After the pile foundation construction is completed and the pile heads are cut, what is the next step?

After the pile foundation construction is completed and the pile heads are cut, what is the next step?

Test the bearing capacity of the shaft piles, and proceed to the next step of foundation construction after passing the test. How long after the first pile foundation can be completed for subsequent pile foundation construction

This depends on the supervisor. If the supervisor and the owner agree with the entire construction process of your first pile, they feel that the construction can be completed according to your previous plan. Guarantee that they will allow you to carry out subsequent pile foundation construction.

Because this first-article system is not a mandatory requirement in national regulations. The first-article system is just a management method proposed by the owner or supervisor for quality management, so you need to study how this system is stipulated. . If you are required to prepare a relevant summary report after completing the first piece and submit it to the supervisor or owner for approval, then you must collect the information and information on the first piece and complete the summary and submit it for approval before subsequent construction can begin. Who should construct the broken pile heads? The general contractor or the pile foundation construction unit

Normally, the broken pile heads are subcontracted, and it has nothing to do with the pile foundation construction team, because the pile heads need to be installed, and the pile foundation construction team does not have them. Therefore, general contracts will not reflect how to carry out safe production in pile foundation construction. 1. Strengthening construction safety management (1) The person in charge of the project construction unit (project manager department) must be fully responsible for the safe production work of the project construction and make it clear that he is responsible for safe production. The first responsible person is responsible for establishing a safety management organization, implementing a safety production responsibility system, determining the job safety responsibilities of leading cadres, managers and employees, and organizing the formulation and implementation of safety measures and rules and regulations that are consistent with on-site production. We must conscientiously implement the policy of "safety first, prevention first" and implement the safety rules and regulations of the national and local industry authorities. (2) The construction unit must set up a production safety leadership group with full-time (part-time) safety officers to assist leaders in implementing safety rules and regulations, organize and carry out safety activities, insist on inspection and guidance of production safety at the job site, and solve problems in production safety, Discourage illegal commands and stop illegal operations. They are also responsible for educating and training new workers and temporary workers on on-site safety knowledge and safe operation skills, writing safety production technology designs and measures for construction projects, and conscientiously doing daily safety management work. (3) The construction unit must establish a safety inspection and safety education system, and insist on conducting safety production inspections and safety education and training in accordance with regulations. Before the start of the project, the safety production conditions of the work site must be inspected and submitted to the competent department for review and approval before construction can start. During the construction period, inspections should be conducted once a month; the machine should be inspected once a week, and any problems and accidents found should be reviewed. For hidden dangers, measures must be formulated, implemented by people, and rectified within a time limit. (4) The team must adhere to the shift handover system. The team leader should assign work tasks and explain safety precautions before the shift. They should summarize after the shift and criticize violations. When handing over the shift, the operators should inspect the machinery they use. Devices and tools should be inspected in detail, and if any unsafe factors are found, they should be dealt with and reported in a timely manner. (5) On-site workers must receive safety management, safety education and safety skills training. Special types of work, such as electricians, welders, crane workers, blasters and motor vehicle drivers, etc., must undergo strict training and assessment and must hold certificates to work. Operation. (6) Operators should strictly abide by labor disciplines and safety regulations at work. They should not fight, leave their jobs without permission, and should not drink alcohol before going to work. They should wear labor protection supplies, work clothes, and safety helmets. They are not allowed to wear slippers. Safety belts must be worn when working on the tower. (7) Clear and eye-catching safety responsibility signs and safety discipline (or safety management regulations) placards should be hung at the construction site, and safety warning signs should also be hung at dangerous locations. (8) Operators must obey instructions when multiple people are working together. They have the right to refuse to accept illegal and risky instructions, and have the right and obligation to promptly report and deal with dangerous situations and carry out accident rescue. (9) Accidents must be reported step by step in accordance with regulations, organize investigation and handling, identify the cause of the accident, and take serious measures to prevent similar accidents from happening.

2. Carefully make safety arrangements for the pile foundation construction site (1) Before entering the construction site, you must conduct a survey of the construction site to clarify the high-voltage lines, underground pipes, communication cables and other structures on the site ; The construction site should have the construction conditions of "three connections and one leveling", and the construction site should have sewage pits, sewage pools and other facilities to achieve civilized production. (2) Safety signs should be set up at the construction site, and safety warning signs should be installed at dangerous locations; power supply lines within the construction site should be elevated or buried in trenches, and the insulation condition of electrical lines should meet safety requirements; adequate lighting should be provided for nighttime production.

3. Strengthen the safety and protection of pile foundation construction equipment (1) The drilling frame and platform must be installed smoothly, squarely and firmly, and the parts must be complete; open gears, belt drives and accurate rotating shafts Each head should be equipped with protective railings or protective covers. (2) The wooden track of the abutment must be stable and of appropriate length; the platform board must be non-slip and firm; the tower ladder, workbench, and railings must be installed firmly and reliably; the upper part of the drilling frame must have a workbench that is convenient for high-altitude operations; the water drilling platform must be It should be sturdy and secure and not affected by water flow. (3) The distance between the top of the drill frame and the high-voltage power supply line complies with safety regulations or meets safety requirements; the distribution box must be equipped with leakage protectors and other safety facilities, there are rainproof measures outside the cabinet, and the outer shell of the electrical device is equipped with protective grounding or zero connection. ; Electrical switches must be intact, fuses, fuses, etc. are used according to regulations. They are not allowed to exceed the rated standards or be replaced with copper wire or iron wire. (4) Dangerous parts of the construction site should be equipped with corresponding safety protection facilities; and sufficient fire prevention facilities should be equipped. (5) The wire rope and rope clamp used for lifting must be safe and reliable.

4. Strict safety operations in pile foundation construction (1) Each shift should inspect the bolts of the platform, drilling frame, lifting system, mechanical devices and other parts. (2) When the drilling frame and platform are moved, no people or untied floating objects are allowed on the tower and platform; when using the SPJ-300 trailer drill or truck-mounted drilling rig to move, the tower should be placed first and then moved; There should be unified command when installing and dismantling the platform and drilling rig. (3) When working at high altitude, all tools and items must be put into tool bags to prevent items from falling; no work is allowed on or below the tower at the same time, and tools and items are not allowed to be thrown. (4) When the universal shaft of the drilling rig rotates, personnel are not allowed to cross or stand on the turntable; when lifting the drill bit, the wellhead personnel must stand outside the dumping range of the drilling tool; when lifting the puller, the rotation of the vertical shaft must be stopped and someone should be supervised switch. (5) When the machine is running, it is not allowed to disassemble and repair parts, nor to scrub; it is not allowed to wear gloves to pick up, hang or wax the belt; it is not allowed to use iron tools to pull the belt; it is not allowed to pull, touch or step on the running wire rope. . (6) Before lowering the steel cage, clear the obstacles around the opening; when lowering the steel cage, people are prohibited from climbing on the steel cage to add weight; when lifting the steel cage or conduit, a steel wire rope with a diameter greater than 10mm must be used. Wire ropes exceeding the specified wear degree should be replace. (7) Fire, smoking, and cigarette butts are not allowed around acetylene bottles and oxygen bottles; when welding steel cages on the construction site, the safety operating procedures for electric and gas welding must be strictly followed. (8) Dump trucks can only be used on construction sites and are not allowed to be driven on highways, used as a means of transportation, or carry people. How to carry out pile foundation construction on blown soil foundation

If you only have one drilling rig, you can only form one pile foundation construction team. This team must have a captain who understands construction technology, and then there must be welders, crane workers, and small workers, and these people must have valid employment certificates. Such a team can only work on an affiliated basis. Only when you have sufficient funds can you set up a company and fly on your own. What are the information on the pile foundation construction process?

I don’t know what type of pile foundation you are talking about. Search it on Baidu Wenku!

For bored piles, please refer to: wenku.baidu./view/3b454f52f01dc281e53af0a5. Is the second underground foundation to be grooved first or pile foundation construction to be carried out first?

The above two situations are actually It can be operated during construction. Whether to construct the pile foundation first or excavate the foundation pit first depends on the situation. In most cases piling is driven first.

Advantages of constructing pile foundation first:

1. Facilitate construction schedule arrangement.

Because most pile foundation construction requires a certain maintenance period. After the pile foundation construction is completed, foundation pit excavation can be carried out without special time waiting for strength maintenance on the pile foundation (except for high-strength prefabricated piles, but there is also time for pore water pressure to dissipate).

2 The advantages of surface construction are that it is conducive to device deployment, conducive to sewage discharge (such as bored piles), ample working surface, and high safety. There is a hard shell layer on the ground surface, which can generally be installed directly and can be constructed without or with little foundation treatment.

The advantage of excavating the foundation pit first is that it can save part of the pile delivery costs (prefabricated piles) and hole forming costs. However, in order to drive piles, sufficient working surface must be left during excavation of the foundation pit, thereby increasing the earthwork workload and increasing earthwork costs.

Generally speaking, under normal circumstances, piles are driven first and then the foundation pit is excavated. When there is no groundwater drainage within the excavation range of the foundation pit, the ground at the bottom of the foundation pit is hard and does not need to be treated, and piling can be installed, and the soil conditions on the side walls of the foundation pit are good and only sloping excavation is required without special support, you can consider excavation first. Dig a foundation pit. As a special case, when manually digging piles, the foundation pit is generally excavated first and then the piles are driven. What to do if a cave is encountered during pile foundation construction

Even if it is reported, the supervisor, supervision director, director, design representative, and owner representative must be notified. After all, the responsibility does not belong to the construction unit, but to the design unit when it is outside. If there is an oversight, just ask the design unit to redesign it

If the problem is not serious and you don’t want to delay the construction period (redesigning will take at least several months), then just keep pouring concrete in until it is blocked. But if there are problems in the future, the construction unit will be responsible, especially for end-bearing piles. What are the key points in pile foundation construction?

pKey points of pile foundation construction:

1. The most common points of quality control of several common engineering piles:

1. Pre-control stage

1). Prepare supervision plans and implementation details according to different projects.

2) Do a good job in self-review and joint review of drawings. This work is very important and should not be underestimated. For example: the foundation of a certain project uses punched (drilled) hole mud wall retaining cast-in-place piles. During the self-review of the drawings, our supervisor found that the slenderness ratio of the piles could not meet the specification requirements. At this time, we should promptly contact the designer Get in touch and make timely corrections.

3) Audit the construction organization design and pile foundation construction plan submitted by the construction unit; the "Geological Survey Report" is the main basis for the construction of pile foundation projects, so it should also be read carefully and the geological profile map Have a clear impression.

4) The personnel and organizational structure of the on-site project supervision department must be reasonably configured, and measuring and testing instruments and reference books must be in place.

5) Check whether the three connections and one leveling meet the construction requirements. The original topography, landform, elevation, etc. of the construction site should be carefully reviewed. Overhead lines (high-voltage lines) and underground obstacles must be dealt with. The site should be level, drainage should be smooth, and the ground bearing capacity required for pile driving should be met; check whether the pile foundation construction is correct. Adverse effects on surrounding buildings.

6) Audit the construction equipment inspection form: Understand and check the technical performance data and relevant parameters of the construction machinery and its supporting equipment. The pile-forming machinery must be certified and qualified, and unqualified machinery shall not be used.

7) Review of materials submitted for inspection: Before the start of construction, the building materials submitted for inspection by the construction unit should be inspected according to the requirements of the specifications, and approved for use after meeting the requirements.

8) Assist the owner to conduct trial piling work before the formal construction of the pile foundation site. The purpose is twofold: first, to check whether the construction capability meets the requirements; second, to extract and determine the relevant technical parameters of the pile. It is necessary to keep good records of pile testing and prevent the pile testing work from being a formality.

2. In-process control stage:

1) Review the pile foundation axis. After it is correct, review the pile position. The allowable deviation for pile position setting out is: pile group ≤20mm, single pile ≤10mm, the review of axis and pile position measurement and setting out is an important task in pile foundation construction supervision. The "Measurement Inspection Form" submitted by the construction unit should be carefully audited.

2) Before concealing the steel cage, on-site supervisors should conduct concealment project acceptance and check whether the specifications, varieties, sizes, stirrup spacing, density area length, welding quality and welding rod specifications of the steel cage are satisfactory. Comply with design and specification requirements and be controlled as a stopping point. The construction unit should make a record of concealed acceptance of steel bars. The records should reflect the specifications, varieties, quantities, stirrup spacing, steel cage length and other main contents of the steel bars.

3). Strictly control the concrete strength grade and construction mix ratio according to the design requirements; supervise the entire process of concrete test block production at a side station and track and submit it for inspection; the construction site should be equipped with a slump cylinder for parallel inspection The slump of concrete.

2. Key points for quality supervision of punched (drilled) hole mud retaining cast-in-place piles:

1. Prior control stage:

1). The on-site supervision department should Equipped with calibrated measuring ropes, mud hydrometers, viscometers and other testing tools, the construction site should also be equipped with hole detectors.

2) When testing piles, attention should be paid to the determination of pile length. If it is an end-bearing pile, attention should also be paid to the depth and interface of the bearing layer.

2. In-process control stage:

1) Check the pile diameter and effective length of the pile: measure the maximum diameter of the drill bit or punch, and deal with the pile before punching (drilling) the hole. Check the position setting out and pile driver leveling. Check the specific gravity and viscosity of the mud at any time during the drilling process. The mud level should be more than 1.0m higher than the groundwater level. When affected by water level fluctuations, the mud level should be 1.0m higher than the highest water level. More than 5m; when entering different interfaces and the on-site geological conditions are inconsistent with the "geological survey report", geological survey personnel must be asked to identify. Especially when entering the interface of the bearing layer, slag sampling must be carried out. Supervisors should carefully identify and confirm so that Determine the thickness of the entering bearing layer. After the final hole, use a measuring rope to measure the depth of the pile hole and the thickness of the sediment. The depth of the measuring hole should be used as a stopping point to control;

2) If the diameter of the steel cage is small, it should also be noted that the stiffening hoop should be placed at Outside the main reinforcement, so as not to hinder the work of the conduit (the inner diameter of the steel cage should be more than 100mm larger than the conduit joint), the steel cage can be hoisted after the initial cleaning and measuring the hole depth. Supervisors should stand by to supervise the entire process, especially the welds must be completely Check that the center lines of the longitudinal steel bars for lap welding must be on the same axis, the steel cage concealment acceptance has passed, and secondary hole cleaning has been completed. Underwater concrete should be poured within four hours after the sediment thickness meets the allowable deviation of the design and specifications.

3) When issuing the underwater concrete opening appraisal, special attention should be paid to checking whether the strength grade of the underwater concrete is consistent with the design, whether the slump meets the construction requirements (generally 180-220mm), and Control the amount of cement according to the concrete strength and mix ratio required by the design. At the same time, the supervisor should supervise the construction unit to make a set of test blocks for each pile. If the irrigation volume is greater than 50m3, a set of test blocks should be made for every 50m3.

4) When pouring concrete underwater, the distance from the bottom of the conduit to the bottom of the hole should be 300-500mm. At the same time, check whether the assembly of the conduit is tight. Once water intrusion is discovered, work must be reworked immediately. Supervisors should Calculate the capacity of the funnel and conduit before pouring concrete, and ensure that the initial pouring volume ensures that the conduit is buried more than 0.8m below the concrete surface at one time. At the same time, it is also necessary to ensure that the pipe is buried more than 2m during the pouring process. Effective measures must be taken to ensure that each pile is poured continuously at one time. During the pouring of concrete, one should stand by and supervise the whole process. The construction unit must fill in the "Punching (Drilling) Hole Grouting Pile Concrete Construction Record". The record should reflect the filling coefficient, cement dosage, pouring time, conduit burial depth, actual hole depth, geological structure and other main contents.

3. Key points of quality supervision of immersed cast-in-place piles:

1. Prior control stage:

1) Review the construction equipment inspection form to understand Check the technical performance and relevant parameters of the pile driver and its supporting devices, and pay attention to review the weight of the counterweight and the fuselage.

2) When testing piles, attention should be paid to determining the maximum pile pressing force and pile length.

3) When the distance between the pile group foundation and the pile center is less than 4 times the pile diameter, the construction unit should propose technical measures to protect the quality of adjacent piles.

2. In-process control stage:

1) After the hole-forming device is in place, it must be straight and stable to ensure that it does not tilt or move during construction. In order to accurately control the depth of the hole, a depth control scale should be set on the pile frame or pile pipe to facilitate observation and recording during construction.

2) The contact between the pile pipe and the pile tip should have good sealing; the whole process of immersed pipe must have a full-time recorder to keep construction records; the current and voltage values ??of the last 30 seconds must be strictly controlled, and the other The value is determined according to the design requirements or based on test piles; after the immersed pipe reaches the design elevation, the supervisor should be notified immediately to detect the pile length. The pile length detection should be used as a stopping point to control. Concrete should be poured immediately after passing the test to minimize the interval; concrete pouring Beforehand, it is necessary to check whether there is any swallowed pile tip or water intrusion in the pile tube; and calculate the theoretical amount of concrete for the pile. The filling coefficient of the concrete shall not be less than 1.0. If it is less than 1.0, it is advisable to drill the whole length again; For piles and necking piles, regional re-driving should be adopted, and the scope of re-driving should exceed the broken pile or necking area by more than 1m.

3). The extubation speed of vibrating immersed cast-in-place piles is preferably 1.2-1.5m/min for general soil layers, and should be controlled at 0 at the junction of soft soil layers and soft and hard soil layers. ?6-0?8m/min; it is better to use the reverse insertion method for pouring concrete, which can effectively compact the space in the hole, has a vibrating effect, and can prevent necking; the concrete must be poured continuously. , and keep the concrete surface in the pipe higher than the groundwater level.

4) Control of concrete slump: When the pile body is equipped with steel bars, the concrete slump should be 80-100mm; plain concrete piles should be 60-80mm.

5) When constructing the full-length repeated piling, it should be noted that the concrete poured for the first time must reach the natural ground, and the axes of the two immersed pipes before and after should coincide. The repeated pouring must be at the beginning of the first pouring of concrete. Complete before setting.

4. Key points of quality supervision of manually dug piles:

1. Pre-control stage:

1) Supervise the construction unit to configure underground safety equipment Miner's lamp and 12V safety lamp. When the excavation depth is greater than 10m, there should be a special device for supplying air underground.

2) Supervise construction units to provide timely technical disclosures on construction safety. The most important thing is how to prevent poisoning and electric shock, so as to ensure safe and accident-free underground construction.

2. In-process control stage:

1). In order to prevent ground rainwater from flowing into the hole, the top surface of the well ring protective wall should be 150-200mm higher than the site, and the wall thickness should be 150-200mm higher than the bottom. The thickness of the well wall is increased by 100-150mm.

2). For each excavation depth of 0.8-1.0m, the back wall expansion movable template is generally: pile diameter/10 50mm, and should not be less than 150mm. The well circle on the same horizontal surface The range of any diameter shall not be greater than 50mm. The concrete pouring for each section of the protective wall should be completed continuously. The removal of the formwork of the protective wall should be carried out 24 hours or after the concrete strength reaches 1.2Mpa. When honeycombs or water leakage are found on the protective wall, they should be reinforced in time to prevent To cause an accident, when encountering regional or mobile silt with a thickness of no more than 1.5m and possible soil and sand surges, the height of each section of the protective wall can be reduced to 300-500mm, and the height of each section of the protective wall can be reduced to 300-500mm, and concrete can be poured, inspected, and , steel casing or effective precipitation measures can also be used. When the diameter of the hole bottom needs to be enlarged, effective technical measures must be taken to prevent quicksand, hole collapse and other phenomena. Supervisors should check whether there is virtual soil and water at the bottom of the hole, the expansion of the hole bottom, and measure whether the hole depth meets the design requirements. .

3) When pouring concrete on the pile body, a chute must be used. When the height is greater than 3m, a string tube should be used. The height of the end of the string tube from the bottom of the hole should not be greater than 2m, and a plug-in vibrator should be used for concrete. Shake up. This process must be supervised on site.

5. Key points for quality supervision of on-site prefabricated square piles:

1. Prior control stage:

1) Before prefabrication, check whether the site is flat and solid .

2) When trial driving piles, attention should be paid to determining the pile length and final penetration when piling is stopped.

2. In-process control stage:

1) On-site production generally adopts the interval overlapping method, and should not exceed 4 layers. The stacking should comply with the specification requirements; concrete strength and mix ratio The design requirements should be met, the slump should be controlled at 60-80mm, and the aggregate should be controlled at 5-40mm; the installation and welding of steel bars must comply with the design and specification requirements. In particular, it should be noted that there can be no joints within 1m of the top of the pile; the formwork must be brushed Isolation agent, new piles can be poured only when the adjacent piles reach 30% of the site. The pouring sequence must be from the top of the pile to the tip of the pile, and the mix ratio must be strictly controlled; the curing time should be no less than 7 days and kept moist; each shift There should be no less than 1 group of concrete test blocks with the same mix ratio. After removing the formwork, check the concrete pouring quality in time.

2) The setting of the lifting rings must comply with the design and specification requirements. The concrete strength must reach 70% of the design strength before it can be lifted, and it can only be transported when it reaches 100%.

3) When driving piles, check the verticality and alignment of the pile frame guide columns. The most important issue is to keep the pile body vertical to ensure that the pile tip is driven into the predetermined depth and that the pile body does not break. At the same time, it should be noted that an elastic liner should be added between the hammer and the pile cap, and between the pile cap and the pile; the pile driving sequence should be determined according to the geological conditions. If it is difficult to drive, the water injection method (sand soil) or the pile planting method can be used. During the piling process, there should be construction records, including pile position, pile frame verticality, hammer weight, drop distance, number of hammer blows per meter, number of hammer blows in the last meter, penetration of each of the last three formations, etc.; Supervision You should stand aside during the entire pile driving process, closely observe the integrity of the pile body, discover problems in a timely manner, solve them in a timely manner, and report to the director immediately when problems cannot be solved.

6. Key points of quality supervision of static pressure pipe piles:

1. Prior control stage:

1) When auditing the construction equipment inspection form, it is necessary to Understand the conversion of the pile driver pressure gauge, the weight of the counterweight, whether the pressure gauge has been certified by the legal metrology department, and what is the validity period.

2) When trial driving piles, attention should be paid to determining the maximum pile pressing force and pile configuration.

2. In-process control stage:

1) Inspection of pipe pile materials. The construction unit must report for inspection in time for each batch of pipe piles entering the site, and supervisors must inspect the pipe piles. If necessary, the production license (especially the validity period of the production license) should be checked, and the appearance of the on-site pipe piles should be checked according to the relevant quotations in the certificate and quality guarantee certificate. Only those that meet the specifications can be put into operation. use.

2) When pressing piles, supervisors should check the verticality of pipe piles at any time (use two theodolite to observe and control in mutually perpendicular directions); when welding piles are used, symmetry should be adopted For welding, it is best to have four welders in symmetrical positions, and there must be at least three welders. This can not only shorten the pile pressing time, but also avoid deformation caused by welding; each weld must be inspected by the supervisor and passed , can the pile pressing be continued. When the maximum pile pressing force is reached, the supervisor should witness the reading of the pressure gauge. Check the weld and read the pile driving force which should be controlled as a stopping point. The construction unit must fill in the pile pressing record, which should reflect the pile pressing force, pile length, pile top elevation, pile pressing time and other main contents.

3) If the pile top or pile body is often found to burst during the pile pressing process, it is necessary to conduct a core test. For example: a construction site pile foundation uses C80 high-strength prestressed pipe piles, but during the pile pressing process, the pile top and pile body are often found to burst. The chief management engineer promptly held a special meeting, and the meeting decided to conduct a core test. The test result was that the concrete strength was C60 , according to the contract, the manufacturer made corresponding compensation.

7. Acceptance of pile foundation projects:

Engineering piles should be inspected for bearing capacity, and the inspection quantity should meet the requirements of the acceptance specifications. All single piles must undergo low strain dynamic testing.

1. After the testing unit enters the site, the supervisor should promptly check the qualification certificate of the test personnel, the measurement verification certificate and the validity period of the test device issued by the legal metrology department.

2. The inspection record of the pile body quality must be signed and confirmed by the supervisor, so the supervisor must track the entire process of supervision and inspection; if a static load test is used, the stacking weight should be checked, and the loading should be checked Whether the number of stages and time meet the specification requirements; each stage of loading must be witnessed.

3. Inspection of pile positions. After excavation, the allowable deviation of pile positions must comply with Articles 5.1.3 and 5.1.4 of the "Code for Acceptance of Construction Quality of Building Foundation Engineering". What is the meaning of water head in pile foundation construction?

Water head is actually a popular term for groundwater pressure. For example, if the groundwater level is -2.0m, then for a place with an altitude of -3.0m, the water head height is 1.0m. Then the groundwater pressure here is 10*1=10KPa. If the water head height is 10m, then the groundwater pressure is 100KPa. Therefore, in the construction of bored piles, the key to the success or failure of drilling is to prevent the hole wall from collapsing. When the borehole is deep, the soil on the hole wall below the water table will collapse into the hole under hydrostatic pressure, and even sand flow may occur. If the water head in the borehole can be maintained higher than the groundwater level and the hydrostatic pressure in the borehole is increased, it can strengthen the borehole wall and prevent collapse.