CN-120331237-A - Construction method of pile foundation with super-thick water-permeable sand layer

CN120331237ACN 120331237 ACN120331237 ACN 120331237ACN-120331237-A

Abstract

The invention discloses a construction method of an ultra-thick water-permeable sand layer pile foundation, which comprises the following steps of preparing a site, a platform and a slurry pond, cleaning the site, setting a construction platform and preparing the slurry pond, burying a pile casing, burying a steel pile casing with proper height according to geological conditions, burying a drilling machine in place, checking the pile position to ensure stable positioning of the drilling machine, preparing mud by selecting proper clay, and enabling the performance index of the mud to meet the requirements. The device solves the problems of sand prevention failure and unreliable anchoring in the traditional process, is suitable for adjacent water super-thick permeable sand layers, and has the advantages of high efficiency, environmental protection, safety and the like.

Inventors

REN JIE
YANG LE
ZHU YALIN
WANG KAI
YANG FA
WANG YIXIAN
ZHU PINGYANG
SHI JUNJIE
YAO QIHAI
ZHANG HANG
QIAN CHENG

Assignees

ANHUI CONSTRUCTION INVEST GROUP CO LTD
UNIV HEFEI TECHNOLOGY

Dates

Publication Date: 20250718
Application Date: 20250526
Priority Date: 20250526

Claims (10)

1. The construction method of the super-thick water-permeable sand layer pile foundation is characterized by comprising the following steps of: step 1, preparing a site, a platform and a mud pit, cleaning the site, setting a construction platform and preparing the mud pit; step 2, embedding a pile casing, namely embedding a steel pile casing with a proper height according to geological conditions; step 3, positioning the drilling machine, namely rechecking the pile position, and ensuring the stability and positioning of the drilling machine; step 4, preparing slurry, namely selecting proper clay to prepare slurry, so that the performance index of the slurry meets the requirement; step 5, drilling to form holes, namely drilling by adopting proper drilling speed and parameters, and timely sampling to judge soil layer change; step6, final hole inspection, namely using a hole forming detector to inspect the hole depth and the hole diameter; step 7, installing the supporting device, namely after combining the supporting device body and the supporting brace system, hanging the supporting device body to a designated position through a position limiting hanging rope system, and anchoring the supporting device body on the hole wall by utilizing an automatic spring-open anchoring device; step 8, hole cleaning, namely performing hole cleaning twice to ensure that the thickness of sediment at the bottom of the hole meets the design requirement; Step 9, placing a reinforcement cage and a guide pipe; step 10, pouring concrete, namely continuously pouring the concrete to a designed elevation to ensure pile forming quality; and step 11, pile head chiseling and pile foundation detection, namely, pile head chiseling is carried out after the foundation pit is excavated, and pile foundation quality detection is carried out.
2. The construction method of ultra-thick water-permeable sand layer pile foundation according to claim 1, wherein the step 1 is specifically that the center position of the pile is lofted by using a total station coordinate lofting method, the center of the pile is determined, cross pile protectors are set around the center which is used as the center and is larger than the radius of the pile body, marks are made and fixed, the measurement error is zero, and the pile is used Reinforcing steel bars with the length of 35-40 cm are driven into the ground for 30cm to serve as the center point of the pile, cement mortar or concrete is filled around the pile for protection, and marks are made around the pile position.
3. The construction method of the ultra-thick water-permeable sand layer pile foundation according to claim 1, wherein the construction method is characterized in that in the step 2, a steel pile casing with the height of 3m is adopted in construction according to geological conditions, the diameter of the pile casing is 1.8m, the wall thickness is 6mm, the bottom and the periphery of the pile casing are filled with clay and tamped in layers, the embedded depth of the pile casing is 2.7m, the top of the pile casing is 0.3m higher than the maximum wave height of the water surface, steel bar lifting lugs are welded at the top, the vertical line of the center of the pile casing is overlapped with the central line of the pile, the plane allowable error is 50mm, the vertical inclination rate is less than or equal to 1%, and whether the pile casing is deviated or sunk is checked in the drilling process and is processed in time according to the checking result.
4. The construction method of the ultra-thick water-permeable sand layer pile foundation according to claim 1, wherein the step 3 is specifically that the pile position is rechecked before the drilling machine is in place, the ground where the drilling machine is in place is compacted or replaced by a road roller, the center of a drill bit and the lofting point of the pile center are located on the same plumb line after the drilling machine is in place, the pile position is correct when hole forming is ensured, and the drilling machine is stable in construction.
5. The construction method of the ultra-thick water-permeable sand layer pile foundation according to claim 1 is characterized in that step 4 is specifically that clay with fast hydration, strong slurry making capability and high viscosity is prepared, various indexes of the clay are determined through experiments, the technical indexes of the clay are measured frequently in the drilling process, the relative density of the slurry is adjusted at any time according to engineering drilling requirements, various indexes are kept to meet requirements, and the progress is not influenced by the over-concentration of the slurry, and the collapse of holes is not caused by over-dilution.
6. The method for constructing a pile foundation with an ultra-thick water-permeable sand layer according to claim 1, wherein the step 5 specifically comprises the following steps: Step 5.1, controlling the drilling speed, namely, firstly, slowly drilling the bottom of the pile casing at a low speed to ensure that a firm mud skin wall is arranged at the bottom of the foot, if the soil at the bottom of the pile casing is soft and leakage occurs, lifting the drill bit, pouring clay blocks into the hole, then putting the drill bit into the hole for reversing, extruding the clay into the hole wall to block the leakage gap, and continuing drilling after stabilizing the mud, and then, normally drilling at an increased speed after the drill bit passes through 2.0m of the bottom of the pile casing, wherein the lifting speed of the drill bucket is controlled to be 0.75-0.80m/s; Step 5.2, geological sampling, namely, when the drilling process encounters soil layer change, a slag sample is fished at the soil layer change position to identify a soil layer, the soil layer is recorded into a record table, the soil layer is checked with a geological profile, and a colleague tests a drilling hole to measure the specific gravity, viscosity and sand rate of mud; And 5.3, hole forming, namely testing hole forming before test pile drilling, performing construction according to actual site distribution during formal construction test pile, timely adjusting drilling parameters when encountering different geology by operating a drilling machine, strictly controlling drilling speed when drilling, enabling the drilling speed to be suitable for feeding slurry and discharging slag, enabling the drilling speed to be lower than the slurry feeding and discharging slag speed, stopping drilling when a drill rod is added, lifting the drilling tool away from the bottom of the hole, recycling slurry for a few minutes, stopping pumping, adding the drill rod, continuously completing hole forming construction once, performing preliminary hole cleaning after the hole forming reaches the designed hole depth, further checking and accepting, and performing the next procedure after the drilling speed is qualified.
7. The construction method of the ultra-thick water-permeable sand layer pile foundation according to claim 1 is characterized in that step 6 is specifically that after drilling reaches a designed elevation hole site, a hole-forming detector is used for checking hole depth, hole diameter, hole site and hole shape, perpendicularity and geological conditions of a hole bottom, then a final hole record is filled, a supervision engineer is timely informed to go to on-site checking and accepting, the next procedure is carried out after qualified, when the rotary drilling approaches to the final hole, a bottom-sealing sand-fishing drill bit is used for drilling, thick mud at the hole bottom is drawn out, and when the depth reaches to the final hole, the drilling is stopped for 20-30 min, suspended matters in the mud are precipitated, and the drill bit is used for fishing out.
8. The method for constructing the pile foundation with the ultra-thick water-permeable sand layer according to claim 1, wherein the step 8 adopts a method for removing sediment at the bottom of the hole twice, and specifically comprises the following steps: 8.1, lifting the drill bit 150-200 mm away from the bottom of the hole after drilling reaches the designed hole depth, and starting a slurry pump to clean the hole in a positive circulation way for not less than 20min; Step 8.2, checking and accepting pile holes, namely after pile holes are finished, self-checking according to design requirements, checking and accepting various indexes of depth of the finished holes, sediment and slurry performance, and after the checking and accepting are qualified, performing on-site meter filling and visa work; 8.3, placing a reinforcement cage after the pile hole is accepted, performing positive circulation by using the guide pipe after the reinforcement cage and the pouring guide pipe are placed, wherein after the hole is required to be cleaned, the sediment at the bottom of the hole is not more than 100mm, the time interval from the hole cleaning to concrete pouring is not more than 30min, if the time interval is more than 30min, and the concrete pouring can be performed after the hole is required to be cleaned again; 8.4, after the pouring is finished, the speed of the lifting guide pipe is required to meet the following conditions that the concrete surface opening is gradually closed, no slurry is mixed, and no mud mixing core exists; 8.5, pouring each pile, namely, twice slump measurement, firstly sampling and manufacturing test blocks, wherein each pile is not less than 3 blocks, numbering and marking the sampling time, recording in a concrete pouring record, demoulding after 24 hours of manufacturing the test blocks, placing the test blocks in a standard curing room for curing for 28 days, carrying out a test on time, and archiving and checking the test results; 8.6, determining the elevation of the pile casing by using a level gauge before drilling, calculating the hole depth according to the elevation of the bottom of the hole required by design by taking the elevation as a base point, determining the hole depth by using the length of a drilling tool, wherein the deviation of the hole depth is not shorter than the design depth, the over-drilling depth is not more than 20cm, checking the hole depth, the aperture, the hole site, the hole shape and the thickness of sediment at the bottom of the hole when the drilling depth reaches the design requirement, and adopting a cage type hole detector for checking if the hole shrinkage phenomenon occurs.
9. The method for constructing a pile foundation with an ultra-thick water-permeable sand layer according to claim 1, wherein the step 9 specifically comprises: Step 9.1, threading is carried out by adopting a straight thread threading machine before the mechanical sleeve connection of the main reinforcement of the steel reinforcement cage, threading detection is carried out by using a ring go gauge and a ring no-go gauge, and the next procedure is carried out after the detection is qualified, wherein one locating rib is arranged every 2m when the reinforcing rib is installed, a group of locating ribs is arranged every 2m, and 4 locating ribs are uniformly arranged around the pile foundation reinforcing ribs; 9.2, transporting to a working point by adopting a flat car, setting 2 lifting points by adopting a crane, and lifting by using a method of lifting and sinking section by section; Step 9.3, the placed reinforcement cage is temporarily fixed by using a steel pipe or a section steel through a stiffening stirrup thereof, the upper reinforcement cage is temporarily suspended by a crane to form a suspension state, the upper and lower sections are centered to form a straight line, the position of the main reinforcement is aligned, the verticality is controlled by using a pendant from front to back, left to right, and mechanical sleeve connection is carried out after adjustment is completed; 9.4, when the two sections of reinforcement cages are connected, the axes of main reinforcement bars of the reinforcement cages of the upper section and the lower section are aligned and connected by adopting a mechanical sleeve, after the upper section and the lower section are connected in a butt joint mode, the steel pipe or the section steel for supporting is pulled out, and the reinforcement cages are continuously sunk; 9.5, calculating and determining the length and the welding position according to the elevation position of the control platform, wherein the overlap joint length and the welding seam of the lifting ring steel bars adopt standard welding seams; And 9.6, placing a guide pipe, namely, the upper end of the sound measuring pipe is 30cm higher than the pile top surface, the lower end of the sound measuring pipe is suspended for 10cm, each section of the sound measuring pipe corresponds to the section of the reinforcement cage, the sections of the sound measuring pipe are connected through sleeves, the length of each sleeve is 80cm, the outer diameter of each detection pipe is 57mm, the diameter of each sleeve is 60mm, the sound measuring pipe is bound on a stiffening reinforcement, the bottom end of each sound measuring pipe is firmly welded with a steel plate to form a back cover, water is filled into the pipe before concrete is poured, the sound measuring pipe is blocked by a plug, 3 detection pipes are arranged when the pile diameter is smaller than 1.5m, and 4 detection pipes are arranged when the pile diameter is larger than or equal to 1.5 m.
10. The method for constructing a pile foundation with an ultra-thick water-permeable sand layer according to claim 1, wherein the step 10 is specifically: 10.1, after the pouring is started, the continuous pouring of the concrete of the same pile is required to be carried out continuously, and the continuous pouring time of the concrete of the same pile is not longer than the initial setting time of the concrete; Step 10.2, preventing concrete mixture from overflowing from the top of the hopper or falling into the bottom of the hole from outside the hopper in the pouring process, observing the descending condition of the concrete in the pipe and the ascending and descending condition of the water level in the hole, and Measuring the height of the concrete surface in the hole; And 10.3, in the pouring process, when the concrete in the guide pipe is not full and contains air, the subsequent concrete is poured in slowly, so that the high-pressure air bag is prevented from being formed in the guide pipe.

Description

Construction method of pile foundation with super-thick water-permeable sand layer Technical Field The invention relates to the technical field of bridge construction, in particular to a construction method of an ultra-thick water-permeable sand layer pile foundation. Background Bridge pile foundations are important components of bridge engineering, and common foundation forms include flat plates, piles, combined forms and the like. The dimensions and depth should be determined according to the loading and geological conditions of the superstructure while considering workability of construction. The arrangement of pile foundations is optimized according to the load distribution and geological conditions of the bridge so as to fully utilize the bearing capacity of stratum and reduce the settlement and displacement of the pile foundations. Bridge pile foundation construction is one of the key links of the whole engineering. The pore-forming method should be selected according to geological conditions and construction conditions, such as mechanical pore-forming, manual pore-forming, punching, etc. The pouring technology should consider the factors of the mixing proportion of the concrete, the pouring speed, the conduit burial depth and the like so as to ensure the quality of the concrete and the integrity of the pile foundation. In the construction process, effective quality control measures such as periodic quality detection, construction parameter control and the like are adopted to ensure that the construction quality of the pile foundation meets the requirements. In the bridge pile foundation construction process, special conditions such as emergencies, underground barriers, ultra-thick water permeable sand layers, adjacent water construction, high bearing layers and the like can be met. For these cases, corresponding treatment measures should be taken to ensure smooth progress and quality safety of the construction. Disclosure of Invention The invention aims to solve the defects in the prior art, and provides a construction method of an ultra-thick water-permeable sand layer pile foundation, so as to solve the problems in the background art. In order to achieve the above purpose, the present invention provides the following technical solutions: A construction method of an ultra-thick water-permeable sand layer pile foundation comprises the following steps: step 1, preparing a site, a platform and a mud pit, cleaning the site, setting a construction platform and preparing the mud pit; step 2, embedding a pile casing, namely embedding a steel pile casing with a proper height according to geological conditions; step 3, positioning the drilling machine, namely rechecking the pile position, and ensuring the stability and positioning of the drilling machine; step 4, preparing slurry, namely selecting proper clay to prepare slurry, so that the performance index of the slurry meets the requirement; step 5, drilling to form holes, namely drilling by adopting proper drilling speed and parameters, and timely sampling to judge soil layer change; step6, final hole inspection, namely using a hole forming detector to inspect the hole depth and the hole diameter; step 7, installing the supporting device, namely after combining the supporting device body and the supporting brace system, hanging the supporting device body to a designated position through a position limiting hanging rope system, and anchoring the supporting device body on the hole wall by utilizing an automatic spring-open anchoring device; step 8, hole cleaning, namely performing hole cleaning twice to ensure that the thickness of sediment at the bottom of the hole meets the design requirement; Step 9, placing a reinforcement cage and a guide pipe; step 10, pouring concrete, namely continuously pouring the concrete to a designed elevation to ensure pile forming quality; and step 11, pile head chiseling and pile foundation detection, namely, pile head chiseling is carried out after the foundation pit is excavated, and pile foundation quality detection is carried out. The invention adopts the further technical scheme that the step 1 comprises the steps of carrying out center position lofting of piles by using a total station coordinate lofting method, determining the center of pile positions, setting cross pile protection around the pile body with the center as the center of a circle and with the radius larger than the radius of the pile body, marking and fixing, wherein the measurement error is zero error, and the pile positions are usedReinforcing steel bars with the length of 35-40 cm are driven into the ground for 30cm to serve as the center point of the pile, cement mortar or concrete is filled around the pile for protection, and marks are made around the pile position. According to geological conditions, a steel pile casing with the height of 3m is adopted during construction, the diameter of the pile casing is 1.8m, the wall thickness is 6mm, clay is