CN-122013756-A - Pile foundation construction process applied to loose foundation

Abstract

The invention discloses a pile foundation construction process applied to a loose foundation, which comprises the following steps of S1, construction preparation, S2, embedding of a steel pile casing, S3, primary drilling, S4, pre-mixed solid fluidized soil pouring, S5, secondary drilling, S6, hole cleaning operation, S7, reinforcement cage construction, S8, concrete pouring, and S9, finished product maintenance and detection. The method has the advantages that the pre-mixed solid fluidized soil is poured into the primary hole forming through primary hole forming, the pre-mixed solid fluidized soil is utilized to replace traditional concrete, the pre-filling of the primary hole forming is realized, the hole collapse of the primary hole forming is avoided, the concrete consumption and the additional cost are reduced, then secondary hole forming is carried out on the pre-mixed solid fluidized soil pile, a reinforcement cage is arranged below the secondary hole forming, the construction of a pile foundation is realized, the hole collapse problem in a pebble layer with poor grading is effectively solved, the concrete consumption is obviously reduced, and the double optimization of the construction cost and the construction period is realized.

Inventors

• LI CONG
• PAN TIANHUA
• ZHAO XIAOBIN
• ZHOU XIAOJIE
• ZHANG ZHENGWEI
• LIU WANXI
• WANG KAI
• LIU WEI
• Zhuang Jiyou
• Wu Chuanxue
• WU HEYANG
• ZHANG JIAN
• ZHENG YANG
• LEI XIANGHUA
• LI FENG
• YANG FAN
• WANG KUO
• YANG TIANXIN
• SUN PENG
• Chi Yongyong
• LU JINJUN

Assignees

• 北京市第五建筑工程集团有限公司

Dates

Publication Date

20260512

Application Date

20260324

Claims (8)

1. 1. A pile foundation construction process applied to loose foundations is characterized by comprising the following steps: S1, construction preparation, namely clearing obstacles in a construction area, leveling and compacting a field, ensuring the operation stability of a drilling machine, accurately setting out a pile position by adopting a total station coordinate method, controlling the error within +/-2 cm, and simultaneously setting cross pile protectors at the positions of 1 time and 2 times of the pile diameter in the center of the pile position, wherein the pile protectors are marked by reflecting patches; S2, burying a steel pile casing, wherein the inner diameter of the steel pile casing is 20-40cm larger than the diameter of a designed pile, burying the steel pile casing in the ground, and the top surface of the steel pile casing is 0.3m higher than the construction ground, lifting the steel pile casing after digging holes by adopting a rotary drilling rig, adjusting the center of the pile casing to coincide with the pile position through a pile casing pull line, controlling the gradient to be within 1%, backfilling clay symmetrically around the pile casing and footing, tamping in layers, rechecking the plane position and verticality again, and measuring the top elevation of the pile casing to calculate the designed hole depth; S3, drilling holes for the first time, calibrating the verticality of a drill rod by using a self-contained leveling system after the drilling machine is in place, locking the drill rod after rechecking of a level bar is completed, controlling the drilling speed to be 20-30 m/h, adjusting the drilling pressure to be 10-15 tons, taking slag samples every 2m of drilling to record geological conditions, and switching a low-speed impact mode when a boulder is met, so that the drill bit is prevented from deflecting; s4, pouring pre-mixed solid fluidized soil, namely cleaning drilled holes, thoroughly cleaning out a collapsed hole area, removing collapsed soil and sundries until the designed hole depth, and pouring the pre-mixed solid fluidized soil into the cleaned hole channel to ensure that pouring is compact; S5, secondary drilling is carried out, after the drilling machine is in place, the position of the drilling rod is adjusted, the center of the drilling rod and the center of the solid fluidized soil foundation pile are positioned in the same straight line, then drilling is carried out, and a hole is drilled in the center of the solid fluidized soil foundation pile; s6, hole cleaning, namely, a reverse circulation conduit is lowered to a position 30-50cm above the hole bottom and is connected with a vacuum pump, hole bottom sediment is pumped out through reverse suction, if large pebble sediment is met, the large pebble sediment is matched with a hole cleaning barrel to be mechanically grabbed, and repeated operation is carried out until the sediment thickness reaches the standard; S7, constructing the reinforcement cage, namely vertically lowering the reinforcement cage by using a crane and matching with a guide frame, wherein the lowering speed is controlled to be 0.5-1m/min, collapse or deformation of the reinforcement cage caused by collision with the hole wall is avoided, verticality is rechecked for a plurality of times in the installation process, the center of the reinforcement cage is ensured to coincide with the center of a pile position, and after the reinforcement cage is in place, the reinforcement cage is firmly fixed, and floating or deflection during concrete pouring is prevented; S8, pouring concrete, namely pouring the concrete by adopting a conduit method, wherein the diameter of the conduit is adapted to the diameter of the pile, performing a water tightness test before installation, checking sediment at the bottom of the hole again before pouring, cleaning the hole twice if the sediment exceeds the standard, controlling the slump of the concrete within a reasonable range, keeping the burial depth of the conduit at 2-6m all the time during pouring, lifting the conduit at a constant speed, avoiding the conduit from being pulled out of the concrete surface to cause pile breakage, pouring the concrete to be 0.5-1.0m above the designed elevation of the pile top, ensuring the strength of the concrete at the pile top to reach the standard, and continuously performing the pouring process, and recording the pouring quantity and the pouring time; S9, curing and detecting finished products, timely covering and curing after concrete pouring is completed, curing time is not less than 14 days, detecting pile body integrity by adopting a low strain reflection wave method or an ultrasonic method after pile forming, and carrying out static load test according to design requirements by bearing capacity detection to ensure that pile foundations meet engineering use requirements.
2. 2. The pile foundation construction process for loose foundations of claim 1, wherein in step S5, bentonite slurry circulation wall protection is adopted during secondary drilling, the slurry density is maintained at 1.1-1.2g/cm <3 >, and if the permeability of pebble layer is extremely high, slurry loss is caused, and polymer admixture is added to enhance the bonding force.
3. 3. The pile foundation construction process for loose foundations of claim 1, wherein the premixed solid fluidized soil consists of slag soil, cement, curing agent and water, and the mass ratio of the components is 100:8:2:25.
4. 4. A pile foundation construction process for loose foundations according to claim 1, wherein in step S4, before pouring the ready-mixed solid fluidized soil, the steel wire mesh (1) is wound into a cylindrical shape, a section of steel wire mesh (1) is connected and then is lowered into the primary hole, and then pouring of the ready-mixed solid fluidized soil is performed.
5. 5. A pile foundation construction process for loose foundations according to claim 4, wherein the diameter of the cylindrical shape of the rolled steel wire mesh (1) is 3-5cm smaller than the diameter of the primary drilled hole.
6. 6. The pile foundation construction process for loose foundations according to claim 5, wherein a locking piece (2) is arranged between two adjacent sections of steel wire nets (1), the locking piece (2) comprises a pair of locking plates (21) and a pair of locking hooks (22), the locking plates (21) are arranged in an up-and-down layered mode, the locking hooks (22) are arranged on one side, away from each other, of each locking plate (21) and are used for hooking the upper end and the lower end of each steel wire net (1), clamping teeth (23) are arranged on one side, away from the locking hooks (22), of each locking plate (21), and the clamping teeth (23) are used for penetrating the corresponding locking plates (21) and are clamped and fixed with the locking plates (21).
7. 7. The pile foundation construction process for loose foundations according to claim 6, wherein the closed opening positions of two adjacent sections of steel wire nets (1) are arranged in a staggered manner.
8. 8. The pile foundation construction process for loose foundations according to claim 7, wherein the lower end of the steel wire mesh (1) is provided with an inserting rod (11), and the upper end is provided with an inserting ring (12) for inserting the inserting rod (11).

Description

Pile foundation construction process applied to loose foundation Technical Field The invention relates to the field of building construction, in particular to a pile foundation construction process applied to loose foundations. Background Along with the development of the building industry to high rise and large size, the weight of a building main body is continuously increased, the requirement on the bearing capacity of a foundation is increasingly severe, and the pile foundation has good bearing performance and is widely applied to various building engineering. However, partial engineering construction positions are remote, geological conditions are complex, and especially when pile foundations pass through pebble beds with poor grading, problems such as instant slurry loss and pore canal collapse are easy to occur in the drilling process, and normal construction of the pile foundations is affected. In the traditional hole collapse treatment process, a method of lengthening a pile casing, backfilling clay or directly pouring concrete for filling is mostly adopted. If the lengthened pile casing is adopted, only shallow hole collapse can be dealt with, effective support is difficult to form by backfilling clay, the dosage of concrete can be increased by times by directly pouring the concrete, the construction cost is greatly improved, the whole engineering progress can be influenced by overlong treatment period, and the improvement is needed. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a pile foundation construction process applied to a loose foundation, which can effectively solve the problem of hole collapse in a pebble layer with poor grading, remarkably reduce the concrete consumption and realize double optimization of construction cost and construction period. The technical aim of the invention is achieved by the following technical scheme that the pile foundation construction process applied to the loose foundation comprises the following steps: S1, construction preparation, namely clearing obstacles in a construction area, leveling and compacting a field, ensuring the operation stability of a drilling machine, accurately setting out a pile position by adopting a total station coordinate method, controlling the error within +/-2 cm, and simultaneously setting cross pile protectors at the positions of 1 time and 2 times of the pile diameter in the center of the pile position, wherein the pile protectors are marked by reflecting patches; S2, burying a steel pile casing, wherein the inner diameter of the steel pile casing is 20-40cm larger than the diameter of a designed pile, burying the steel pile casing in the ground, and the top surface of the steel pile casing is 0.3m higher than the construction ground, lifting the steel pile casing after digging holes by adopting a rotary drilling rig, adjusting the center of the pile casing to coincide with the pile position through a pile casing pull line, controlling the gradient to be within 1%, backfilling clay symmetrically around the pile casing and footing, tamping in layers, rechecking the plane position and verticality again, and measuring the top elevation of the pile casing to calculate the designed hole depth; S3, drilling holes for the first time, calibrating the verticality of a drill rod by using a self-contained leveling system after the drilling machine is in place, locking the drill rod after rechecking of a level bar is completed, controlling the drilling speed to be 20-30 m/h, adjusting the drilling pressure to be 10-15 tons, taking slag samples every 2m of drilling to record geological conditions, and switching a low-speed impact mode when a boulder is met, so that the drill bit is prevented from deflecting; s4, pouring pre-mixed solid fluidized soil, namely cleaning drilled holes, thoroughly cleaning out a collapsed hole area, removing collapsed soil and sundries until the designed hole depth, and pouring the pre-mixed solid fluidized soil into the cleaned hole channel to ensure that pouring is compact; S5, secondary drilling is carried out, after the drilling machine is in place, the position of the drilling rod is adjusted, the center of the drilling rod and the center of the solid fluidized soil foundation pile are positioned in the same straight line, then drilling is carried out, and a hole is drilled in the center of the solid fluidized soil foundation pile; s6, hole cleaning, namely, a reverse circulation conduit is lowered to a position 30-50cm above the hole bottom and is connected with a vacuum pump, hole bottom sediment is pumped out through reverse suction, if large pebble sediment is met, the large pebble sediment is matched with a hole cleaning barrel to be mechanically grabbed, and repeated operation is carried out until the sediment thickness reaches the standard; S7, constructing the reinforcement cage, namely vertically lowering the reinforcement cage by using a cra