September 28, 2022
What is Drill-Pouring Pile?
The drill-pouring pile is a kind of technology that uses different drilling methods to form a certain shape (section) of the good hole in the stratum according to the requirements. After reaching the design elevation, the steel skeleton is lifted into the good hole and the concrete is re-perfused.
The Construction Process of the Bored Pile
1. Construction Preparation
Before drilling, the debris on the platform should be removed, and the placement position and direction of the pile driver, the stacking of steel cages, the placement of cranes, and the placement of concrete pouring should be planned. Pile the machine under the steel pipe to put a layer of a sleeper to prevent pile machine displacement.
2. Measurement Lofting
The measurement class put out the pile center point, the construction team pulled the pile line. The location of the pile should be ensured not to hinder the mechanical operation, to avoid damage to the pile.
3. Buried Casing
The inner diameter of the casing is 30cm larger than the pile. A crawler crane and vibrating hammer are used to bury the casing. The buried depth is determined according to the field situation (the casing passes through the medium sand layer to the gravel layer ), and the top of the casing is flush with the platform surface. The deviation between the center of the top surface of the casing and the designed pile position is not more than 5cm, and the inclination is not more than 1%.
4. Mud Pool
The mud pool adopts an adjacent pile foundation casing, and the mud is configured with bentonite(or high-quality loess), caustic soda, cement, etc., and the natural mud is made by the up and down impact of the pile hammer.
5. Measurement Review
After the casing is buried; on-site technicians use a level to measure the top elevation of the casing; notify the measuring class to check whether the casing is centered.
6. Fill in the Construction Mark of the Bored Pile
The site technician shall calculate the drilling depth and fill in the drilling pile construction sign.
7. Inspection before Drilling
Check whether the diameter and weight of the impact hammer meet the construction requirements of the pile foundation (the drill bit adopts a plum-shaped drill bit with a spherical arc surface. Drill diameter is generally smaller than the pile diameter 80 ~ 100mm); whether the installation position of the drilling rig is correct (the front edge of the lifting pulley, the center of the drill bit and the center of the pile are on the same vertical line, and the deviation between the vertical line and the center of the pile should be controlled below 20mm).
Start drilling, footage should be properly controlled, at the foot of the casing blade, should be short stroke drilling, so that the foot of the blade has a strong mud wall. When the drilling depth exceeds the full height of the drill bit, it can be drilled at normal speed. During the drilling, the construction team should make drilling records and take slag samples. The on-site technicians check every day to see whether the drilling slag situation is consistent with the design, regularly check whether the drilling hole is inclined, and measure the diameter of the hammer.
9. Rebar Processing Workshop Processing Steel Cage
10. Pore Inspection
After the hole is formed, the technician retests the elevation of the casing with the level gauge and checks in time whether it reaches the pile length. Use a rope to measure hole depth and use a 50 m steel ruler to calibrate the rope to see if it is accurate. After no error by the project quality inspection engineer reported to the Office of the Director of a hole detection.
11. First Clear Hole
After the hole is formed, the drill bit is raised to 30-50 cm from the bottom of the hole, and then the first hole is cleared with a large pump until the indicators meet the requirements, and then the next process is carried out.
12. Lowering the Steel Cage
Notify the steel workshop to transport steel cages to a construction site. Steel cage installation using a truck crane. Before lowering the reinforcing cage, the hole detector should be lowered to check the hole formation, and the reinforcing cage should be lowered after passing the inspection.
13. Steel Cage upper-end Positioning
The positioning of the top end of the steel cage must be calculated by the measured elevation of the top of the casing, and the length of the suspension bar should be welded after repeated checking. The deviation between the center plane of the reinforcement cage and the center of the pile is controlled within 20 mm, and the allowable error of the top height of the skeleton is controlled between ± 20 mm.
14. Install Catheter and Secondary Hole Cleaning
Perfusion concrete is poured through a steel pipe with an inner diameter of 300 mm; the watertight pressure bearing test and joint tensile test should be carried out before the pipe is used. The distance between the bottom of the pile hole and the bottom of the pipe is generally controlled at 30-40 cm. After the catheter is installed, perform secondary hole cleaning. After the completion of the second hole cleaning, check the sediment thickness and mud-specific gravity and other indicators, and prepare to fill the concrete after passing.
15. Pouring Concrete
Notify the mixing station and laboratory to send concrete. The first batch of concrete pouring should be able to meet the needs of the first buried depth of more than 1m catheters. during perfusion; catheter buried depth should be controlled at 2-6m, at any time with the measuring rope to detect the position of the concrete surface in the hole and timely adjustment of the buried depth of the catheter. The thickness of concrete pouring should be more than 0.5m than the design value to ensure the quality of pile head concrete.
The buried depth of the conduit should be controlled between 2 and 6 meters.