bolt, so that the backing plate is close to the rock surface. During the construction of anchor rod, the pre-tensioning force should be 50% ~ 80% of the anchoring force. After installation, it should be checked regularly and tightened in time if looseness is found. 2) D25 hollow grouting anchor bolt D25 hollow grouting system anchor bolt shall be used for various surrounding rock anchor bolts, with the length of 3.0 ~ 3.5m and quincunx layout. Use the pneumatic drill to drill the hole, after drilling to the specified depth, blow the hole with high-pressure air, drive in the anchor rod, and then use the grouting pump to fill the mortar from the middle hole of the anchor rod to the bottom of the hole, and install the base plate bolt. Key points and precautions for anchor rod construction ① The hole position shall be arranged according to the design, with the deviation less than 10 cm and the hole depth error of ± 10 cm. The diameter of the drill hole is 15 mm larger than the diameter of the anchor rod. The insertion length of anchor rod shall not be less than the design length. ② The borehole itself shall be straight and not bent. The direction is radial to the tunnel perimeter, but not parallel to the rock face. ③ During the construction of anchor rod, the positioning anchor rod of grid steel frame shall be embedded at the same time. After the anchor rod is inserted, it is not allowed to knock at will, and it is not allowed to hang heavy objects within three days. ④ Clean the hole before grouting, and use high-pressure air to remove the accumulated water, rock powder, debris and other sundries in the hole along the anchor rod hole. ⑤ The grouting tank and grouting pipe shall be used for grouting, and the orifice pressure shall be less than 0.4MPa. Grouting shall be carried out along the anchor bolt hole until grout flows out of the orifice. Mortar shall be ready for use, and shall be used up before the initial setting of mortar. ⑥ Three anchor rods shall be randomly sampled from every 100 anchor rods for pull-out test, so as to understand the anchoring quality of anchor rods. 4. Reinforcement mesh construction Reinforcement mesh shall be arranged for various surrounding rocks. Reinforcement mesh is made of φ6 round steel, with spacing of 5 cm × 15 cm. Reinforcement mesh is installed on site by single piece. The reinforcement mesh shall be firmly connected with the anchor rod and laid with the fluctuation of the shotcrete surface. The mesh reinforcement shall be firmly lapped with the mesh reinforcement of the sprayed concrete section, and the lapping length shall not be less than 200mm. The reinforcing mesh shall be firmly attached and shall not shake during shotcreting. 5. Construction of shotcrete (wet shotcrete) A. Design principle of shotcrete mix proportion When selecting the mix proportion of shotcrete, the requirements of concrete strength and other physical and mechanical properties as well as the requirements of shotcrete technology shall be considered. Cement, sand, gravel and various admixtures must meet the design and specification requirements. Design steps: determine the maximum particle size and sand ratio of aggregate, determine the amount of cement, determine the water-cement ratio and water consumption, determine the amount of sand and stone, adjust the trial spraying, and determine the construction mix proportion. B. Spray process flow: ① Inspection of raw materials: check the quality of various raw materials used, and use them only after they are qualified. ② Mechanical equipment inspection: technical inspection shall be carried out for the machinery, and test run shall be carried out for the water, air and circuit, and the equipment can be operated only after it is qualified. ③ Construction site inspection: inspect the surface to be sprayed, remove the dangerous rock and floating soil, sweep the rock surface with high-pressure air, and bury the thickness mark. C. Shotcrete sequence Shotcreting sequence: from bottom to top in the vertical direction, from left to right or from right to left in the horizontal direction, moving in a spiral track, pressing half a circle in one circle, and proceeding in order in the longitudinal direction. The rotation radius is generally 15 cm, and the length of each snaking is 3 ~ 4 m. When the rock surface is uneven, the concave part shall be leveled first. When spraying concrete, the speed of spraying concrete should not be too slow or too fast, and it should be adjusted in time. D. Spray quality inspection: check the spray surface for looseness, cracking, falling, slippage and other phenomena according to the specifications. If any, remove the re-spray in time. After the spray reaches a certain strength, the sound can be heard by hammering, and the hollowing and shelling can be treated in time. Drill and measure, and re-spray where the thickness is not enough. Timely measure the rebound rate and the actual mix proportion to guide the next construction. Carry out mechanical test on the spray body test piece. Detailed explanation of pictures of tunnel pipe shed construction process The difference between the advanced small conduit and the pipe shed: the treatment range of the advanced small conduit is generally about 6 meters. The small conduit is a steel pipe with a wall thickness of 5 mm and a diameter of 42 mm. It is a method to consolidate the relatively broken surrounding rock in front of the tunnel face by small pipe grouting, so that the surrounding rock can form a whole before the next step. The pipe shed is used when the geological conditions at the entrance of the tunnel are very poor (such as sandy soil, seriously broken rocks, loess, etc.). Generally, the length is about 20-30 meters. The pipe shed is a steel pipe with a wall thickness of 3.5mm and a diameter of 108mm. Of course,dth drill bits, the pipe shed can also be used when the geological conditions in the tunnel are very poor (for example, the length along the axis of the tunnel caused by roof fall in the tunnel is large, and the volume is large). Return to Sohu to see more Responsible Editor:. wt-dthtools.com


13/09/2022
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High risk but high salary! What is unknown behind the mysterious "construction site water ghost"? _ Drill Bit _ Work _ Engineering

Originally published as High risk but high salary! What is unknown behind the mysterious "construction site water ghost"? "It is said that this is a profession with high salary and high risk. If you come up, you will get 20,000 yuan. If you don't come up, you will get 1 million yuan." "You have to be a mother pulling a rope on the top before you dare to go down, not a daughter-in-law; or a father and son partner, husband and wife team is not safe, to avoid being framed by the people above." "Sign a statement of life and death beforehand, and life and death depend on fate and wealth." "If it really can't come up, the construction party will pour concrete directly into it, and even some project parties will deliberately bury the water ghost below, blood sacrifice to bless their project smoothly." …… The above rumors describe the "water ghost" of the construction site in a mysterious way! The work of "site water ghost" is basically to salvage drill bits underwater, because it needs to dive deep in the mud pit, so the risk factor is very high, so the name "site water ghost" is very famous. Water ghosts are not real ghosts. They are the name of professional divers on the construction site. They refer to people who are engaged in underwater work. They specialize in fishing out the head of the drill bit in the construction site, doing some underwater cutting or adjusting the drill pipe and other work. Note: The drill bit of this percussion drill may fall off. Water ghost is a high-risk occupation, such work has a high pay, some people think that as long as the courage is good enough to do, in fact, this is a wrong perception. Their work is so dangerous that if they are not careful, they will die. This work is much more dangerous than other diving operations. It is said that it is difficult to be a "water ghost on the construction site". Where is the difficulty? The main reasons are as follows: 1. The diving space is very narrow. The diameter of the drilling hole in the general construction site is between 80 CM and 2200 CM, which is the space they can dive into. When the water ghost dives under the hole, he needs to wear a heavy diving suit, and it is very difficult to turn around when working underwater. 2. The hole wall can collapse at any time. Because of the narrow diameter of the borehole, there will be a steel sleeve near the ground to prevent the hole from collapsing, but there is no steel sleeve below, and the whole hole is protected by mud. If you encounter a layer of soil or loose rock, the water ghost will rotate its body below, and the wall of the hole may collapse. Expand the full text 3. The medium that the water ghost enters is mud with zero visibility. We know that some mud is drilled out of the engineering borehole. The water and mud in the whole borehole are mixed together to become sticky mud. There is a lot of resistance to move forward in the mud. If you don't pay attention to it, the diving suit will be cut. 4. The depth of diving will not be too shallow. If the drill bit is lost in a shallow drilling hole, the construction site can be salvaged by itself. Generally, water ghosts are invited to salvage because the holes are too deep, some of them are more than ten meters, or even more than 20 meters. In addition, the density of mud is high, so the pressure of divers can be imagined. They have to work in such a dark environment. Under the holes, they rely on experience and construction records to explore. It is precisely because of this, the water ghost industry is very dangerous, not ordinary people can do it. Since it is so dangerous, why is there a water ghost industry? The original large-scale engineering construction,rock drilling tools, such as bridge construction, high-rise building construction is the need for piling, piling process is not foolproof, when the drill bit encounters complex geology, the drill bit of the impact drill may fall or be stuck, there is a pile driver drill anchor situation, at this time, the engineering side will often hire the water ghost to go down to salvage, The cost of salvage is not low, and it costs tens of thousands of yuan. Why do we have to fish the drill out? The drill bit of the pile driver is the most important part of the whole process when driving piles on a large construction site. The drill bit of the pile driver is divided into many forms, such as spiral drill bit and straight spiral drill bit. Among them, the conical double screw bit is suitable for hard rock, while the double screw bit is suitable for all kinds of frozen soil, weathered bedrock,mining drill bit, pebbles and other geology. The weight of the pile head of each pile driver is not light. Generally, it weighs several tons. The drill bit of cross and plum blossom generally weighs about three tons. The price of the drill bit is expensive. According to the size and function, the price ranges from 10,000 to tens of thousands of yuan. The drill bit of the pile driver is made of alloy, and a safety rope is tied on the drill bit when the pile is driven. It is very rare for a pile driver bit to fall off, but there are always accidents. If the drill bit of the pile driver falls off, the engineering side will try to fish it up, because if it is not fished up, the hole will be useless. To know the design of the project, the location of each pile has been repeatedly studied and verified. If the hole is abandoned, the redesign of another place will have a huge impact on the project. For large-scale projects such as road repair and bridge repair, changing a pile hole may affect the whole body. If the position of a pile foundation is changed, dozens of kilometers of boreholes may have to be redesigned and re-constructed. This will not only cost a lot of money, but also affect the progress of the project, the loss is incalculable. Besides, the price of a drill bit is not cheap. If it falls underground, if the engineering party does not salvage it, it needs to be replaced immediately. This is heavy and expensive, and it takes time to replace it, which also affects the progress of the project. Therefore, in the process of construction, if the drill bit of the pile driver falls, the engineering side will try to fish it out. In fact, every time the pile head falls, it is not necessary to ask the water ghost to salvage, the construction side can try to salvage by itself. The construction party will slowly try to hook up the drill bit with a hook, down the hole bit ,DHD Drill bit, because there is a circle of safety rope on the drill bit, if the hook can hook the circle of safety rope, it can be fished up. But the pile hole is often mud, water and mud mixed together, completely unable to see the underground situation, like a blind man touching the lamp. So how do the water ghosts salvage the drill bit? It turned out that in the process of salvage, two people were needed to cooperate. One person wore a protective suit, an oxygen mask, and a safety rope tied to his body. They dived into the sticky mud. It was dark in the mud, and nothing could be seen. They needed to dive tens of meters, or even hundreds of meters. At this time, danger is likely to occur, so a surface person is needed to ensure his safety. The security personnel standing outside the wellhead need to provide enough oxygen and air supply pressure for the diver. Because the more people sink, the greater the pressure of the water, underwater divers need a certain amount of air supply pressure to offset the impact of the surrounding water pressure, to ensure that they can smoothly dive to the downhole drill bit. When divers dive to the bottom of the pile hole, they will immediately report to the telephone operator or support personnel above through electronic equipment, and then ventilate to adapt to the underwater environment immediately. In fact, in the well, what they have to do is very simple, that is, take the rope and dive to the drill bit to tie the lifting point. As long as the steel cable can firmly bind the lifting point of the drill bit and pull it up, it is the matter of the machine. After finishing this work, they will ask to leave the bottom of the water. The surface security personnel will help them adjust the air volume, buoyancy can not be too large, the rising speed can not be too fast, otherwise it will cause safety accidents. If they complete the task, they can get a reward of 120000 yuan. If there is any problem in the process of diving into the water, the ground security personnel will immediately pull the safety rope and pull the person up. Therefore, two people need to cooperate with each other and trust each other. A netizen asked: The salvage price is so expensive, the salvage process is so dangerous, why not drain the water in the well? First of all, because the specific gravity of the mud is very large, between 1.3 and 1.4, if the mud is pumped out, the pressure of the hole wall will disappear, and the hole wall may collapse, so it is very difficult to fish out the drill bit. Moreover, some boreholes are tens of meters or hundreds of meters deep and have reached the underground water layer, where the water may not be pumped out in ten days and a half months. For the engineering side, time is money, but they can not afford it. Others say, why not use robots instead of human beings? In fact, as far as the current level of science and technology is concerned, there is no machine that can replace manual work to salvage drill bits underground. If it is operated by a machine, it will be more difficult to fish out the drill bit if it fails to fish out once and destroys the hole. Some netizens also suggested that a large magnet could be used to suck up the drill bit. It is true that some people have used this method, but it must have a strong enough electromagnet, and the weight of the drill bit will not be too heavy, the key drill bit must also be made of iron, if it is made of alloy, this method is not feasible. Although the work of water ghost is very dangerous, there are still people who are willing to work in such a high-risk industry because of its higher remuneration. So what kind of conditions do you need to engage in this industry? 1. First of all, we need to be young. Because they are young and strong, they can dive underwater for a longer time, because young people have better physical strength and can withstand greater external pressure than old water ghosts. The resistance of moving forward in the sticky mud is very great, and it also consumes a lot of physical strength. Only young people with good physical strength can go down and come up. Generally, the age of water ghost is before 30 years old, and after 30 years old, the physical strength is poor, so few people go down the well. After the age of 40, I can't do this job because I can't bear the strong pressure underground. 2. A strong water effort is required. Although they wear diving suits and masks, they also need good water work to work under complex holes. My uncle said that with the deepening of the depth underwater, the pressure is very high, the breathing sound is getting thicker and thicker, and there are all kinds of water grunts. 3. Professional training is required. They have to undergo professional training, understand all kinds of possible situations of drill bit falling, learn all kinds of coping methods, they must hold certificates and hang in qualified companies. 4. To have good psychological quality and professional skills, every time they receive a task, they must make a professional assessment of the underground situation. Of course, we need a few partners to cooperate with each other. If there is any accident in the person who sneaks into the borehole, the people on the ground should pull him up immediately. Conclusion: Some people think that the wages for salvaging drill bits are too expensive. If everything goes well, it will be 20,000 yuan an hour. They will think that the water ghost has made a lot of money. In fact, this profession is very dangerous. In addition, not every construction site will have the phenomenon of drill bit anchoring. Sometimes they only receive a job in ten days and a half months. Such dangerous work is not often available, and the fees are naturally higher. If twenty thousand yuan is salvaged every day, it will be six hundred thousand yuan a month. I think even if it is a dangerous job, there must be a lot of people competing to do it. In short, every line has its own rules. There are many dangerous jobs in today's society, such as installing air conditioners at high altitude and being a firefighter. Which job is not full of danger? No matter how dangerous it is, someone will do it because we really need money to live. We can't do it without money, don't you think? Return to Sohu to see more Responsible Editor: (function() { function getBrandHtml() { var brands = [],fastest dth hammer, html = ''; for(var i = 0; i < brands.length; i++) { var brand = brands[i]; if(brands.length i+1) { html+= ''+brand.name+''; } else { html+= ''+brand.name+'、'; } } return html; }; if(document.getElementById('linkBtn')){ document.getElementById('linkBtn').onclick = function() { $('#brands').removeClass('brand');$ ( '# tipInfo').text ( 'Real name responded'); $ ('#linkBtn').remove();$ ('.real-response .content').css('line-height', '20px');$ ('.real-response .time').css('line-height', '20px'); }; document.getElementById('brands').innerHTML = getBrandHtml(); }; })();。 wt-dthtools.com


13/09/2022
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Causes of sediment in rotary drilling pile and hole cleaning treatment! _ Mud

Original Title: Causes of Sediment of Rotary Drilling Pile and Hole Cleaning Treatment! Introduction Rotary drilling rig has high automation level and strong adaptability. However, due to the differences in mechanical property of different drilling rigs, personnel operation level and on-site technical management ability, especially the influence of site stratum conditions, and the industry has not yet compiled relevant construction technical specifications for rotary bored piles, and has not formed a systematic research on construction methods, a large number of quality problems of rotary bored piles in the construction process have also arisen. Thick sediment at the bottom of pile is one of the common quality problems. Excessive or too thick sediment at the bottom of the pile will have a serious impact on the quality of the pile foundation, which is mainly reflected in the following aspects: too thick sediment will seriously restrict the bearing capacity of the pile end and increase the settlement and displacement of the piles, which will cause huge hidden dangers to the overall structural safety of the superstructure. In view of the above problems, the current pile foundation code puts forward clear requirements for the thickness of sediment at the bottom of bored piles. In the Technical Code for Building Pile Foundations (JGJ94-2008), it is stipulated that the sediment thickness of end-bearing piles is ≤ 50mm, and the sediment thickness of friction piles is ≤ 100mm. Many local industry codes have also issued clear regulations to restrict this. However, in the actual construction, due to the lack of training for the operators of rotary drilling rig and the lax grasp of the construction process by the on-site technical management personnel, especially the influence of complex strata, the problem of excessive sediment at the bottom of piles is still serious. Therefore, how to prevent the generation of pile hole sediment in the construction process of rotary drilling pile, reasonably select the secondary hole cleaning process of pile hole, and ensure that the sediment at the bottom of the hole meets the design and specification requirements, has become an objective evaluation and application prospect of the rotary drilling rig in the industry. Based on the construction situation of rotary drilling cast-in-place pile in Shenzhen area, this paper analyzes the causes of sediment at the bottom of rotary drilling pile hole, puts forward several effective secondary hole cleaning methods, discusses the characteristics of different hole cleaning methods, and puts forward the comprehensive optimization selection method. 01 Cause Analysis and Control Measures of Sediment at the Bottom of Rotary Excavation Pile The sediment at the bottom of the rotary drilling cast-in-place pile may be produced in the drilling and hole forming, reinforcement cage placing, concrete pouring and other links of the rotary drilling rig construction. The analysis shows that the reasons for the sediment can be roughly divided into the following categories: 1.1 Collapse of pile hole wall 1.1.1 Cause analysis The filling layer of the pile hole orifice is unstable and collapses into the hole; the specific gravity of the mud is too low and the suspension capacity is poor; the drilling tool is lifted too fast, resulting in upward suction in the hole; the mud level in the hole drops when the drilling tool is lifted, and the mud in the hole is not replenished in time; the drilling tool scratches the hole wall when it is lifted and lowered; the reinforcement cage scratches the hole wall when it is lowered; concrete is not poured in time after the completion of the hole, and the. 1.1.2 Control measures: steel casing shall be placed at the orifice to protect the orifice, and the length of the casing shall be properly lengthened according to the formation conditions; the specific gravity of the mud shall be increased to improve the viscosity of the mud and reduce the sedimentation at the bottom of the hole; the footage of each round of rotary drilling shall be controlled, and it is strictly prohibited to lift the drill when the drilling cylinder is full, so as to avoid sucking the site; before the drilling tool raises the orifice, the mud in the hole shall be replenished in time to maintain the; When lifting and lowering the drilling tool, keep it centered and slowly lift and lower it to prevent scraping; lower the reinforcement cage to keep it centered and vertical; pour the pile body concrete in time after finishing the hole to reduce the auxiliary operation time. Expand the full text 1.2 Mud Sedimentation 1.2.1 Cause analysis The performance parameters of the mud are not qualified, and the wall protection effect is not good; the waiting time before pouring is too long, and the mud precipitates; the sand content of the mud is high. 1.2.2 Control measures Prepare the mud with appropriate parameters, and timely detect and adjust the mud performance; shorten the waiting time for pouring to avoid mud sedimentation; set up a mud sedimentation tank or a mud separator to separate the sediment in the mud and adjust the mud performance. 1.3 Drilling residues 1.3.1 Cause analysis The bottom of the drilling tool is deformed or worn too much, and the muck leaks to form sediment; the bottom of the drilling tool is limited by the structure itself, such as the height and spacing of the drill teeth, which cause too much muck to form sediment. 1.3.2 Control measures Appropriate drilling tools shall be selected, and the drilling bottom structure shall be checked frequently; the clearance between the rotary bottom and the fixed bottom shall be reduced; the diameter protection strip shall be repaired and welded in time, and the side teeth with serious wear shall be replaced; the arrangement angle and spacing of the drilling teeth shall be adjusted reasonably; the number of slag removal shall be increased to reduce the residue at the pile bottom. 1.4 Hole cleaning process 1.4.1 Cause analysis Hole collapse is caused by suction during hole cleaning; the mud performance is not up to standard during hole cleaning, and the sediment cannot be carried out of the hole bottom; the selection of hole cleaning process is unreasonable, and the sediment cannot be removed completely. 1.4.2 Control measures Control the suction force of the pump during hole cleaning to reduce the impact on the hole wall; change the slurry during hole cleaning and adjust the slurry performance index; select the appropriate secondary hole cleaning process according to the drilling conditions. Secondary hole cleaning technology of rotary drilling cast-in-place pilot Appropriate measures shall be taken to avoid sediment during rotary drilling construction. After the placement of reinforcement cage and pouring conduit, appropriate secondary hole cleaning process shall be selected for sediment treatment for pile holes with too thick sediment. Secondary hole cleaning is a key process to remove the sediment at the bottom of the hole by using the pouring conduit after the completion of rotary excavation, reinforcement cage and pouring conduit. The reasonable selection of secondary cleaning technology for pile hole is very important to remove the sediment at the bottom of the hole and ensure the quality of the pile body. At present, the secondary hole cleaning technology of rotary digging pile in the industry can be divided into the following three categories according to the mud circulation mode: mud positive circulation hole cleaning, reverse circulation hole cleaning and drilling tool without mud circulation hole cleaning. 02 Mud positive circulation hole cleaning 2.1.1 Process principle Mud positive circulation hole cleaning process is a commonly used hole cleaning method, in which the mud pumped by the mud pump is connected with the pouring conduit at the orifice through the rubber hose, and the mud is sent to the bottom of the hole; the mud sent to the bottom of the hole is suspended and carries the sediment at the bottom, and then returns to the ground through the annular space between the pouring conduit and the hole wall, flows into the circulation ditch and sedimentation tank, and then enters the mud tank for recycling. See Fig. 1 for the principle of positive circulation secondary hole cleaning process. Fig. 1 Schematic diagram of positive circulation secondary hole cleaning principle 2.1.2 Precautions for hole cleaning Attention shall be paid to the following items during the operation of mud positive circulation slag removal: (1) Select the appropriate mud pump. If the mud flow is too large, the hole wall will be scoured and the hole will collapse easily. If the mud flow is small, the sediment will rise slowly, the slag removal effect will be poor and the time will be long. In the actual construction, the flow and lift are taken as the basis for selecting the mud pump, and the 3PN mud pump with the power between 12 and 30 KW can be prepared according to the diameter of the pile hole. (2) Reduce the number of pipeline joints, avoid drastic changes in pipeline diameter and running direction, and reduce the on-way resistance and local resistance consumption in the mud circulation system. (3) In the process of mud circulation, the mud circulation system contains more coarse particles or rock debris, which will be brought into the hole repeatedly, affecting the hole cleaning effect. The waste residue in the sedimentation tank and mud tank shall be cleaned regularly. The mud circulation ditch can be enlarged or lengthened, and special personnel shall be assigned to dredge the slag in the ditch. (4) In the process of cleaning the hole, the guide pipe shall be lifted up and down and moved left and right according to the slag removal effect to speed up the disturbance of the sediment at the bottom of the hole, so as to achieve the effect of rapid slag removal. 2.2 Mud cyclone positive circulation hole cleaning 2.2.1 Process principle In order to reduce the large content of coarse particles in the mud in the secondary hole cleaning process of the positive circulation, improve the performance index of the mud, shorten the hole cleaning time and improve the hole cleaning effect, a mud cyclone is introduced to assist in hole cleaning in the mud positive circulation hole cleaning system, that is, a mud cyclone is connected in series on the ground on a rubber hose for pumping the mud into the bottom of the hole by a mud pump,dth button bits, and the coarse particles in the slurry are discharged before the slurry is pumped into the bottom of the hole. The effective separation of slurry and slag in advance ensures that high-quality slurry enters the bottom of the hole, reduces the repeated introduction of rock slag, effectively improves the slag-carrying capacity of the slurry, greatly shortens the hole cleaning time, improves the work efficiency and ensures the hole cleaning effect. See Fig. 2 for the plane layout of the secondary hole cleaning process of the mud cyclone. Fig. 2 Schematic diagram of secondary hole cleaning of cyclone 2.2.2 Precautions for hole cleaning Slurry cyclone positive circulation secondary hole cleaning relies on the cyclone device to effectively separate the slurry, which is easy to operate and has good separation effect. It is an upgraded process of ordinary slurry positive circulation hole cleaning system and a utility model patent technology owned by our company. At the same time, it has been appraised as the municipal construction method of Shenzhen engineering construction in 2011 and the provincial construction method of Guangdong engineering construction. It is practical and effective. And provides a new reliable choice for secondary hole cleaning. Attention shall be paid to the following during the secondary hole cleaning of the positive circulation of the mud cyclone: (1) Assign a special person to take charge of the working state of the cyclone and observe whether the slag outlet is blocked; if large foreign matters such as block stones, oyster shells and cement blocks are sucked into the inlet of the cyclone, the slurry inlet speed will be reduced, which shall be removed in time. (2) If the content of solid coarse particles in the slurry at the inlet of the cyclone is too high, or the valve at the underflow port is adjusted too small, the cyclone will be overloaded and the underflow port will be blocked. The bottom valve can be adjusted to keep the bottom slag discharge smooth. (3) Set special slag discharge tank at the slag outlet of the cyclone, and clean and discharge the slag in time. (4) The selection of cyclone shall be matched with the mud pump capacity. 2.3 Pump suction reverse circulation secondary hole cleaning 2.3.1 Process principle In order to ensure that the hole cleaning meets the design and specification requirements, the common practice for large and deep piles is to adopt the mud pump suction reverse circulation process. Pump suction reverse circulation secondary hole cleaning is to use the suction effect of the sand pump to create a negative pressure state in the inner cavity of the filling conduit. Under the action of atmospheric pressure, the mud in the annular space between the filling conduit and the hole wall flows to the bottom of the hole, is sucked into the inner cavity of the filling conduit, and then rises to the ground mud circulation system. After sedimentation treatment in the mud sedimentation tank, it flows into the hole from the mud tank and the mud circulation ditch. See Figure 3 for the working principle of pump suction reverse circulation secondary hole cleaning. Fig. 3 Schematic Diagram of Working Principle of Pump Suction Reverse Circulation Secondary Hole Cleaning 2.3.2 Precautions for hole cleaning Secondary hole cleaning by pump suction reverse circulation has the characteristics of strong suction capacity, short hole cleaning time and clean hole bottom, but attention shall be paid to the following during hole cleaning: (1) 6 BS reverse circulation sand pump is required to be added during hole cleaning. The pipeline layout of the overall circulation system is complex, the reverse circulation site operation is highly professional, and the formation of vacuum degree is difficult. (2) As the flow of the pump suction reverse circulation sand pump can reach 180m3/H, the suction capacity is super strong, and the negative pressure formed has a certain impact on the stability of the hole wall. For the pile hole with deep silt and thick sand layer, the reverse circulation flow shall be controlled. (3) When cleaning the hole,Tapered Rock Bit, pay attention to keep the water head height of the mud surface in the casing, and keep the balance between the amount of mud flowing back into the hole and the amount of suction. The consumption of pump suction reverse circulation mud is large, so it is necessary to control the performance and parameters of the mud and do a good job in the treatment of waste slurry and waste residue. 2.4 Air-lift reverse circulation treatment method 2.4.1 Process principle Air-lift reverse circulation hole cleaning is to insert a galvanized pipe with a length of about 2/3 hole depth into the conduit to send high-pressure air into the 2/3 hole depth of the conduit and mix it with the mud in the conduit. After inflation, a low-pressure area is generated in the conduit. The pressure difference between the inside and outside of the continuously inflated conduit increases continuously. When a certain pressure difference is reached, the balance is broken, and the mud is forced to spray back from the conduit under high pressure. At the same time, the rock slag at the bottom of the hole is carried by the high-speed mud and ejected back out of the orifice from the conduit. The principle of gas lift reverse circulation is shown in Figure 4 below. Fig. 4 Principle of gas lift reverse circulation 2.4.2 Precautions for hole cleaning The gas lift reverse circulation secondary hole cleaning process has the advantages of large pressure difference, fast flow rate and strong slag carrying capacity. During the operation of the slag removal process, in addition to reducing the resistance, moving the conduit, separating the mud and sand in the slurry, attention should also be paid to: (1) The configuration of air-lift reverse circulation equipment is relatively complex, so it must be debugged and optimized before the actual work, especially for the selection of air compressor, setting the appropriate length of air inlet pipe directly affects the efficiency of circulating slag removal. (2) Gas lift reverse circulation will cause negative pressure at the bottom of the pile hole, and hole collapse must be prevented when it is used in unstable strata. (3) In the process of reverse circulation operation, the water head height of the mud level in the casing shall be kept all the time, and the balance between the amount of mud flowing back into the hole and the amount of suction shall be kept consistent to prevent hole collapse. 2.5 "Submersible pump + mud purifier" secondary hole cleaning system 2.5.1 Process principle In order to solve the problems of poor secondary hole cleaning effect, complex mud circulation and large mud discharge of large-diameter and ultra-deep piles, our company has developed a "submersible pump + mud purifier" secondary hole cleaning system, that is, the submersible pump is connected with the perfusion conduit, when the submersible pump starts, it directly pumps the sediment at the bottom of the hole to form mud reverse circulation; The submersible electric pump is connected with the mud purification device with a rubber hose. The pumped mud enters the mud purification system to realize the separation of slurry and slag. The slag is directly discharged and loaded for transportation. The mud flows into the orifice through the outlet of the mud purifier again to maintain the height of the mud level in the hole, maintain the stability of the hole wall, and recycle to achieve the purpose of hole cleaning. See Fig. 5 and Fig. 6 for the working principle of the secondary hole cleaning system of "submersible pump + mud purifier". Fig. 5 Schematic Diagram of Secondary Hole Cleaning System of "Submersible Pump + Mud Purifier" Fig. 6 Site Layout of Secondary Hole Cleaning of "Submersible Pump + Mud Purifier" 2.5.2 Precautions for hole cleaning (1) The selection of mud purification device model shall be based on the submersible pump model, processing capacity, etc. When the submersible pump flow is not more than 100 m3/H, ZX-100 can be selected; When the flow of submersible electric pump is greater than or equal to 100 m3/H, ZX-200 can be selected to achieve the balance between flow and processing capacity and meet the requirements of mud purification capacity. (2) Orifice submersible electric pump is an important machine and equipment in the process of secondary hole cleaning. The submersible electric pump is respectively connected with the filling conduit and the mud purification device to form the mud reverse circulation secondary hole cleaning process. In order to ensure the sealing of the submersible pump, the submersible pump is generally sunk below the mud level to prevent air leakage. (3) After the hole cleaning system is installed, special inspection shall be carried out, including: the height of the filling conduit from the bottom of the hole, the tightness of each interface, the stability of the mud purification device, the safety of various electrical appliances, etc. The secondary hole cleaning shall be carried out if the inspection meets the requirements. (4) In the process of hole cleaning, closely monitor the height of the mud level at the orifice, and keep the amount of mud pumped and discharged by the submersible pump basically consistent with the amount of backflow mud, so as to ensure the water head height of the mud in the hole and keep the hole wall stable. 2.6 Hole cleaning with rotary drilling bucket (hole cleaning without mud circulation) 2.6.1 Process principle Rotary drilling bucket hole cleaning refers to a hole cleaning method in which a special slag fishing drilling bucket is used to remove the sediment in the hole. In the process of drilling and before pouring concrete, it is not necessary to use slurry positive circulation or reverse circulation to clean the hole. In this hole cleaning method, the rotary drilling bucket is mainly used to fish out the sediment at the bottom of the hole, and at the same time, the mud is used to protect the stability of the hole wall and suspend the sediment, so that the coarse particles or drilling slag in the mud in the hole are in a suspended state for a long time. After the installation of the reinforcement cage and the pouring conduit, there is little or no sediment at the bottom of the hole. 2.6.2 Practice of rotary drilling bucket for hole cleaning without mud circulation (1) Project overview: The pile foundation of Guoxin Financial Building in Futian Central District of Shenzhen has a diameter of φ1800, φ2000, φ2200 and φ2600mm, mining dth bit ,dth rock bit, a pile hole depth of 38 ~ 41mm, a pile bottom bearing stratum of 2m into moderately weathered granite or 0.5m into slightly weathered granite, and a compressive strength of 75 MPa for slightly weathered granite. (2) Pile foundation construction and hole cleaning measures: Sany Heavy Industry SR420II rotary drilling rig is selected for pile foundation construction, 3m pile casing is buried at the orifice, and chemical slurry is prepared from sodium hydroxide powder, sodium hydroxide and CMC. Taking the hole with a pile diameter of 2,600 mm as an example, the upper fill, silty clay, residual soil and strongly weathered rock stratum (about 38 m deep) shall be drilled in two stages according to the diameter of 2,200 mm and 2,600 mm by the rotary drilling bucket. Since the rotary drilling is carried out with static mud without circulation, the drilling speed is fast (about 6 hours), and the mud wave on the hole wall is thin, At this stage, the mud shall be controlled at a specific gravity of 1.08 ~ 1.20 and a viscosity of 18 ~ 20 S. The lower moderately weathered and slightly weathered rock strata are hard and deeply penetrated into the rock. The rotary drilling of hard rock adopts stepped reaming, that is, the cutter drill barrel with a diameter of φ 800 mm is used to drill to the designed final hole depth, and the rock core is directly taken out; After the final hole depth is determined, the rotary drilling bucket or drill barrel with diameters of φ1300mm, φ1500mm, φ1800mm, φ2000mm, φ 2200mm, φ 2400mm and φ2600mm shall be used to ream the hole from top to bottom. After the drilling of each stage of hole is completed, the dredger bucket shall be used to clean the hole. The rock strata are reamed and dredged by stages, so that the construction time of drilling hard rocks in each stage of hole is shortened, the resistance of hard rock drilling is reduced, and the rock drilling efficiency is improved. In order to reduce the heat energy of the friction between the drill bit pick and the hard rock, the mud is controlled to have a low specific gravity and medium viscosity during drilling in the rock formation, with a specific gravity of 1.05 ~ 1.15 and a viscosity of 18 ~ 22 S. After finishing the hole and before placing the reinforcement cage and pouring the guide pipe, use sodium hydroxide to adjust the performance of the mud at the bottom of the hole, so that the mud with small specific gravity (specific gravity 1.05 ~ 1.10) and large viscosity (viscosity 22 ~ 25s) can be formed within about 10 m above the bottom of the hole, so that the mud at the bottom is in a flocculent state and the coarse particles in the mud are in a suspended state. Ensure that the sediment at the bottom of the hole meets the design requirements after the reinforcement cage and pouring conduit are placed. (3) Rotary drilling and pile-forming effect: for the rotary drilling pile of Guoxin Mansion, the pile with a diameter of 2,600 mm, a depth of 41 m, and a depth of 3 m into the moderately (slightly) weathered granite shall be cleaned without slurry circulation, and the pile formation shall be completed every 2.0 ~ 2.5 days; for the piles with a diameter of 2,000mm and below, 2 ~ 3 piles can be completed every day. 2.6.3 Precautions for rotary drilling bucket without mud circulation slag removal (1) Protect the orifice and hole wall. When the rotary drilling bucket is used to remove the slag, the pile casing at the orifice shall be fully buried, and the water head height of the mud level in the pile casing shall be maintained to prevent the collapse of the orifice and the collapse of the hole wall during drilling. Due to the large pile diameter, the mud level in the pile casing will drop by about 1.2m before the rotary drilling bucket is lifted from the orifice. At this time, it is necessary to supplement the mud in time to maintain the liquid level in the pile casing. (2) The structure of the dredge bucket is reasonable. After drilling to the depth of the designed bearing stratum of the pile hole, use the pick bailing bucket to idle for several circles without pressurization, so as to make the pile bottom as flat as possible and facilitate slag removal; when drilling in the rock stratum, the slag removal guide plate should be as short as possible or flat-bottomed as possible, so that the slag soil at the bottom of the hole can enter the cylinder; the smaller the height of the slag removal guide plate is, the better the effect of slag removal is. The bottom structure of the slag removal drilling bucket must be modified according to the shape of the pick bucket bottom to minimize the height of the guide plate and the center cone. (3) Mud management is the key. The rotary drilling rig shall be equipped with a special mud team, and a special person shall be assigned to be responsible for the modulation and management of mud. (4) The control of mud performance is the key in the slag cleaning process of the rotary drilling bucket. In order to realize the hole cleaning without mud circulation, it is necessary to scientifically and reasonably control the allocation of mud and dynamically use the mud. For example, if the drilling time of the upper soil layer is short, the specific gravity of the mud should be increased appropriately to maintain the stability of the hole wall; if the drilling resistance of the rock stratum is large and the drilling time is relatively long, the specific gravity of the mud can be reduced appropriately; After the rotary drilling bucket is dredged after the hole is finished, due to the need to place the reinforcement cage and pour the conduit, the mud is prepared into low specific gravity and high viscosity at this time, so that the mud at the bottom section forms flocculent and consistency, which improves the suspension capacity of the mud and prevents the solid particles in the mud from sinking to the bottom of the hole. (5) After the drilling tool is cleaned, the auxiliary operation time shall be shortened, and the concrete of the pile body shall be poured into the cage immediately to minimize the amount of sediment at the bottom of the hole. 03 Comparison and analysis of secondary hole cleaning technology for rotary drilling pile bottom sediment The characteristics of the slag removal method are compared and analyzed from four aspects of application scope, equipment configuration, slag removal efficiency and mud consumption: 3.1 Scope of application (1) Normal circulation slag removal: including cyclone normal circulation slag removal, which is suitable for pile holes with small diameter and depth, and is convenient for mud to carry sediment back upward. Generally, the pile diameter is 1.5m and below, and the depth is within 40m. Otherwise, it is necessary to configure a super-power mud circulating pump for implementation. (2) Reverse circulation slag removal: including pump suction reverse circulation, submersible pump + mud purifier reverse circulation hole cleaning, and air-lift reverse circulation slag removal. It is applicable to large-diameter piles with a pile diameter of more than 1.5m. In order to provide sufficient pressure difference for circulation, it is generally required that the pile hole depth is more than 10m, the pump suction reverse circulation pile depth can reach about 80m, and the air-lift reverse circulation hole depth can exceed 100m. (3) Slag removal of drilling tools adopts slag-fishing drilling tools and mud hole cleaning, which is suitable for all rotary drilling processes, especially for long casing, full casing drilling and mud circulation which is easy to cause hole collapse. To sum up, the application range of positive circulation slag removal is small, the application range of reverse circulation slag removal is large, and the application range for drilling tool slag removal is the widest. 3.2 Equipment configuration (1) Positive circulation slag removal: the required equipment includes mud pump, conduit, etc.; (2) Cyclone positive circulation slag removal: the required equipment includes mud cyclone, mud pump, conduit, etc.; (3) Pump suction reverse circulation slag removal: the required equipment is sand and gravel pump and conduit; (4) Equipment required for gas lift reverse circulation slag removal: air compressor, mud pump, conduit, air inlet pipe, joint, etc.; (5) Submersible electric pump + mud purifier reverse circulation hole cleaning: Dth electric pump, mud purifier, conduit, etc.; (6) Drilling tool slag removal: configure the slag removal drill bit suitable for the pile diameter. In the above six slag removal methods, the reverse circulation system requires the most equipment, the system structure is more complex, and the operation has certain technical difficulties, such as the control of reverse circulation vacuum degree. In addition, the drilling tool does not need too much external equipment for slag removal, but because the price of the rotary drilling bucket for slag removal is close to that of the ordinary rotary drilling tool, the price of the large-diameter drilling tool for slag removal is more expensive, and different diameters of drilling buckets are needed when the diameters are different, the initial investment is more, which is a disadvantage compared with the mud circulation slag removal. 3.3 Slag removal efficiency Among the above positive circulation, reverse circulation and drilling tool slag-cleaning methods without mud circulation, the drilling tool has the highest slag-cleaning efficiency, which can meet the injection requirements after 3 to 5 times of lifting and discharging; the gas lift or pump suction reverse circulation takes the second place, which takes 2 to 4 hours to clean the slag, while the positive circulation has the lowest efficiency, which takes 4 to 6 hours. However, the actual slag removal time is closely related to equipment configuration, engineering geological characteristics, mud quality and other factors, so it is difficult to generalize. 3.4 Mud consumption Among the above six hole cleaning processes, the reverse circulation mud consumption is the largest, the positive circulation is the second, and the drilling tool slag cleaning is the smallest. 04 Optimization and selection of slag removal technology for rotary drilling pile The key to ensure the quality of pile hole is to optimize the selection of rotary drilling pile slag removal and secondary hole cleaning process. We believe that the following points should be grasped: (1) There are many methods for slag removal of rotary drilling piles. We advocate that there is no best method, only suitable method. Each process method must be suitable for equipment, personnel, stratum and environment. If it can be handled simply, it will not be complicated to operate, so as to achieve the purpose of hole cleaning. (2) For small-diameter piles and shallow piles, due to small pile hole section and small hole cleaning depth, the secondary hole cleaning with positive circulation of mud can better meet the requirements. (3) For large-diameter piles and ultra-deep piles, it is slow and ineffective to use slurry positive circulation for hole cleaning. At this time, it is necessary to use slurry reverse circulation for hole cleaning. In the reverse circulation hole cleaning process, the pump suction or gas lift circulation process is reasonably selected according to the hole diameter and depth. (4) In the process of secondary hole cleaning, the use of mud purification device (such as cyclone, black cyclone series) can quickly separate the solid coarse particles in the mud, reduce the sand content of mud, improve the performance of mud, accelerate the separation of slurry and slag, improve the speed of hole cleaning, ensure the quality of hole cleaning and reduce the amount of mud discharge, which can get twice the result with half the effort. (5) The drilling tool has no slurry to clean the slag circularly, which is a new method of hole cleaning worth advocating in the construction of rotary drilling pile. Its biggest characteristic is that after the reinforcement cage is placed in the drilling hole and the conduit is poured, the bottom of the hole can be kept less or no sediment, and there is no need for secondary hole cleaning. It has good slag cleaning effect and less auxiliary equipment, which greatly improves the efficiency of pile formation. The high efficiency of the rotary excavator is brought into full play. This slag removal technology has been used in a number of rotary pile foundation construction sites such as Guoxin Financial Building, Alibaba Building, Aliyun Building and Life Building, and has achieved satisfactory results, which should be vigorously promoted. (6) There are a large number of rotary pile construction teams in Shenzhen, and the number of individuals is large. The performance, management level and operation ability of pile drivers are quite different. They are often hastily started, lack of training, and lack of mastery of rotary pile construction technology and operation skills, especially the mastery of drilling mud performance. It is often difficult to achieve the desired results. Therefore, in the specific operation of secondary hole cleaning, the hole cleaning process should be adjusted according to the actual situation. In particular,mining dth bit, if the drilling tool without mud circulation cleaning process is adopted, its practical application has a high technical content. If the sediment at the bottom of the hole cannot meet the design requirements after placing the reinforcement cage and pouring the guide pipe and before pouring the concrete, the mud positive circulation or reverse circulation must be used for secondary hole cleaning. Return to Sohu to see more Responsible Editor:. wt-dthtools.com


13/09/2022
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The legend of the chemical equipment is here. Can you tell its name at a glance? _ Code

Original title: The legend of chemical equipment is here. Can you tell its name at a glance? All kinds of chemical equipment are the most common and essential in chemical plants, and each kind of chemical equipment has its unique shape on the drawing, so can you say its name at a glance? Today, Xiao Qi has sorted out more than 100 high-definition big pictures, so that you can know the name of the equipment on the drawings at a glance. There are many kinds of chemical equipment, and there are many ways to classify them. For example, according to the structure and material, they can be divided into carbon steel equipment, stainless steel equipment and non-metallic equipment. According to the pressure, it can be divided into high pressure equipment, medium pressure equipment, vacuum equipment and normal pressure equipment. It is roughly divided as follows according to the use function: Chemical containers: tanks, pots, kettles, jacketed glass reactor ,jacketed glass reactor, etc; Separator: packed tower, float valve tower, bubble cap tower, rotating disc tower, etc; The reactor comprises a tubular reactor, a fluidized reactor and a stirred tank reactor; Heat exchanger: tubular, plate heat exchanger, coil heat exchanger, etc; Heating furnace: electric heating furnace, tubular cracking furnace, waste heat boiler, etc.; Crystallization equipment: solution crystallizer, melting crystallizer, etc.; Other special chemical equipment, etc. Tower equipment (code T) Packed tower Plate column Expand the full text Spray Tower Tower internals Downcomer Liquid receiving tray Valve tray Bubble cap column tray Grating plate Riser Turbulent ball tower Sieve tray Distributor (Distributor) Sprinkler Screen defoaming layer Filler demister layer Reactor (code R) Fixed bed reactor Tubular reactor Fluidized bed reactor Reaction kettle (closed type with stirring jacket) Reaction kettle (open type with stirring jacket) Reactor (open inner coil with stirring jacket) Industrial furnace (code F) Box-type furnace Cylindrical furnace Flare stack (code S) Chimney Torch Heat exchanger (code E) Schematic diagram of heat exchanger Fixed tubesheet heat exchanger U-tube heat exchanger Floating head tubular heat exchanger Double Tube Heat Exchanger Kettle type heat exchanger Plate heat exchanger Spiral plate heat exchanger Finned tube heat exchanger Coil (coil) heat exchanger Spray Cooler Scraper film evaporator Tubular (thin film) evaporator Induced draft air cooler Air supply type air cooler Fin tube heat exchanger with fan Pump (code P) Centrifugal pump Water ring vacuum pump Rotary pump and gear pump Screw pump Diaphragm pump Submerged pump Jet Pump Vortex pump Compressor (code C) Air Blower Rotary compressor (vertical) Centrifugal compressor Reciprocating compressor Two-stage reciprocating compressor Four-stage reciprocating compressor Vessel (Code V) Conical roof tank (Underground, semi-underground) pool, trough,hemp extraction centrifuge, pit Floating roof tank Vessel with dome and conical bottom Butterfly head vessel Flat top container Dry gas holder Wet gas holder Spherical tank Horizontal vessel Packing defoaming separator Wire mesh defoaming separator Cyclone separator Dry electrostatic precipitator Wet electrostatic precipitator Fixed bed filter Filter with filter cartridge Equipment internals accessories Vortex breaker Insert a tubular vortex breaker Impingement plate Heating or cooling component Agitator Hoisting and transportation machinery (code L) Chain block (with trolley) Electric Hoist Single beam crane (manual) Single beam crane (electric) Slewing crane jib crane Hook bridge crane Belt Conveyor Scraper conveyor Bucket Elevator Trolley Weighing machine (code W) Belt dosing scale Ground scale Other machinery (code M) Filter press Rotary drum (rotary disc) filter Perforated shell centrifuge Non-porous shell centrifuge Screw filter press Extruder Kneading machine Mixer Power machine Motor Internal combustion engine, gas engine Steam Turbine Other power machines Centrifugal expander, turbine Piston expander -END-Return to Sohu to see more Responsible Editor:. toptiontech.com


13/09/2022
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