CN112281894A - Pile foundation construction method - Google Patents

Abstract

The invention discloses a pile foundation construction method which comprises pile foundation engineering construction plane arrangement, pile foundation engineering construction area division, pile foundation construction sequence and construction direction determination, bored pile construction and lime-soil compaction pile construction. The invention has the beneficial effects that: the construction method has the advantages that the construction area is divided, synchronous construction can be carried out, the construction progress is improved, the completion of pile foundation construction within one month is guaranteed, labor force is effectively arranged to enter and exit from the site according to the engineering quantity and the size of a working face in different construction stages, so that labor force resources are fully utilized, two construction methods of bored pile construction and lime-soil compaction pile construction are selected according to different construction foundations during construction, selection can be made in a targeted mode, and different construction requirements are met.

Description

Pile foundation construction method

Technical Field

The invention relates to pile foundation construction, in particular to a pile foundation construction method, and belongs to the technical field of building construction.

Background

Along with the continuous acceleration of urbanization construction pace, high-rise buildings and small high-rise buildings are continuously increased, pile foundation construction is widely applied, a single construction team is often adopted for construction of the existing pile foundation construction method, the construction progress is slow, in addition, for different foundations, only one type of cast-in-situ bored pile is often selected for construction, and an appropriate pile foundation cannot be selected for construction according to different foundations, so that the pile foundation construction method cannot be applied to construction sites with various types of buildings.

Disclosure of Invention

The present invention is directed to a method of constructing a pile foundation.

The invention realizes the purpose through the following technical scheme: a pile foundation construction method comprises the following steps:

the construction method comprises the steps of firstly, arranging pile foundation engineering construction planes, planning construction site office rooms, living facilities and main trunks in a construction site according to a building construction planning diagram, hardening the construction main trunks in the site by using C20 concrete with the thickness of 200mm, and arranging car washing platforms and three-level sedimentation tanks at entrance and exit gates of the site. The steel reinforcement cage processing factory is arranged at a position near the front side of the field, a flat car is adopted for conveying in the construction process, and a mud pit is arranged;

dividing a pile foundation engineering construction area, dividing the site pile foundation into three construction areas according to the quantity of the pile foundations and the sequence of construction, and arranging a pile foundation operating team in each area to construct engineering piles in a synchronous flow manner;

step three, determining a pile foundation construction sequence and a construction direction, wherein the pile foundation construction sequence is as follows: and (4) transporting the filled soil out of the designated position of the field for storage, using the filled soil for later-stage backfilling, taking the elevation of the field to the same elevation, and then tamping and reinforcing the collapsible loess on the surface layer by adopting a dynamic compaction method. After the foundation stabilization treatment is finished, carrying out engineering pile construction; the construction direction is as follows: adopting propulsion construction and symmetrical construction from the center to two sides;

fourthly, construction of the bored pile, namely, adopting a rotary drilling and expanding machine as construction machinery, firstly calibrating the pile position, drilling by the rotary drilling and expanding machine, then hoisting a reinforcement cage in a pile hole, placing a pouring guide pipe, and performing concrete pouring and pile forming;

and fifthly, constructing lime-soil compaction piles, wherein the lime-soil compaction piles are constructed at the position of the building foundation, the diameter of each pile is 400mm, the length of each pile is 7-15.9 m, and the distance between every two adjacent piles is 1000 mm.

As a still further scheme of the invention: in the second step, the division of the construction area further comprises the division of labor organization and work content: according to the scale of the construction engineering of the engineering station house and the division of the construction areas, each area operation team carries out plane flow line operation; and according to the engineering quantity and the size of the working face at different construction stages, the labor force is effectively arranged to enter and exit the field, so that the labor force resource is fully utilized.

As a still further scheme of the invention: in the fourth step, the construction of the cast-in-situ bored pile comprises the following steps:

(1) pile position lofting, namely adopting a principle from whole to local, adopting a total station instrument to perform accurate lofting of a pile foundation position, and timely rechecking the lofted elevation;

(2) the pile driver is in place, and when the pile driver is in place, the pile driver is aligned with the pile position, so that the vertical stability is ensured, and the inclination and the movement are avoided in the construction process;

(3) the method comprises the steps of forming holes on a pile foundation, starting drilling operation, wherein the drilling operation is carried out slowly and quickly, the footage is 40-50cm each time, determining whether an underground unfavorable stratum exists, if the drilling operation is normal after the footage is 5 m, the footage can be properly increased, the footage is controlled to be 70-90cm each time, after the drilling operation is carried out to a preset depth, idle rotation soil removal is carried out at the hole bottom, then the rotation is stopped, and a drill rod is pulled out of a drilled hole;

(4) steel reinforcement cage preparation and installation, steel reinforcement cage is according to the design drawing preparation, when installing, the steel reinforcement cage of slow movement hangs the steel reinforcement cage to the hole site top, aim at the hole site, hold up steady, slowly transfer, rely on the pulley and the steel reinforcement cage dead weight of first hoisting point, the center that the sight made steel reinforcement cage center and drilling is unanimous, the steel reinforcement cage is laid and is accomplished the back, group's cross on steel reinforcement cage symmetry reinforcing bar, connect the single pile fender pile, draw the cross, with hanging down whether coincidence of two cross-points of inspection. When the requirement is not met, the hanging bars of the reinforcement cage are adjusted to be overlapped;

(5) lay the pipe, according to protecting a section of thick bamboo top elevation, the height of lumber skid is considered to hole bottom elevation, calculates the required length of pipe, tries to piece together the pipe, and the pipe adopts crane cooperation manual installation, and when the pipe was laid, the eye-sight, manual fit are held up steady and are made the position to live in the steel reinforcement cage center, then steadily sink, prevent to block and hang steel reinforcement skeleton and collision pore wall. When the device is installed, the guide pipe is firstly placed to the bottom of the hole by using a crane, then the guide pipe is lifted by 40cm, the distance between the bottom of the guide pipe and the bottom of the hole is 40cm, after the height of the guide pipe is determined, the height of a guide pipe clamping disc is adjusted by using a sleeper, and the guide pipe is clamped by using the clamping disc;

(6) pouring concrete, wherein the concrete is poured by adopting a hopper after being transported to the site by a tank truck;

(7) and detecting the engineering pile, and detecting the bearing capacity and the integrity of the pile body of the single pile after the concrete strength of the pile body of the test pile reaches the design requirement.

As a still further scheme of the invention: in the fourth step, during pile group foundation construction, when holes are formed in adjacent piles beside concrete just after pouring, the safety distance of the pile is larger than 4 times of the pile diameter or the minimum time interval is not less than 36 hours, and when row-by-row piling is carried out, the propelling direction of piling is changed row-by-row.

As a still further scheme of the invention: the engineering pile detection comprises a low-strain wave velocity method, sound wave transmission detection and static load test detection, the quality of the pile body is jointly detected by adopting the sound wave transmission method and the low-strain wave velocity method, the detection quantity is 30% of the total pile number, and the sound wave transmission detection is not less than 10% of the total pile number. Every stake all sets up 2 ultrasonic detection pipes, steel pipe internal diameter 57mm, wall thickness 3mm, according to sound wave projection method testing result, adopts the core drilling method to detect the engineering stake that pile foundation ultrasonic detection has a problem. The number of the sampling tests in the static load test is not less than 1% of the total number of the piles, and not less than 3.

As a still further scheme of the invention: in the fifth step, the construction of the lime-soil compaction pile comprises the following steps:

(1) and the construction sequence

According to relevant regulations and technical requirements, the construction sequence of the lime-soil compaction piles is that the construction is carried out by adopting a jump driving method of firstly arranging the lime-soil compaction piles in the inner row and then arranging the lime-soil compaction piles in the outer row and then arranging the lime-soil compaction piles at intervals;

(2) setting position for paying off

And (3) leading a pile arranging control line to the periphery of the foundation pit according to a control axis, then releasing the center position of the pile according to construction drawing, marking by using a wood wedge or a lime point, and controlling the deviation of the pile position within 0.4D (D is the diameter of the pile hole). The surveyor should recheck in time, and can form holes according to the pile point after the surveyor is accurate. In order to ensure the accuracy of paying off, the paying off is carried out in the daytime as much as possible, so that the problem of quality caused by paying off errors at night and untimely discovery is avoided;

(3) forming a hole

The lime-soil compaction pile is constructed by adopting a long spiral drilling method, after a drilling machine is in place, a drill bit is aligned to the center of the placed pile, the verticality of a drill rod is corrected from two different directions by using a plumb bob, and after the verticality is determined to be within a standard allowable range, the drill rod is driven into the soil by using a D400 diesel hammer. The depth of the drilled hole is measured from the upward position of the pile tip 1/2 to the designed elevation position, and the drilled hole is marked on a drilling machine by red paint and is lifted to be formed. When the water content is more than 20%, the shrinkage phenomenon is easy to occur, and pore-forming construction cannot be carried out. And tamping and filling in time after pore forming, and avoiding rolling compaction by a drilling machine to avoid upper shrinkage cavity as much as possible. If the shrinkage cavity is caused by rolling, secondary pore-forming is carried out before tamping. After the hole is formed, the loose earth on the ground surface is poked from the center of the hole to the periphery so as to avoid falling into the pile hole to influence the pile forming quality;

(4) mixing with lime soil

Firstly, the soil and the slaked lime are respectively sieved, and the mixed lime soil needs to be tamped in time and cannot be used every other day. Measuring the ash content and the water content of the lime soil before construction every day, and ensuring that the ash content and the water content of the lime soil after mixing meet the requirements;

(5) tamping, tamping

Before filling the pile hole, tamping the bottom of the hole for 3-4 times, then backfilling and tamping the pile by layers by using lime soil under the state of optimal water content, wherein the thickness of the filler is 400-500 mm each time, the material is symmetrically discharged from two directions respectively, so that the phenomenon that the pile body is askew due to uneven filler is avoided, the lifting height of the tamping hammer is not less than 3m, the tamping times are not less than 6 times, and the filler can be filled after being tamped and expanded. Repeating the above steps until reaching the designed elevation. The average compaction factor of the filler should not be lower than 0.97, wherein the minimum compaction factor should not be lower than 0.93, and the bottom of the pores must be tamped before filling;

(6) and detecting the pile body compactness according to the required frequency. Randomly sampling and detecting the average compaction coefficient of the lime soil or soil filler within the pile length range after tamping, wherein the number of sampling detections is not less than 1 percent of the total number of the piles and not less than 9. The average compaction coefficient of soil between piles in the depth of treatment is checked by sampling, the number of detection exploratory wells is not less than 0.3 percent of the total number of piles, and each single project is not less than 3. The bearing capacity test is carried out 14d-28d after the pile is formed, the detection number is not less than 1% of the total pile number, and the static load test of the composite foundation of each monomer engineering is not less than 3 points;

(7) and after the whole construction is finished, the bearing capacity, the compaction effect and the like are detected to meet the design requirements.

The invention has the beneficial effects that: the pile foundation construction method is reasonable in design, construction areas are divided, synchronous construction can be conducted, construction progress is improved, completion of pile foundation construction within one month is guaranteed, labor force is effectively arranged to enter and exit a field according to the engineering quantity and the size of a working face in different construction stages, labor force resources are fully utilized, two construction methods of bored pile construction and lime-soil compaction pile construction are selected according to different construction foundations during construction, selection can be conducted in a targeted mode, and different construction requirements are met.

Drawings

FIG. 1 is a schematic flow chart of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, a method for constructing a pile foundation includes the following steps:

the construction method comprises the steps of firstly, arranging pile foundation engineering construction planes, planning construction site office rooms, living facilities and main trunks in a construction site according to a building construction planning diagram, hardening the construction main trunks in the site by using C20 concrete with the thickness of 200mm, and arranging car washing platforms and three-level sedimentation tanks at entrance and exit gates of the site. The steel reinforcement cage processing factory is arranged at a position near the front side of the field, a flat car is adopted for conveying in the construction process, and a mud pit is arranged;

dividing a pile foundation engineering construction area, dividing the site pile foundation into three construction areas according to the quantity of the pile foundations and the sequence of construction, and arranging a pile foundation operating team in each area to construct engineering piles in a synchronous flow manner;

step three, determining a pile foundation construction sequence and a construction direction, wherein the pile foundation construction sequence is as follows: and (4) transporting the filled soil out of the designated position of the field for storage, using the filled soil for later-stage backfilling, taking the elevation of the field to the same elevation, and then tamping and reinforcing the collapsible loess on the surface layer by adopting a dynamic compaction method. After the foundation stabilization treatment is finished, carrying out engineering pile construction; the construction direction is as follows: adopting propulsion construction and symmetrical construction from the center to two sides;

fourthly, construction of the bored pile, namely, adopting a rotary drilling and expanding machine as construction machinery, firstly calibrating the pile position, drilling by the rotary drilling and expanding machine, then hoisting a reinforcement cage in a pile hole, placing a pouring guide pipe, and performing concrete pouring and pile forming;

and fifthly, constructing lime-soil compaction piles, wherein the lime-soil compaction piles are constructed at the position of the building foundation, the diameter of each pile is 400mm, the length of each pile is 7-15.9 m, and the distance between every two adjacent piles is 1000 mm.

Further, in the embodiment of the present invention, in the second step, the division of the construction area further includes division of labor organization and work content: according to the scale of the construction engineering of the engineering station house and the division of the construction areas, each area operation team carries out plane flow line operation; and according to the engineering quantity and the size of the working face at different construction stages, the labor force is effectively arranged to enter and exit the field, so that the labor force resource is fully utilized.

Further, in the embodiment of the present invention, in the fourth step, the construction of the cast-in-situ bored pile includes the following steps:

(1) pile position lofting, namely adopting a principle from whole to local, adopting a total station instrument to perform accurate lofting of a pile foundation position, and timely rechecking the lofted elevation;

(2) the pile driver is in place, and when the pile driver is in place, the pile driver is aligned with the pile position, so that the vertical stability is ensured, and the inclination and the movement are avoided in the construction process;

(3) the method comprises the steps of forming holes on a pile foundation, starting drilling operation, wherein the drilling operation is carried out slowly and quickly, the footage is 40-50cm each time, determining whether an underground unfavorable stratum exists, if the drilling operation is normal after the footage is 5 m, the footage can be properly increased, the footage is controlled to be 70-90cm each time, after the drilling operation is carried out to a preset depth, idle rotation soil removal is carried out at the hole bottom, then the rotation is stopped, and a drill rod is pulled out of a drilled hole;

(4) steel reinforcement cage preparation and installation, steel reinforcement cage is according to the design drawing preparation, when installing, the steel reinforcement cage of slow movement hangs the steel reinforcement cage to the hole site top, aim at the hole site, hold up steady, slowly transfer, rely on the pulley and the steel reinforcement cage dead weight of first hoisting point, the center that the sight made steel reinforcement cage center and drilling is unanimous, the steel reinforcement cage is laid and is accomplished the back, group's cross on steel reinforcement cage symmetry reinforcing bar, connect the single pile fender pile, draw the cross, with hanging down whether coincidence of two cross-points of inspection. When the requirement is not met, the hanging bars of the reinforcement cage are adjusted to be overlapped;

(5) lay the pipe, according to protecting a section of thick bamboo top elevation, the height of lumber skid is considered to hole bottom elevation, calculates the required length of pipe, tries to piece together the pipe, and the pipe adopts crane cooperation manual installation, and when the pipe was laid, the eye-sight, manual fit are held up steady and are made the position to live in the steel reinforcement cage center, then steadily sink, prevent to block and hang steel reinforcement skeleton and collision pore wall. When the device is installed, the guide pipe is firstly placed to the bottom of the hole by using a crane, then the guide pipe is lifted by 40cm, the distance between the bottom of the guide pipe and the bottom of the hole is 40cm, after the height of the guide pipe is determined, the height of a guide pipe clamping disc is adjusted by using a sleeper, and the guide pipe is clamped by using the clamping disc;

(6) pouring concrete, wherein the concrete is poured by adopting a hopper after being transported to the site by a tank truck;

(7) and detecting the engineering pile, and detecting the bearing capacity and the integrity of the pile body of the single pile after the concrete strength of the pile body of the test pile reaches the design requirement.

Further, in the fourth step of the present invention, during the pile-group foundation construction, when the hole is formed in the adjacent pile beside the concrete just after the concrete is poured, the safety distance should be greater than 4 times the pile diameter or the minimum time interval should not be less than 36 hours, and when the piles are piled row by row, the advancing direction of the piles should be changed row by row.

Further, in the embodiment of the invention, the engineering pile detection comprises a low-strain wave velocity method, a sound wave transmission detection and a static load test detection, the quality of the pile body is jointly detected by adopting the sound wave transmission method and the low-strain wave velocity method, the detection number is 30% of the total pile number, and the sound wave transmission detection is not less than 10% of the total pile number. Every stake all sets up 2 ultrasonic detection pipes, steel pipe internal diameter 57mm, wall thickness 3mm, according to sound wave projection method testing result, adopts the core drilling method to detect the engineering stake that pile foundation ultrasonic detection has a problem. The number of the sampling tests in the static load test is not less than 1% of the total number of the piles, and not less than 3.

Further, in the embodiment of the present invention, in the fifth step, the construction of the lime-soil compaction pile includes the following steps:

(1) and the construction sequence

According to relevant regulations and technical requirements, the construction sequence of the lime-soil compaction piles is that the construction is carried out by adopting a jump driving method of firstly arranging the lime-soil compaction piles in the inner row and then arranging the lime-soil compaction piles in the outer row and then arranging the lime-soil compaction piles at intervals;

(2) setting position for paying off

And (3) leading a pile arranging control line to the periphery of the foundation pit according to a control axis, then releasing the center position of the pile according to construction drawing, marking by using a wood wedge or a lime point, and controlling the deviation of the pile position within 0.4D (D is the diameter of the pile hole). The surveyor should recheck in time, and can form holes according to the pile point after the surveyor is accurate. In order to ensure the accuracy of paying off, the paying off is carried out in the daytime as much as possible, so that the problem of quality caused by paying off errors at night and untimely discovery is avoided;

(3) forming a hole

The lime-soil compaction pile is constructed by adopting a long spiral drilling method, after a drilling machine is in place, a drill bit is aligned to the center of the placed pile, the verticality of a drill rod is corrected from two different directions by using a plumb bob, and after the verticality is determined to be within a standard allowable range, the drill rod is driven into the soil by using a D400 diesel hammer. The depth of the drilled hole is measured from the upward position of the pile tip 1/2 to the designed elevation position, and the drilled hole is marked on a drilling machine by red paint and is lifted to be formed. When the water content is more than 20%, the shrinkage phenomenon is easy to occur, and pore-forming construction cannot be carried out. And tamping and filling in time after pore forming, and avoiding rolling compaction by a drilling machine to avoid upper shrinkage cavity as much as possible. If the shrinkage cavity is caused by rolling, secondary pore-forming is carried out before tamping. After the hole is formed, the loose earth on the ground surface is poked from the center of the hole to the periphery so as to avoid falling into the pile hole to influence the pile forming quality;

(4) mixing with lime soil

Firstly, the soil and the slaked lime are respectively sieved, and the mixed lime soil needs to be tamped in time and cannot be used every other day. Measuring the ash content and the water content of the lime soil before construction every day, and ensuring that the ash content and the water content of the lime soil after mixing meet the requirements;

(5) tamping, tamping

Before filling the pile hole, tamping the bottom of the hole for 3-4 times, then backfilling and tamping the pile by layers by using lime soil under the state of optimal water content, wherein the thickness of the filler is 400-500 mm each time, the material is symmetrically discharged from two directions respectively, so that the phenomenon that the pile body is askew due to uneven filler is avoided, the lifting height of the tamping hammer is not less than 3m, the tamping times are not less than 6 times, and the filler can be filled after being tamped and expanded. Repeating the above steps until reaching the designed elevation. The average compaction factor of the filler should not be lower than 0.97, wherein the minimum compaction factor should not be lower than 0.93, and the bottom of the pores must be tamped before filling;

(6) and detecting the pile body compactness according to the required frequency. Randomly sampling and detecting the average compaction coefficient of the lime soil or soil filler within the pile length range after tamping, wherein the number of sampling detections is not less than 1 percent of the total number of the piles and not less than 9. The average compaction coefficient of soil between piles in the depth of treatment is checked by sampling, the number of detection exploratory wells is not less than 0.3 percent of the total number of piles, and each single project is not less than 3. The bearing capacity test is carried out 14d-28d after the pile is formed, the detection number is not less than 1% of the total pile number, and the static load test of the composite foundation of each monomer engineering is not less than 3 points;

(7) and after the whole construction is finished, the bearing capacity, the compaction effect and the like are detected to meet the design requirements.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (6)

1. A pile foundation construction method is characterized in that: the method comprises the following steps:

firstly, arranging a pile foundation engineering construction plane, planning a construction site office room, a living facility and a main trunk road in a construction site according to a building construction planning diagram, hardening the construction trunk road in the site by using C20 concrete with the thickness of 200mm, arranging a car washing platform and a three-stage sedimentation tank at an entrance and exit gate of the site, arranging a reinforcement cage processing factory at a position near the front side of the site, and adopting a flat car for conveying in the construction process and arranging a mud tank;

dividing a pile foundation engineering construction area, dividing the site pile foundation into three construction areas according to the quantity of the pile foundations and the sequence of construction, and arranging a pile foundation operating team in each area to construct engineering piles in a synchronous flow manner;

step three, determining a pile foundation construction sequence and a construction direction, wherein the pile foundation construction sequence is as follows: the filling soil is transported out of the designated position of the field area to be stored for later-stage backfilling, the elevation of the field area is taken to be the same elevation, then the surface collapsible loess is tamped and reinforced by adopting a dynamic compaction method, and after the foundation reinforcement treatment is finished, the construction of the engineering pile is carried out; the construction direction is as follows: adopting propulsion construction and symmetrical construction from the center to two sides;

fourthly, construction of the bored pile, namely, adopting a rotary drilling and expanding machine as construction machinery, firstly calibrating the pile position, drilling by the rotary drilling and expanding machine, then hoisting a reinforcement cage in a pile hole, placing a pouring guide pipe, and performing concrete pouring and pile forming;

and fifthly, constructing lime-soil compaction piles, wherein the lime-soil compaction piles are constructed at the position of the building foundation, the diameter of each pile is 400mm, the length of each pile is 7-15.9 m, and the distance between every two adjacent piles is 1000 mm.

2. The pile foundation construction method according to claim 1, characterized in that: in the second step, the division of the construction area further comprises the division of labor organization and work content: according to the scale of the construction engineering of the engineering station house and the division of the construction areas, each area operation team carries out plane flow line operation; and according to the engineering quantity and the size of the working face at different construction stages, the labor force is effectively arranged to enter and exit the field, so that the labor force resource is fully utilized.

3. The pile foundation construction method according to claim 1, characterized in that: in the fourth step, the construction of the cast-in-situ bored pile comprises the following steps:

(1) pile position lofting, namely adopting a principle from whole to local, adopting a total station instrument to perform accurate lofting of a pile foundation position, and timely rechecking the lofted elevation;

(2) the pile driver is in place, and when the pile driver is in place, the pile driver is aligned with the pile position, so that the vertical stability is ensured, and the inclination and the movement are avoided in the construction process;

(3) the method comprises the steps of forming holes on a pile foundation, starting drilling operation, wherein the drilling operation is carried out slowly and quickly, the footage is 40-50cm each time, determining whether an underground unfavorable stratum exists, if the drilling operation is normal after the footage is 5 m, the footage can be properly increased, the footage is controlled to be 70-90cm each time, after the drilling operation is carried out to a preset depth, idle rotation soil removal is carried out at the hole bottom, then the rotation is stopped, and a drill rod is pulled out of a drilled hole;

(4) manufacturing and installing a reinforcement cage, wherein the reinforcement cage is manufactured according to a design drawing, when the reinforcement cage is installed, the reinforcement cage is slowly moved, the reinforcement cage is hung above a hole site, the reinforcement cage is aligned with the hole site, stabilized and slowly lowered, the center of the reinforcement cage is consistent with the center of a drilled hole by depending on the self weight of a pulley of a first hanging point and the weight of the reinforcement cage, after the reinforcement cage is placed, a cross line is hung on a symmetrical reinforcement of the reinforcement cage, a single pile guard pile is connected, the cross line is pulled, whether two cross points are overlapped or not is checked by using a hanging plumb, and when the requirement is not met, a reinforcement cage hanging rib is adjusted to be overlapped;

(5) placing a guide pipe, calculating the required length of the guide pipe according to the top elevation and the bottom elevation of a protective cylinder and considering the height of a skid, trial-splicing the guide pipe, wherein the guide pipe is installed manually by adopting a crane in a matched mode, the guide pipe is placed in a manner that the guide pipe is positioned at the center of a steel reinforcement cage in an eye-looking and manual-matched mode, then the guide pipe is stably sunk and prevented from clamping a steel reinforcement framework and colliding with the wall of a hole, the guide pipe is firstly placed to the bottom of the hole by using the crane during installation, then the guide pipe is lifted by 40cm, the bottom of the guide pipe is 40cm away from the bottom of the hole, after the height of the guide pipe is determined;

(6) pouring concrete, wherein the concrete is poured by adopting a hopper after being transported to the site by a tank truck;

(7) and detecting the engineering pile, and detecting the bearing capacity and the integrity of the pile body of the single pile after the concrete strength of the pile body of the test pile reaches the design requirement.

4. The pile foundation construction method according to claim 1, characterized in that: in the fourth step, during pile group foundation construction, when holes are formed in adjacent piles beside concrete just after pouring, the safety distance of the pile is larger than 4 times of the pile diameter or the minimum time interval is not less than 36 hours, and when row-by-row piling is carried out, the propelling direction of piling is changed row-by-row.

5. A pile foundation construction method according to claim 3, characterized in that: engineering pile detects including low strain wave speed method, sound wave transmission detects and the test of static load detects, adopt sound wave transmission method and low strain wave speed method to jointly detect pile shaft quality, detect quantity is 30% of total pile number, wherein, sound wave transmission detects and is no less than 10% of total pile number, every stake all sets up 2 ultrasonic detection pipes, steel pipe internal diameter 57mm, wall thickness 3mm, according to sound wave projection method testing result, engineering pile who has a problem to pile foundation ultrasonic detection adopts the core drilling method to detect, the test of static load detects the spot check quantity and is not less than 1% of total pile number, and is no less than 3.

6. The pile foundation construction method according to claim 1, characterized in that: in the fifth step, the construction of the lime-soil compaction pile comprises the following steps:

(1) and the construction sequence

According to relevant regulations and technical requirements, the construction sequence of the lime-soil compaction piles is that the construction is carried out by adopting a jump driving method of firstly arranging the lime-soil compaction piles in the inner row and then arranging the lime-soil compaction piles in the outer row and then arranging the lime-soil compaction piles at intervals;

(2) setting position for paying off

According to a control axis, a pile arranging control line is led to the periphery of a foundation pit, then the center position of a pile is released according to a construction drawing, a wooden wedge or a lime point is used for marking, the deviation of the pile position is controlled within 0.4D, D is the diameter of a pile hole, a measurer needs to check in time, a hole can be formed according to the released pile point after accuracy is correct, in order to ensure the accuracy of paying off, the control line is arranged in the daytime as much as possible, so that the problem of paying off at night is avoided, and the quality problem is caused when the control line is not in time;

(3) forming a hole

The lime-soil compaction pile is constructed by adopting a long spiral drilling method, after a drilling machine is in place, a drill bit is aligned to the central position of the placed pile, the verticality of a drill rod is corrected from two different directions by using a plumb bob, after the standard allowable range is determined, the drill rod is driven into the soil by using a D400 diesel hammer, the drilling depth is marked on the drilling machine from the upward amount of a pile tip 1/2 to the designed elevation position by using red paint, the hole is formed by lifting, when the water content is more than 20%, the hole shrinkage phenomenon is easy to occur, the hole forming construction cannot be carried out, tamping and filling are carried out in time after the hole forming, and the situation that the drilling machine rolls to avoid the upper shrinkage hole as much as possible, if the shrinkage hole is caused by rolling, secondary hole forming is carried. After the hole is formed, the loose earth on the ground surface is poked from the center of the hole to the periphery so as to avoid falling into the pile hole to influence the pile forming quality;

(4) mixing with lime soil

Firstly, sieving soil and slaked lime respectively, tamping and filling the mixed lime soil in time, wherein the lime soil cannot be used every other day, and measuring the ash content and the water content of the lime soil before construction every day to ensure that the ash content and the water content of the mixed lime soil meet the requirements;

(5) tamping, tamping

Before filling the pile hole, tamping the bottom of the hole by 3-4 hammers, then backfilling and tamping the pile by layers by using lime soil under the state of the optimal water content, wherein the thickness of the filler is 400-500 mm each time, the filler is symmetrically blanked from two directions respectively, the phenomenon that a pile body is askew due to uneven filler is avoided, the lifting height of the tamping hammer is not less than 3m, the tamping frequency is not less than 6 times, the filler can be filled after being tamped and expanded, the steps are repeated until the designed elevation is reached, the average compaction coefficient of the filler is not less than 0.97, the minimum value of the compaction coefficient is not less than 0.93, and the bottom of the hole must be tamped before filling;

(6) and detecting the pile body compactness according to the required frequency. Randomly sampling and detecting the average compaction coefficient of the lime soil or soil filler within the range of the length of the tamped pile, wherein the number of sampling detections is not less than 1 percent of the total number of the pile and not less than 9, the average compaction coefficient of the soil between the piles within the depth of processing is sampled and detected, the number of detection exploratory wells is not less than 0.3 percent of the total number of the piles, each monomer engineering is not less than 3, the bearing capacity detection is carried out 14d-28d after the pile is formed, the number of detections is not less than 1 percent of the total number of the piles, and the static load test of the composite foundation of each monomer engineering is not less than 3 points;

(7) and after the whole construction is finished, the bearing capacity, the compaction effect and the like are detected to meet the design requirements.

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