Buried protection tube

    Stake out according to the center of the pile, and draw a circular arc with lime, then manually dig a hole or excavator to dig the hole, put the steel protective tube, and pull the line according to the measured cross pile to make the center point of the protective tube and the measured and calibrated pile position The center points are coincident, and at the same time, the verticality and horizontal position of the protective cylinder are corrected with a line hammer, the inclination rate shall not be greater than 1%, and the deviation shall not be greater than 50 ram. When burying the protective tube, the surroundings should be backfilled with high-quality clay and tamped symmetrically in layers. The inner diameter of the protective tube should be 20-40cm larger than the pile diameter, and the general embedding depth is 200 400cm. When the protective tube is buried, it is 30cm above the natural ground, and a slurry outlet is opened on the top, facing the mud ditch. In special circumstances, the depth of the protective tube can be increased, and the proportion of mud can be increased (the proportion of mud can be increased by pouring clay), and the impact can be slow. Appropriately lower the water level in the protective cylinder. If water is coming from the edge of the protective tube, clay can be used to fill and reinforce the protective tube. Severe sinking or displacement should be reworked and re-embedded; if the wall of the punching hole leaks, the clay or green potassium (mud powder) can be recycled to make slurry, thereby increasing the proportion of mud; after the protective tube is buried, it should be used Line hammer and wooden ruler, measure the distance from the edge of the protective tube to the center of the pile in the cross direction (or in the horizontal direction of the route), and make the original construction records. It is best to use a total station to measure the center of the protective tube to the pile position Deviation, the deviation shall not be greater than 5em. And bury protective piles around the mouth of the protective tube (buried in the direction of the cross and draw four marks) so that operators and quality inspectors can use the cross method to find the center of the pile.

     Rig in place

     Place the rig in place, set up the drill stand, and aim it at the center of the hole, as shown in Figure 1. The drilling rig is located on the side of the drilling steadily, and the supporting skid at the bottom of the drilling rig shall not be pressed on the steel casing of the hole. After the rig is installed in place, the bottom and top should be stable to ensure that the rig will not move or sink during the drilling process. Choose the matching drill cones and drilling accident handling tools for suitable formations, connect the water and electricity supply, and prepare the mud-making clay and slag drainage ditch. Adjust the rig so that the rim of the rig lifting pulley, the center of the drill cone and the center of the pile hole are on the same vertical line to stabilize the rig.

     Qing Kong Cheng Kong

     After drilling to the design depth, after the consent of Party A and the supervising engineer, the rushing will not be continued, and then the empty rushing will not be carried out. The cyclic slurry cleaning is an important link to ensure the quality of the punched pile. It must not be underestimated. Re-check the mud specific gravity, sand content and sediment thickness. When the mud specific gravity, sand content and thickness of the sediment exceed the specified values, the holes must be cleaned again and can be poured after passing the test.   

      Installation of steel cage

      During lifting, attention should be paid to prevent the steel cage from being deformed too much. When lifting in sections, it should be prevented from twisting and bending. When installing, you should align the hole position, hang straight and stabilize, sink slowly to avoid colliding with the hole wall, sink to the design position, and fix it immediately. The two main bars of the elongated steel cage and the hole protector should be temporarily welded; during installation, The pile shall be inspected and accepted for concealed works in conjunction with the owner, supervision, quality inspection and other departments, and the second hole cleaning shall be carried out after passing the test. Pour the pile foundation concrete only after the specific gravity and sand content of the second cleaning mud meet the specifications or design requirements. The intermittent time of pouring should not exceed 4h, and the sediment thickness must be re-measured before pouring.  

     Pouring underwater concrete

     The thickness of the sedimentation layer should be checked before pouring the concrete. The thickness of the sedimentation layer should be controlled within 300 ram. If the thickness exceeds the regulations, use an air compressor to float. The concrete pouring adopts the catheter method, and the pouring concrete is uniformly commanded by one person to order the ball, and the pouring speed must be gradual. The bottom of the pipe is buried in the poured concrete mixture at an appropriate depth. When pouring the first batch of concrete, the distance from the lower mouth of the pipe to the bottom of the hole is generally 25-40cm, and the depth of the pipe should not be less than lm when the concrete poured for the first time. During the pouring process, you should always use a hundred-meter rope to detect the position of the concrete surface in the hole, and adjust the buried depth of the conduit in time. The buried depth of the conduit should be controlled between 2-6m. When removing the conduit, it is controlled to remove only one section at a time (2~ 2.5m). In order to prevent the reinforcing steel skeleton from floating up, when the top surface of the poured concrete is about 1IIl from the bottom of the reinforcing steel skeleton, reduce the speed of concrete pouring. When the concrete rises to 4m above the bottom of the reinforcing steel skeleton, raise the pipe so that its bottom is 2m higher than the bottom of the skeleton , The normal perfusion rate can be restored. Cut off and remove the pile before it, prevent damage to the pile body when cutting the pile, and there should be no loose layer at the pile head. When the pile is cut, the main reinforcement of the pile head can be slightly bent outward, but the angle shall not be greater than l5.