Construction method of deep rotary digging hole-forming cast-in-place pile

Abstract

The invention relates to the technical field of building engineering construction, in particular to a deep rotary digging hole-forming cast-in-place pile construction method, which innovates on the basis of a traditional construction method, realizes real-time monitoring, data analysis and decision support of a construction process by establishing a rotary digging hole-forming cast-in-place pile construction informatization management platform, and simulates and optimizes the construction process by utilizing a BIM technology. The construction efficiency and quality are improved, intelligent equipment is introduced to assist constructors in field operation and monitoring, artificial intelligence and big data technologies are adopted to predict and early warn quality problems in the construction process, a novel power system is adopted, energy consumption and emission are reduced, a drilling control system is adopted, and the drilling precision and perpendicularity are ensured. The conditions in the drilling process are monitored in real time through the data monitoring and sensor technology, drilling parameters are conveniently adjusted in time, the circulating speed and the utilization rate of slurry are increased by adopting an efficient slurry pump and a larger-capacity slurry pool, and accurate installation of a reinforcement cage is ensured by adopting auxiliary tools such as a guiding device and a positioner.

Description

Technical Field

[0001] The invention relates to a deep rotary drilling bored pile construction method, in particular to a deep rotary drilling bored pile construction method, belonging to the technical field of building engineering construction. Background Art

[0002] Construction engineering is a broad concept involving many aspects: construction engineering refers to engineering facilities built with building materials for all production, life and environmental governance. In a narrow sense, it mainly refers to various houses and their affiliated structures, such as apartments, villas, schools, hospitals, etc., and also includes buildings such as roads and railways. Construction engineering mainly includes the following types of projects: housing engineering: industrial construction engineering; transportation construction engineering; water conservancy construction engineering, etc.; among them, deep rotary drilling and bored pile construction is an important part of the construction process of construction engineering. Deep rotary drilling and bored pile is a rotary drilling bit carried by a rotary drilling rig to drill the ground soil layer by layer to form a hole of a certain depth. Subsequently, a steel cage is suspended in the hole and concrete is poured to finally form a solid reinforced concrete pile body to improve the stability and bearing capacity of the foundation. However, the existing deep rotary drilling and bored pile construction method still has the following problems during construction: 1. Insufficient technical innovation; 2. Lack of environmental protection innovation, waste of a lot of resources; 3. Insufficient construction management.

[0003] Therefore, it is urgent to improve the deep rotary bored pile construction method to solve the above-mentioned problems. Summary of the invention

[0004] In order to achieve the above object, the main technical scheme adopted by the present invention includes: a deep rotary bored cast-in-place pile construction method, comprising the following steps:

[0005] S1: Construction preparation: 1. Measurement and positioning: Carry out unit project positioning measurement according to the control point coordinates provided by the construction unit, and then use lime to lay out the concrete guide wall edge according to the design drawings;

[0006] 2. Guide wall construction: Concrete or reinforced concrete guide wall is constructed on the top of the pile. The guide wall is 1.2m wide on each side, 25cm thick, 1220cm in diameter, with a strength grade of C20 concrete. The steel bars are arranged strictly according to the design requirements.

[0007] 3. Construction management preparation: Establish an information management platform for rotary bored pile construction to provide real-time monitoring, data analysis and decision support for the construction process; use BIM technology to simulate and optimize the construction process; introduce robots, drones and other intelligent equipment to assist construction personnel in on-site operations and monitoring; use artificial intelligence and big data technology to predict and warn of quality problems during the construction process;

[0008] S2: Casing burial: Casing shall be set according to the pile position. The inner diameter of the casing shall be 100mm larger than the drill bit diameter. The casing position shall be correctly and stably buried. The deviation between the center of the casing and the center of the pile position shall not be greater than 50mm. The deviation of the inclination shall not be greater than 1%. Clay shall be used to fill the space between the casing and the pit wall. The casing shall be buried by the static pressure method of the rotary drilling rig.

[0009] S3: Drilling and testing: 1. Drilling rig in place: After the casing is buried, check the working status of the rotary drilling rig. If it is in good condition, move the rotary drilling rig to the front of the bored pile to be constructed. Use the automatic adjustment control system of the drilling rig to level the drilling rig, adjust the verticality of the drill rod, align it with the pile position, and start the drilling machine for drilling construction; when drilling, introduce advanced drilling control system to monitor the soil layer changes and hole wall stability in real time during the drilling process, and use more efficient mud pumps and larger capacity mud pools when drilling; the new power system drives the drilling machine to operate;

[0010] 2. Hole detection: During the drilling process of the rotary drilling rig, the drilling depth is measured regularly. When it approaches the designed depth, the drilling speed is slowed down and the drilling is stopped after reaching the designed depth. The steel bar detection cage and measuring rope are lowered to check the hole diameter and hole depth;

[0011] S4: Initial hole cleaning: After drilling to the designed hole depth and conducting hole testing, lower the drill bucket to the bottom of the hole and rotate it mechanically for several circles to put as much loose soil as possible into the bucket. After pulling out the drill, the loose soil at the bottom of the hole still needs to be cleaned;

[0012] S5: Steel Cage Installation: 1. Steel Cage Production: After the steel bars arrive at the site, the steel bar team cuts the steel bars according to the design drawings and under the guidance of the on-site construction personnel, and then produces the steel cage. The steel cage is produced using automated and modular steel cage production technology;

[0013] 2. Lifting of steel cage: After the bored pile is bored and the first hole cleaning is completed, the steel cage made according to the design requirements and accepted shall be placed in the hole. When lowering, the steel cage shall be kept straight and it is strictly forbidden to swing and collide with the hole wall. After it is in place, the positioning steel bars shall be welded. Auxiliary tools such as guide devices and positioners shall be used during the lifting and installation.

[0014] S6: Lowering the guide tube: After the steel cage is lowered to the designed depth, immediately lower the concrete conveying guide tube, completely lower the guide tube to the bottom of the hole, and after checking that it is correct, gently lift the guide tube, control the bottom opening to be 0.25 to 0.4m away from the bottom of the hole and located in the center of the borehole;

[0015] S7: Secondary hole cleaning: After the steel cage and conduit are installed, the hole depth is measured again. If the thickness of the sediment in the hole does not meet the design requirements, secondary hole cleaning is required. Add clean water to the hole to circulate the mud, and install a mud separator until the mud in the hole meets the design requirements;

[0016] S8: Pouring underwater concrete:

[0017] S8.1: After the hole is cleaned to the required level, the concrete pouring conduit should be lowered to carry out the concrete pouring work;

[0018] S8.2: Before pouring concrete, the concrete conduit must be firmly installed, the sealing ring must be properly placed, and the bottom of the conduit must be 0.3-0.5m away from the bottom of the hole;

[0019] S8.3: The initial pouring volume of concrete shall ensure that the bottom of the conduit is buried 1.0m below the concrete surface during the initial pouring;

[0020] S8.4: The buried depth of the conduit should be 2-6m. Measure the buried depth of the conduit and the height difference of the concrete surface inside and outside the conduit, and fill in the underwater concrete pouring record;

[0021] S8.5: Concrete shall be poured continuously. The pouring time of each pile shall be controlled according to the initial setting time of the initial batch of concrete. All failures during the pouring process shall be recorded and filed;

[0022] S8.6: Control the amount of the last pouring, so that the pile top is not too low, and the height of the grout removed is such that the exposed pile top concrete reaches the design strength value;

[0023] S9: Pull out the casing and move the machine: After the concrete pouring is completed, remove the casing and move the rotary drilling rig to the next cast-in-place pile for construction;

[0024] S10: Chiseling pile head: After the pile is formed and the strength reaches the requirement, the earth and stone around the pile are excavated to reach the bottom elevation of the cap, and the pile head is processed manually to reach the designed pile top elevation and meet the design strength requirements;

[0025] S11: Pile foundation quality inspection: Ultrasonic testing is used to inspect the pile body quality of interlocking piles. The number of piles to be inspected is 20% of the total number and shall not be less than 5. When the pile body integrity category determined by ultrasound is Class III or Class IV, the core drilling method should be used for additional inspection. The number of piles to be inspected is 1% of the total number of piles, 1 hole is drilled for each pile, and shall not be less than 3 piles.

[0026] Preferably, the guide wall construction process in S1 is as follows:

[0027] S1.1: Leveling the site: clearing the surface debris and filling and rolling the trenches for the migration of ground pipelines;

[0028] S1.2: Measure and lay out the pile positions: Calculate the coordinates of the center line of the pile row according to the coordinates provided in the design drawings, use the total station to carry out field layout according to the ground wire control points, and make pile guards as the control center line for the guide wall construction;

[0029] S1.3: Excavation of guide wall trench: After the stake position layout line meets the requirements, the trench can be excavated. Mechanical excavation is adopted, and manual construction is coordinated. The excavation depth is 15cm below the ground surface, so that the top of the guide wall is higher than the original ground. After the excavation is completed, the center line is immediately introduced under the trench to control the bottom formwork and template construction;

[0030] S1.4: Formwork construction: The formwork adopts self-made integral steel formwork, the template diameter of the reserved positioning hole of the guide wall is 1220cm, and the diameter of the pipe sleeve is enlarged by 2cm. The formwork reinforcement adopts 5×10 square wood support, and the support spacing is not more than 1 meter;

[0031] S1.5: Concrete construction: The guide wall is made of commercial concrete, which is manually poured into the mold. The concrete is poured symmetrically and alternately on both sides. The vibrator is an inserted B50 vibrator with a vibration interval of about 600mm. The mold is removed after the concrete strength reaches 70%. After the mold is removed, the opposite support is immediately added to ensure that the guide wall remains stable during construction. The deviation between the center of the reserved hole in the guide wall and the center of the pile position is not more than 20mm.

[0032] Preferably, the construction sequence of drilling holes in S3 is as follows: the supporting pile structure adopts interlocking piles, the piles are arranged in a manner of alternating arrangement of a reinforced concrete B pile and a plain concrete A pile, the piles are divided into two types of piles, A and B, according to the order of construction, the unreinforced A piles are constructed first, and the B piles need to be reinforced, and when the B piles are constructed, the concrete of the intersecting parts of the adjacent A piles is cut off for interlocking, and the strength of the A piles is required to reach 85% or more before the B piles can be constructed.

[0033] Preferably, the construction process of drilling holes in S3 includes:

[0034] S3.1: Preparation of slurry materials: Bentonite is used as the slurry material. Before use, bentonite is sampled, subjected to mud ratio test and physical analysis. Qualified bentonite is put into a mud mixer and fully stirred for 6-8 minutes, and then placed in a pool for more than 24 hours to fully hydrate it before delivery. According to the soil conditions on site, part of the mud is formed during the pile formation process. During the trough cleaning process, the mud is precipitated in the sedimentation tank and a part of high-quality mud is reserved. After underwater concrete pouring, a part of the mud is replaced by concrete and then precipitated or chemically treated, and a part of the mud that meets the requirements is retained.

[0035] S3.2: Mud circulation system: The mud circulation system includes: a large mud pool, a mud sedimentation pool, a mud separator, a mud pump, and a high-pressure submersible pump. During the drilling process: the mud in the mud pool is directly pumped into the pile in the hole by a mud pump. After the hole is completed, the mud in the hole is pumped to the mud separator, and the slag slurry is separated by the mud separator. The mud is stored in the mud pool for use in the construction of the next pile hole section. The mud circulation during the cleaning process is pumped by the high-pressure submersible pump to the sand separator for sand separation. After the mud is qualified, it flows back to the hole. For the mud circulation of underwater concrete pouring, two mud pumps are placed near the concrete pouring hole to pump the mud to the mud pool and the slurry storage tank during concrete pouring.

[0036] S3.3: Drilling construction: 1. Align the drill bit, lower the drill bit, touch the ground, rotate, and excavate. Use the drill bit's own weight or the pressurized oil cylinder as the drilling pressure; 2. When the drill bit is filled with debris, lift it up. While paying attention to the changes in the groundwater level, add mud into the hole, and always keep the water level in the pile hole about 1m away from the top of the pile hole; 3. Lift and open the drill bit bottom plate, dump the soil in the drill bit to one side of the hole, and transport it away after the hole is completed; 4. Close the valve of the drill bit bottom plate, turn the drill bit back to the drilling site, align it with the hole position, and then lower it into the hole to continue drilling; 5. When the drilling depth is close to the designed hole bottom elevation, add water in time to adjust various indicators such as mud density, and clean the hole while drilling.

[0037] Preferably, the initial hole cleaning in S4 uses a sediment treatment drill bucket to discharge sediment. After the hole cleaning is completed, the sediment thickness at the bottom of the hole meets the following requirements: the sediment thickness of the bite pile is less than 200 mm, and the sediment thickness of the engineering pile is ≤50 mm.

[0038] Preferably, a special spiral threaded conduit is used for lowering the S6 middle conduit, the conduit adopts a 300mm inner diameter conduit, the middle section is 2.6m long, the lowest section is 4-5m long, and it is equipped with 0.5m, 1m, and 1.5m non-standard sections. The axis difference after the conduit is assembled does not exceed 0.5% of the borehole depth and is not greater than 10cm. The test pressure is 1.5 times the hydrostatic pressure at the bottom of the hole.

[0039] Preferably, the actual effective pile length after pile formation in S7 is not less than the designed effective pile length, the sediment thickness in the hole is <200mm for bite piles and ≤50mm for engineering piles, the mud density within 500mm from the bottom of the hole should be less than 1.25, the sand content ≤8%, and the viscosity ≤28.

[0040] Preferably, the concrete pouring in S8 adopts C45 and C20 underwater commercial concrete, the slump of concrete is 180-200mm, the filling coefficient of concrete pouring is ≥1.0, and the slump should be controlled at 18-22cm.

[0041] Preferably, when pouring the first batch of concrete in S8, the distance from the lower end of the conduit to the bottom of the hole is 0.25-0.4m, the first batch of concrete reserves in the storage hopper ensures that the depth of the conduit buried in the concrete after pouring is not less than 1.0m, and the initial setting time of the concrete should be greater than the entire pile pouring time.

[0042] Preferably, the drilling control system in the S3 includes automatic positioning and automatic deviation correction systems to ensure the accuracy and verticality of the drilling, and the new power system in the S3 adopts electric power, hybrid power, etc.

[0043] The present invention has at least the following beneficial effects:

[0044] 1. By innovating the traditional deep-drilling bored pile construction method, establishing an information management platform for the construction of rotary bored piles, achieving real-time monitoring, data analysis and decision support of the construction process, using BIM technology to simulate and optimize the construction process, improving construction efficiency and quality, introducing robots, drones and other intelligent equipment to assist construction personnel in on-site operations and monitoring, using artificial intelligence and big data technology to predict and warn of quality problems in the construction process, solving the problem of insufficient construction management; using new power systems such as electric and hybrid power to reduce energy consumption and emissions, solving the problem of insufficient environmental innovation, introducing advanced drilling control systems to ensure the accuracy and verticality of drilling holes, using data monitoring and sensor technology to monitor soil layer changes and hole wall stability in real time during the drilling process, so as to adjust drilling parameters in time, and improving the mud circulation system, such as using more efficient mud pumps and larger-capacity mud pools to increase the circulation speed and utilization rate of mud, using guide devices, positioners and other auxiliary tools to ensure the accurate installation of steel cages, thus solving the problem of lack of technological innovation. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0046] Figure 1 It is a schematic diagram of the process of the present invention;

[0047] Figure 2 It is a schematic diagram of the construction process of drilling rig hole forming of the present invention;

[0048] Figure 3 It is a guide wall construction flow chart of the present invention;

[0049] Figure 4 It is a construction sequence diagram of the occlusal pile of the present invention;

[0050] Figure 5 It is a schematic diagram of the steel bar construction of the present invention;

[0051] Figure 6 It is a schematic diagram of the bentonite slurry ratio of the present invention. DETAILED DESCRIPTION

[0052] The following will describe the implementation methods of the present application in detail with the help of accompanying drawings and examples, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0053] like Figure 1-Figure 6 As shown, the deep rotary bored pile construction method provided in this embodiment includes the following steps:

[0054] S1: Construction preparation: 1. Measurement and positioning: Carry out unit project positioning measurement according to the control point coordinates provided by the construction unit, and then use lime to lay out the concrete guide wall edge according to the design drawings;

[0055] 2. Guide wall construction: Concrete or reinforced concrete guide wall is constructed on the top of the pile. The guide wall is 1.2m wide on each side, 25cm thick, 1220cm in diameter, with strength grade C20 concrete. The steel bars are arranged strictly according to the design requirements.

[0056] The guide wall construction process is as follows:

[0057] S1.1: Leveling the site: clearing the surface debris and filling and rolling the trenches for the migration of ground pipelines;

[0058] S1.2: Measure and lay out the pile positions: Calculate the coordinates of the center line of the pile row according to the coordinates provided in the design drawings, use the total station to carry out field layout according to the ground wire control points, and make pile guards as the control center line for the guide wall construction;

[0059] S1.3: Excavation of guide wall trench: After the stake position setting line meets the requirements, the trench can be excavated. Mechanical excavation is adopted, and manual construction is coordinated. The excavation depth is 15cm below the ground surface, so that the top of the guide wall is higher than the original ground. After the excavation is completed, the center line is immediately introduced into the trench to control the bottom formwork and template construction to ensure the correctness of the center line of the guide wall;

[0060] S1.4: Formwork construction: The formwork adopts self-made integral steel formwork, the template diameter of the reserved positioning hole in the guide wall is 1220cm, and the diameter of the pipe sleeve is enlarged by 2cm. The formwork reinforcement adopts 5×10 square wood support, and the support spacing is not more than 1 meter; ensure that the reinforcement is firm, strictly prevent the formwork from running, and ensure the accuracy of the axis and clearance;

[0061] S1.5: Concrete construction: The guide wall is made of commercial concrete, which is manually placed in the mold. When pouring concrete, the two sides are symmetrical and alternate. If the mold is shifted, the pouring of concrete should be stopped immediately, the template should be reinforced again, and the pouring can be continued after it is corrected to the designed position. The vibrator is inserted with a B50 vibrator, and the vibration interval is about 600mm to prevent uneven vibration and prevent the phenomenon of shifting due to excessive vibration in one place. The mold is removed after the concrete strength reaches 70%. After the mold is removed, the opposite support is immediately added to ensure that the guide wall remains stable during construction. The deviation between the center of the reserved hole of the guide wall and the center of the pile position is not more than 20mm;

[0062] 3. Construction management preparation: Establish an information management platform for rotary bored pile construction to monitor the construction process in real time, analyze data and provide decision support. Use BIM technology to simulate and optimize the construction process to improve construction efficiency and quality. Introduce robots, drones and other intelligent equipment to assist construction personnel in on-site operations and monitoring. Use artificial intelligence and big data technology to predict and warn of quality problems in the construction process and take preventive measures in advance.

[0063] S2: Casing burial: Casing shall be set according to the pile position. The inner diameter of the casing shall be 100mm larger than the drill bit diameter. The casing position shall be buried correctly and stably. The deviation between the center of the casing and the center of the pile position shall not be greater than 50mm, and the deviation of the inclination shall not be greater than 1%. Clay shall be used to fill the space between the casing and the pit wall. The casing shall be buried by the static pressure method of the rotary drilling rig. When burying, firstly, the drilling rig shall be correctly positioned so that the verticality of the machine body, the verticality of the drill rod and the three lines of the pile position steel bar are aligned. Then, the barrel drill bit shall be placed on the top of the drill rod, and then the casing shall be lifted by a crane and correctly positioned. The casing shall be pressed vertically into the soil with the rotary drilling rod. After the casing is buried, the center of the pile position shall be led back through four control guard piles so that the center of the casing coincides with the center of the pile position, and the position of the guard pile direction line shall be marked on the casing with red paint.

[0064] S3: Drilling and testing: 1. Drilling rig in place: After the casing is buried, check the working status of the rotary drilling rig. If it is in good condition, move the rotary drilling rig to the front of the bored pile to be constructed, use the automatic adjustment control system of the drilling rig to level the drilling rig, adjust the verticality of the drill rod, and align it with the pile position, then start the drilling machine for drilling construction; when drilling, introduce advanced drilling control systems, which include automatic positioning and automatic deviation correction systems to ensure the accuracy and verticality of the drilling holes, use data monitoring and sensor technology to monitor the changes in soil layers and the stability of the hole wall during the drilling process in real time, so as to adjust the drilling parameters in time, and use more efficient mud pumps and larger capacity mud pools when drilling holes; improve the circulation speed and utilization rate of mud, and use new power systems to drive the drilling rig to operate; new power systems use electric and hybrid power to reduce energy consumption and emissions;

[0065] It should be noted that the verticality of the drill rod should be checked with a level or plumb bob at least once a day and should not exceed 5 cm to ensure that the verticality deviation of the construction pile hole is less than 0.5%. After the pile driver is centered and leveled in place, the positioning system of the pile driver should be locked to ensure that there is no centering deviation. Before drilling, check whether the drill bit diameter is consistent with the pile diameter. The drill bit diameter can be 2 to 3 cm smaller than the pile diameter.

[0066] 2. Hole detection: During the drilling process of the rotary drilling rig, the drilling depth is measured regularly. When it approaches the designed depth, the drilling speed is slowed down and the drilling is stopped after reaching the designed depth. The steel bar detection cage and measuring rope are lowered to check the hole diameter and hole depth;

[0067] The construction sequence of drilling holes is as follows: the supporting pile structure adopts interlocking piles, and the piles are arranged in an alternating manner according to a reinforced concrete B pile and a plain concrete A pile. The piles are divided into two types of piles, A and B, according to the order of construction. The unreinforced A piles are constructed first, and the B piles need to be reinforced. When the B piles are constructed, the concrete of the intersection of the adjacent A piles is cut off for interlocking. The strength of the A piles is required to reach more than 85% before the B piles can be constructed. The general construction principle is to construct the A piles first and then the B piles. The construction process is: A1-A2-B1-A3-B2-A4-B3..., such as Figure 4 shown.

[0068] The construction process of drilling rig drilling includes:

[0069] S3.1: Preparation of slurry materials: Bentonite is used as the slurry material. Bentonite is sampled before use, and mud proportion test and physical analysis are carried out. Qualified bentonite is put into the mud mixer and fully stirred for 6 to 8 minutes, and then stored in the pool for more than 24 hours to fully hydrate it before delivery;

[0070] According to the soil conditions on site, some mud is formed in the process of pile formation; in the process of cleaning the trench, the mud is precipitated in the sedimentation tank and a part of the high-quality mud is reserved; after underwater concrete pouring, a part of the mud is replaced by concrete and then precipitated or chemically treated, and some mud that meets the requirements is retained; the main components of bentonite slurry are bentonite, admixtures and water. The admixtures mainly include carboxymethyl cellulose and caustic soda, which respectively increase the viscosity of the mud and increase the negative charge adsorbed on the surface of bentonite particles. The bentonite slurry formula is as follows: Figure 6 As shown;

[0071] S3.2: Mud circulation system: The mud circulation system includes: a large mud pool, a mud sedimentation pool, a mud separator, a mud pump, and a high-pressure submersible pump. During the drilling process: the mud in the mud pool is directly pumped into the pile in the hole by a mud pump. After the hole is completed, the mud in the hole is pumped to the mud separator, and the slag slurry is separated by the mud separator. The mud is stored in the mud pool for use in the construction of the next pile hole section. The mud circulation during the cleaning process is pumped by the high-pressure submersible pump to the sand separator for sand separation. After the mud is qualified, it flows back to the hole. For the mud circulation of underwater concrete pouring, two mud pumps are placed near the concrete pouring hole to pump the mud to the mud pool and the slurry storage tank during concrete pouring.

[0072] S3.3: Drilling construction: 1. Align the drill bit, lower the drill bit, touch the ground, rotate, and excavate. Use the drill bit's own weight or the pressurized cylinder as the drilling pressure; 2. When the drill bit is filled with debris, lift it up. While paying attention to the changes in the groundwater level, add mud into the hole, and always keep the water level in the pile hole about 1m away from the top of the pile hole; 3. Lift and open the drill bit bottom plate, dump the soil in the drill bit to one side of the hole, and transport it away after the hole is completed; 4. Close the valve of the drill bit bottom plate, turn the drill bit back to the drilling site, align it with the hole position, and then lower it into the hole to continue drilling; 5. When the drilling depth is close to the designed hole bottom elevation, add water in time to adjust various indicators such as mud density, and clean the hole while drilling;

[0073] It should be noted that 1. When the rotary drilling machine is in place accurately, the penetration of each drilling is controlled at about 60cm. At the beginning, the rotary drilling speed should be slowed down, and the bucket should be placed steadily and lifted slowly. Especially during the rotary drilling process of 5 to 8m from the hole mouth, the verticality should be monitored through the control panel. If there is any deviation, it should be corrected in time. When drilling, the minimum distance between the soil poured out by the drill bucket and the hole mouth should be greater than 6m, and it should be cleared in time. If there is abundant groundwater in the pile hole, drilling can only be started after the mud preparation is qualified, and the mud should be replenished synchronously according to the drilling speed to keep the required mud surface height unchanged;

[0074] 2. When drilling, if inclined holes, curved holes, shrinkage holes, collapsed holes or ground subsidence occur, drilling should be stopped and construction can only be continued after measures are taken;

[0075] 3. When drilling into hard layers, if the depth of each penetration is too small and there is too little drilling debris in the bucket, you can use a small-diameter cylindrical toothed drill bucket to drill a small hole first, and then use the drill bucket to expand the hole and drill. You can also use a short spiral drill and then lower the drill bucket to pick up the debris. The drilling speed should be determined according to the soil layer conditions, hole diameter, hole depth, drilling rig load, and hole quality. When drilling in gravel, sandy eggs, and pebbles, in order to protect the stability of the hole wall, you can put a proper amount of clay balls into the hole in advance. The bottom plate of the drill bit that is lowered into the hole must be equipped with a closed valve plate to prevent gravel from leaking into the hole from the bottom when the drill is lifted;

[0076] S4: Initial hole cleaning: After drilling to the designed hole depth and conducting hole detection, lower the drill bucket to the bottom of the hole and rotate it mechanically for several circles to put the loose soil at the bottom of the hole into the bucket as much as possible. After drilling, the loose soil at the bottom of the hole still needs to be cleaned; the initial hole cleaning uses a sediment treatment drill bucket to discharge the sediment. After the hole cleaning is completed, the sediment thickness at the bottom of the hole meets the following requirements: the sediment thickness of the bite pile is less than 200mm, and the sediment thickness of the engineering pile is ≤50mm;

[0077] S5: Steel cage installation: 1. Steel cage production: After the steel bars arrive at the site, the steel bar team cuts the materials according to the requirements of the design drawings under the guidance of the on-site construction workers, and then produces the steel cage; the steel cage is produced using automated and modular steel cage production technology to improve production efficiency and the quality of the steel cage.

[0078] 2. Lifting of steel cage: After the bored pile is bored and the first hole cleaning is completed, the steel cage made according to the design requirements and accepted shall be placed in the hole. When lowering, the steel cage shall be kept straight and it is strictly forbidden to swing and collide with the hole wall. After it is in place, the positioning steel bars shall be welded. During the lifting and installation, auxiliary tools such as guide devices and positioners shall be used to ensure the accurate installation of the steel cage.

[0079] S6: Lowering the conduit: After the steel cage is lowered to the designed depth, immediately lower the concrete delivery conduit, completely lower the conduit to the bottom of the hole, and after checking that it is correct, gently lift the conduit, control the bottom opening to be 0.25-0.4m away from the bottom of the hole, and be located in the center of the borehole; the conduit is lowered using a special spiral threaded conduit with an inner diameter of 300mm, a middle section length of 2.6m, a lowest section length of 4-5m, and equipped with 0.5m, 1m, 1.5m non-standard sections. The axis difference after the conduit is assembled shall not exceed the borehole depth. 0.5% and not more than 10cm, the test pressure is 1.5 times the hydrostatic pressure at the bottom of the hole, the effective radius of the conduit is generally 3-4m, and the length of the first section of the bottom pipe of the conduit should not be less than 4m. It should be noted that before the conduit is used, in addition to carefully checking its specifications, quality and splicing structure, it should be tested and pressure tested. The length of the pressure test conduit should meet the needs of the longest pile casting. The conduits are numbered and segmented from bottom to top, and the combination order of the conduits is strictly maintained. Each group of conduits cannot be mixed;

[0080] S7: Secondary hole cleaning: After the steel cage and conduit are installed, the hole depth is measured again. If the thickness of the sediment in the hole does not meet the design requirements, secondary hole cleaning is required. Add clean water to the hole to circulate the mud, and install a mud separator until the mud in the hole meets the design requirements; after the pile is formed, the actual effective pile length shall not be less than the designed effective pile length, the thickness of the sediment in the hole shall be <200mm for the bite pile and ≤50mm for the engineering pile, the mud density within 500mm of the bottom of the hole shall be less than 1.25, the sand content shall be ≤8%, and the viscosity shall be ≤28;

[0081] S8: Pouring underwater concrete:

[0082] S8.1: After the hole is cleaned to the required level, the concrete pouring conduit should be lowered to carry out the concrete pouring work;

[0083] S8.2: Before pouring concrete, the concrete conduit must be firmly installed, the sealing ring must be properly placed, and the bottom of the conduit must be 0.3-0.5m away from the bottom of the hole;

[0084] S8.3: The initial pouring volume of concrete shall ensure that the bottom of the conduit is buried 1.0m below the concrete surface during the initial pouring;

[0085] S8.4: The buried depth of the conduit should be 2-6m. Measure the buried depth of the conduit and the height difference of the concrete surface inside and outside the conduit, and fill in the underwater concrete pouring record;

[0086] S8.5: Concrete shall be poured continuously. The pouring time of each pile shall be controlled according to the initial setting time of the initial batch of concrete. All failures during the pouring process shall be recorded and filed;

[0087] S8.6: Control the amount of the last pouring, so that the pile top is not too low, and the height of the grout removed is such that the exposed pile top concrete reaches the design strength value;

[0088] The concrete pouring adopts C45 and C20 underwater commercial concrete, the slump of concrete is 180-200mm, the filling coefficient of concrete pouring is ≥1.0, and the slump should be controlled at 18-22cm; when pouring the first batch of concrete, the distance from the lower end of the conduit to the bottom of the hole is 0.25-0.4m, and the first batch of concrete reserves in the storage hopper ensure that the depth of the conduit buried in the concrete after pouring is not less than 1.0m, and the initial setting time of concrete should be greater than the whole pile pouring time. After the concrete pouring is completed, the casing should be pulled out in time. When pulling out the tube for the last time, the conduit should be slowly pulled out to avoid the upper mud in the hole being pressed into the pile. During the concrete pouring process, the elevation of the concrete surface should be measured in time, and the over-pouring height should be strictly controlled to ensure the effective pile length and the height of the pile head;

[0089] S9: Pull out the casing and move the machine: After the concrete pouring is completed, remove the casing and move the rotary drilling rig to the next cast-in-place pile for construction;

[0090] S10: Chiseling pile head: After the pile is formed and the strength reaches the requirement, the earth and stone around the pile are excavated to reach the bottom elevation of the cap, and the pile head is processed manually to reach the designed pile top elevation and meet the design strength requirements;

[0091] S11: Pile foundation quality inspection: Ultrasonic testing is used to inspect the pile body quality of interlocking piles. The number of piles to be inspected is 20% of the total number and shall not be less than 5. When the pile body integrity category determined by ultrasound is Class III or Class IV, the core drilling method should be used for additional inspection. The number of piles to be inspected is 1% of the total number of piles, 1 hole is drilled for each pile, and shall not be less than 3 piles.

[0092] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0093] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0094] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. Changes and variations made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A deep rotary bored pile construction method, characterized in that: The steps include: S1: Construction preparation: 1). Measurement and positioning: Carry out unit project positioning measurement according to the control point coordinates provided by the construction unit, and then use lime to lay out the edge line of the concrete guide wall according to the design drawings; 2). Guide wall construction: Concrete or reinforced concrete guide wall is constructed on the top of the pile. The guide wall is 1.2m wide on each side, 25cm thick, 1220cm in diameter, with a strength grade of C20 concrete. The steel bars are arranged strictly according to the design requirements. 3) Construction management preparation: Establish an information management platform for rotary bored pile construction to monitor the construction process in real time, analyze data and provide decision support. Use BIM technology to simulate and optimize the construction process. Introduce robots, drones and other intelligent equipment to assist construction personnel in on-site operations and monitoring. Use artificial intelligence and big data technology to predict and warn of quality problems during the construction process. S2: Casing burial: Casing shall be set according to the pile position. The inner diameter of the casing shall be 100mm larger than the drill bit diameter. The casing position shall be correctly and stably buried. The deviation between the center of the casing and the center of the pile position shall not be greater than 50mm. The deviation of the inclination shall not be greater than 1%. Clay shall be used to fill the space between the casing and the pit wall. The casing shall be buried by the static pressure method of the rotary drilling rig. S3: Drilling and testing: 1). Drilling rig in place: After the casing is buried, check the working status of the rotary drilling rig. If it is in good condition, move the rotary drilling rig to the front of the bored pile to be constructed. Use the automatic adjustment control system of the drilling rig to level the drilling rig, adjust the verticality of the drill rod, and align it with the pile position, then start the drilling rig for drilling construction; when drilling, introduce advanced drilling control system to monitor the soil layer changes and hole wall stability in real time during the drilling process, and use more efficient mud pumps and larger capacity mud pools when drilling; the new power system drives the drilling rig to operate; 2). Hole detection: During the drilling process of the rotary drilling rig, the drilling depth is measured regularly. When it approaches the designed depth, the drilling speed is slowed down and the drilling is stopped after reaching the designed depth. The steel bar detection cage and measuring rope are lowered to check the hole diameter and hole depth; S4: Initial hole cleaning: After drilling to the designed hole depth and conducting hole testing, lower the drill bucket to the bottom of the hole and rotate it mechanically for several circles to put as much loose soil as possible into the bucket. After pulling out the drill, the loose soil at the bottom of the hole still needs to be cleaned; S5: Steel cage installation: 1). Steel cage production: After the steel bars arrive at the site, the steel bar team cuts the steel bars according to the design drawings and under the guidance of the on-site construction workers, and then produces the steel cage; the steel cage is produced using automated and modular steel cage production technology; 2). Lifting of steel cage: After the bored pile is bored and the first hole cleaning is completed, the steel cage made according to the design requirements and accepted will be placed in the hole. When lowering, the steel cage should be kept straight and it is strictly forbidden to swing and collide with the hole wall. After it is in place, the positioning steel bars are welded. Auxiliary tools such as guide devices and positioners are used during lifting and installation; S6: Lowering the guide tube: After the steel cage is lowered to the designed depth, immediately lower the concrete conveying guide tube, completely lower the guide tube to the bottom of the hole, and after checking that it is correct, gently lift the guide tube, control the bottom opening to be 0.25 to 0.4m away from the bottom of the hole and located in the center of the borehole; S7: Secondary hole cleaning: After the steel cage and conduit are installed, the hole depth is measured again. If the thickness of the sediment in the hole does not meet the design requirements, secondary hole cleaning is required. Add clean water to the hole to circulate the mud, and install a mud separator until the mud in the hole meets the design requirements; S8: Pouring underwater concrete: S8.1: After the hole is cleaned to the required level, the concrete pouring conduit should be lowered to carry out the concrete pouring work; S8.2: Before pouring concrete, the concrete conduit must be firmly installed, the sealing ring must be properly placed, and the bottom of the conduit must be 0.3-0.5m away from the bottom of the hole; S8.3: The initial pouring volume of concrete shall ensure that the bottom of the conduit is buried 1.0m below the concrete surface during the initial pouring; S8.4: The buried depth of the conduit should be 2-6m. Measure the buried depth of the conduit and the height difference of the concrete surface inside and outside the conduit, and fill in the underwater concrete pouring record; S8.5: Concrete shall be poured continuously. The pouring time of each pile shall be controlled according to the initial setting time of the initial batch of concrete. All failures during the pouring process shall be recorded and filed; S8.6: Control the amount of the last pouring, so that the pile top is not too low, and the height of the grout removed is such that the exposed pile top concrete reaches the design strength value; S9: Pull out the casing and move the machine: After the concrete pouring is completed, remove the casing and move the rotary drilling rig to the next cast-in-place pile for construction; S10: Chiseling pile head: After the pile is formed and the strength reaches the requirement, the earth and stone around the pile are excavated to reach the bottom elevation of the cap, and the pile head is processed manually to reach the designed pile top elevation and meet the design strength requirements; S11: Pile foundation quality inspection: Ultrasonic testing is used to inspect the pile body quality of interlocking piles. The number of piles to be inspected is 20% of the total number and shall not be less than 5. When the pile body integrity category determined by ultrasound is Class III or Class IV, the core drilling method should be used for additional inspection. The number of piles to be inspected is 1% of the total number of piles, 1 hole is drilled for each pile, and shall not be less than 3 piles.

2. A deep rotary bored pile construction method according to claim 1, characterized in that: The guide wall construction process in S1 is as follows: S1.1: Leveling the site: clearing the surface debris and filling and rolling the trenches for the migration of ground pipelines; S1.2: Measure and lay out the pile positions: Calculate the coordinates of the center line of the pile row according to the coordinates provided in the design drawings, use the total station to carry out field layout according to the ground wire control points, and make pile guards as the control center line for the guide wall construction; S1.3: Excavation of guide wall trench: After the stake position layout line meets the requirements, the trench can be excavated. Mechanical excavation is adopted, and manual construction is coordinated. The excavation depth is 15cm below the ground surface, so that the top of the guide wall is higher than the original ground. After the excavation is completed, the center line is immediately introduced under the trench to control the bottom formwork and template construction; S1.4: Formwork construction: The formwork adopts self-made integral steel formwork, the template diameter of the reserved positioning hole of the guide wall is 1220cm, and the diameter of the pipe sleeve is enlarged by 2cm. The formwork reinforcement adopts 5×10 square wood support, and the support spacing is not more than 1 meter; S1.5: Concrete construction: The guide wall is made of commercial concrete, which is manually poured into the mold. The concrete is poured symmetrically and alternately on both sides. The vibrator is an inserted B50 vibrator with a vibration interval of about 600mm. The mold is removed after the concrete strength reaches 70%. After the mold is removed, the opposite support is immediately added to ensure that the guide wall remains stable during construction. The deviation between the center of the reserved hole in the guide wall and the center of the pile position is not more than 20mm.

3. A deep rotary bored pile construction method according to claim 1, characterized in that: The construction sequence of drilling holes in S3 is as follows: the supporting pile structure adopts interlocking piles, the piles are arranged in a manner of spacing out one reinforced concrete B pile and one plain concrete A pile, the piles are divided into two types of piles A and B according to the order of construction, the unreinforced A piles are constructed first, and the B piles need to be reinforced, and when the B piles are constructed, the concrete of the intersecting parts of the adjacent A piles is cut off for interlocking, and the strength of the A piles is required to reach 85% or more before the B piles can be constructed.

4. A deep rotary bored pile construction method according to claim 1, characterized in that: The construction process of drilling holes in S3 includes: S3.1: Preparation of slurry materials: Bentonite is used as the slurry material. Before use, bentonite is sampled, subjected to mud ratio test and physical analysis. Qualified bentonite is put into a mud mixer and fully stirred for 6-8 minutes, and then placed in a pool for more than 24 hours to fully hydrate it before delivery. According to the soil conditions on site, part of the mud is formed during the pile formation process. During the trough cleaning process, the mud is precipitated in the sedimentation tank and a part of high-quality mud is reserved. After underwater concrete pouring, a part of the mud is replaced by concrete and then precipitated or chemically treated, and a part of the mud that meets the requirements is retained. S3.2: Mud circulation system: The mud circulation system includes: a large mud pool, a mud sedimentation pool, a mud separator, a mud pump, and a high-pressure submersible pump. During the drilling process: the mud in the mud pool is directly pumped into the pile in the hole by a mud pump. After the hole is completed, the mud in the hole is pumped to the mud separator, and the slag slurry is separated by the mud separator. The mud is stored in the mud pool for use in the construction of the next pile hole section. The mud circulation during the cleaning process is pumped by the high-pressure submersible pump to the sand separator for sand separation. After the mud is qualified, it flows back to the hole. For the mud circulation of underwater concrete pouring, two mud pumps are placed near the concrete pouring hole to pump the mud to the mud pool and the slurry storage tank during concrete pouring. S3.3: Drilling construction:

1. Align the drill bit, lower the drill bit, touch the ground, rotate, and excavate. Use the drill bit's own weight or the pressurized oil cylinder as the drilling pressure; 2. When the drill bit is filled with debris, lift it up. While paying attention to the changes in the groundwater level, add mud into the hole, and always keep the water level in the pile hole about 1m away from the top of the pile hole; 3. Lift and open the drill bit bottom plate, dump the soil in the drill bit to one side of the hole, and transport it away after the hole is completed; 4. Close the valve of the drill bit bottom plate, turn the drill bit back to the drilling site, align it with the hole position, and then lower it into the hole to continue drilling; 5. When the drilling depth is close to the designed hole bottom elevation, add water in time to adjust various indicators such as mud density, and clean the hole while drilling.

5. A deep rotary bored pile construction method according to claim 1, characterized in that: The initial hole cleaning in S4 uses a sediment treatment drill bucket to discharge sediment. After the hole cleaning is completed, the sediment thickness at the bottom of the hole meets the following requirements: the sediment thickness of the bite pile is less than 200 mm, and the sediment thickness of the engineering pile is ≤50 mm.

6. A deep rotary bored pile construction method according to claim 1, characterized in that: The S6 intermediate conduit is lowered using a special spiral threaded conduit with an inner diameter of 300 mm. The middle section is 2.6 m long and the lowest section is 4-5 m long. It is equipped with non-standard sections of 0.5 m, 1 m, and 1.5 m. The axis difference after the conduit is assembled does not exceed 0.5% of the borehole depth and is not greater than 10 cm. The test pressure is 1.5 times the hydrostatic pressure at the bottom of the hole.

7. A deep rotary bored pile construction method according to claim 1, characterized in that: After the pile is formed in S7, the actual effective pile length shall not be less than the designed effective pile length, the thickness of the sediment in the hole shall be <200mm for the bite pile and ≤50mm for the engineering pile, the mud density within 500mm from the bottom of the hole shall be less than 1.25, the sand content shall be ≤8%, and the viscosity shall be ≤28.

8. A deep rotary bored pile construction method according to claim 1, characterized in that: The pouring of concrete in S8 adopts C45 and C20 underwater commercial concrete, the slump of concrete is 180-200mm, the filling coefficient of concrete pouring is ≥1.0, and the slump should be controlled at 18-22cm.

9. A deep rotary bored pile construction method according to claim 8, characterized in that: When pouring the first batch of concrete in S8, the distance from the lower end of the conduit to the bottom of the hole is 0.25-0.4m, and the first batch of concrete reserves in the storage hopper ensure that the depth of the conduit buried in the concrete after pouring is not less than 1.0m, and the initial setting time of the concrete should be greater than the entire pile pouring time.

10. A deep rotary bored pile construction method according to claim 1, characterized in that: The drilling control system in the S3 includes automatic positioning and automatic deviation correction systems to ensure the accuracy and verticality of drilling. The new power system in the S3 uses electric power, hybrid power, etc.

Images