1, preparatory work (1) Install the hoist: ① The distance between the hoist and the pile hole should be controlled at about15m, not too far. If the distance is too large, the steel wire rope will swing too much during impact, which will cause great impact energy loss and be unsafe. At the same time, it affects the line of sight, and it is difficult to control the height of the hammer, especially at night, which is easy to empty the hammer and cause accidents. (2) The drum of the hoist should be aligned with the notch of the ground pulley to prevent the wire rope from being twisted out of the groove and causing danger. (3) The ground anchor must be set behind the hoist, which is connected with the hoist to pull the hoist to prevent it from moving forward. (2) Connection of impact system:
① Connection between the steering ring and the hammer: Place the prepared connecting ring (round steel with a diameter of 50 mm and a length of about 1 10 ~ 120 cm) at the lower end of the steering ring, and then weld the two feet of the connecting ring firmly with a hammer. The weld length is not less than 30 cm.
② Connection between the hoist and the impact hammer: One end of the main steel wire rope is fixed on the hoist, and the other end is connected with the upper end of the steering ring through the ground pulley and the top pulley. In order to increase the stress radius of the wire rope in the bending part and prolong the service life of the wire rope, a special groove-shaped iron guard is installed in the bending part of the wire rope. The first buckle of the consolidated wire rope should not be screwed too tightly, so as to avoid the wire rope being injured and broken here after being stressed. Generally, three buckles are used, and the spacing between the buckles should not be less than 6 times the diameter of the wire rope.
(3) Buried barrel:
① Excavation: the excavation depth is 0.5 ~1m.. The barrel mouth must be at least 50 cm above the ground to keep the water level in the hole higher than that outside the hole or on the ground, to increase the water pressure in the hole and to protect the hole wall from collapse. After the foundation pit is dug, put the bucket.
(2) Backfilling: firstly, put clay (rake mud) with a thickness of about 20 cm on the bottom of the outer periphery of the barrel, and stamp it with your feet, then pile up loess straw bags, alternately stack them to form a layer of straw bags, then lay another layer of clay, and then lay another layer of clay, and stamp it to make it slightly lower than the barrel mouth by about 20 cm. Loess straw bags and clay must be compacted layer by layer, which can not only prevent the river from infiltrating, but also fix the bucket.
③ Preparation of wall protection materials: If the surface is soft soil, flaky, crushed stone and loess are added into the bucket, with the ratio of about 3: 1: 1. If the surface is gravel, only pebbles (small gravel) and loess are added in the bucket, and the ratio is roughly 1: 1. All these jobs should be finished before drilling.
2. Mesoporous
(1) Opening: In the opening stage, the punching progress should not be too fast. The footage of a general console is within 1 meter. Accordingly, the height of the lifting hammer should be smaller and the impact times should be more (see the table below). As a result, the impact force is small, and the hole wall is gradually squeezed and compacted by horizontal force.
Height of earth lifting hammer (cm) Impact times (times/minute) Mud concentration
Soil 40 ~ 60 20 ~ 251.4 ~1.5
Gravel 40 ~ 60 20 ~ 251.5 ~1.7
At this time, if the impact is too great and the progress is too fast, the hole wall can not be well formed, but it will cause hole collapse. Therefore, the punching progress should be strictly controlled and the hole wall should be strengthened in the opening stage. It is required to protect the hole wall as firmly as possible in the range of hole depth and 3 ~ 4 meters below the bucket bottom, and then it is not easy to collapse when entering normal drilling.
(2) Normal drilling: After the drilling stage of slight impact is over, normal drilling is started to speed up. The height of the hanging hammer can be increased to more than 1.5 ~ 2 meters, and the mud concentration is correspondingly reduced, which is roughly below 1.5. In general, the drilling footage per shift is about 1 ~ 1.5m, sometimes more.
(3) Bored rock stratum: The surface of rock stratum is mostly uneven or inclined, so when drilling just enters the rock stratum,
Eccentric holes are most likely to occur. Therefore, special care should be taken when drilling holes to contact rock strata. Usually, flaky with a diameter of 20 ~ 30 cm is thrown at the bottom of the hole to fill the inclined plane and unevenness of the rock stratum. Then tighten the rope and impact quickly with a low hammer, so as to form a relatively compact platform to support the impact hammer, uniformly stress and prevent the hole from being eccentric. However, it should be noted that the hammer cannot be lifted before the inclined protruding part of the rock stratum is leveled, and the hammer can be hammered with a high hammer after the rock stratum is basically leveled, so as to speed up the drilling process.
After rushing into the rock stratum, the mud concentration will be reduced to about 1.2 to reduce the resistance and hammer jam, but it should not be too small, otherwise the stone slag will not float up and it is difficult to dig out the slag.
Step 3: Dig out the slag.
In the process of drilling, a part of stone slag and mud are squeezed into the gap of the hole wall, and most of them are carried away by the slag bucket. In the opening stage, in order to make the stone slag mud and stones squeeze into the pores around the hole wall as much as possible to strengthen the hole wall, the stone slag is not removed during the impact process, and it is removed once after reaching 4 ~ 5 meters to reduce the mud concentration. In the normal stamping stage, slag should be removed in time, otherwise the resistance is too great, which is not conducive to impact. Generally, the slag is cleaned once per machine-team, and 4 ~ 5 barrels of stone slag mud are taken out at a time, but two points should be paid attention to when cleaning the slag:
(1) Add water to the hole in time, keep the water level in the hole at a necessary height, and avoid hole collapse due to the decrease of water pressure.
(2) After the stone slag is removed, the wall protection material should be added to the hole immediately to restore the mud to normal concentration. Such cyclic replacement can ensure the smooth drilling. As for rushing into the rock stratum, it is usually once per machine shift, and 5 ~ 6 barrels of slag slurry are pulled out at a time.
4. Put down the reinforcing cage
In order to facilitate the hoisting of the reinforcing cage, the reinforcing cage should not be too long, and every 8 ~ 10 meter is saved. Therefore, the length of reinforcing cage can be segmented and bound according to the depth of pile hole and its total length. In order to increase the hoisting rigidity of the reinforcing cage, temporary measures can be taken to tie logs with a diameter of about 15 cm in the middle of the reinforcing cage, which is half the length of the reinforcing cage. When the reinforcing cage is vertical, the log will be lifted.
According to the height of the tripod and the length of the reinforcing cage, the following methods are adopted for hoisting:
Reinforcing cages should be hoisted in sections, but a single-leg boom should be erected at the upper end of the tripod to increase the hoisting height. Hoist the reinforcement cage in the first section into the hole and lift it, that is, lift the second section, weld the first section, dismantle the facilities for hoisting the reinforcement cage after welding, and then continue the hoisting.
When lifting and lowering the reinforcing cage, the lifting speed should be controlled. Hoisting should be slow and even, so that the reinforcing cage can slowly rise along the tripod feet and gradually stand up. Excessive lifting may deform the reinforcing cage. After the reinforcing cage is hoisted and erected, it should be lowered slowly in a straight line to prevent the reinforcing cage from swinging in the hole. Collision with the hole wall, resulting in hole collapse.
5. Borehole cleaning
After the reinforcing cage is put down, the hole cleaning work shall be carried out.
(1) Installation hole cleaner:
Near the orifice, put two sections of hole cleaning conduit together to form several large sections. Connect the lower intake pipe and install the upper nozzle elbow. Then use the top pulley of the hanger to lift it in turn. Hang the bottom section into the hole first, and then hang it in the right position. Then, hang the second section for connection, and so on until the whole catheter is installed. The conduit should be 3 ~ 4 meters above the ground, and the nozzle should be aligned with the outlet. In order to prevent the catheter from rotating, two logs should be used to clamp the catheter, that is, to control the direction of water spraying and to hold the catheter down. At the same time, connect the water source. After hole cleaning, water should be poured into the hole to keep the water level in the hole and avoid hole collapse.
(2) hole cleaning:
The air compressor and water pump are started at the same time. The air pressure of the air compressor is not less than 6 ~ 7kg. According to the general principle of the sand blower, the air compressor continuously delivers high-pressure air into the conduit, and a generally powerful high-pressure airflow runs upward in the conduit. The stirred sludge flows upward with the high-pressure airflow and is ejected from the nozzle (as shown in the following figure) until clear water is ejected from the orifice. In this way, pebbles generally smaller than the diameter of the hole cleaning pipe can be removed, and only a few pebbles larger than the diameter of the hole cleaning pipe remain at the bottom of the hole, which is harmless to the quality of concrete.
According to practical experience, it is considered that this hole cleaning method can basically meet the requirements.
6. Pouring underwater concrete
(1) Install the catheter:
(1) At the same time of hole cleaning, prepare to pour concrete, and make preparations before hole cleaning is completed. After hole cleaning, remove the hole cleaning equipment, take out the hole cleaner, and then lift the concrete conduit. The concrete conduit must be pre-assembled, divided into several sections and arranged in turn for hoisting. Requirements for conduit: it must be straight, without uneven bending, so as not to hinder the falling of water polo; The bolts connecting the flange of the conduit shall be tightened to avoid water leakage and slurry leakage.
(2) Suspend the concrete conduit with a tripod.
(3) The conduit shall be placed in the center of the pile hole and fixed. The lower outlet is 30 ~ 40 cm away from the bottom of the hole, not too big. The diameter of the conduit used here is 30 cm, and the waterproof ball of concrete is also large, so the outlet of the conduit is far from the bottom of the hole, so the concrete that flows out at first is washed with heavy water. The diameter of the conduit should be 20 or 25 cm, and the size of the waterproof ball should be reduced, so that the distance between the conduit mouth and the bottom of the hole is controlled within 30 ~ 35 cm, and the concrete scouring phenomenon can be reduced. The top of the conduit is 3 ~ 4 meters above the ground or water surface, and the water isolation ball is suspended below the water surface (as shown in the following figure).
(2) pouring concrete:
(1) the fluidity of concrete should not be too large, and its slump is generally controlled at 18 ~ 20cm.
(2) Enough concrete must be reserved before cutting the ball, and the calculation must make the concrete buried in the conduit 50-60 cm deep. After the ball is cut, the concrete must be continuously lowered into the funnel to avoid interrupting the concrete in the conduit.
(3) Control the depth of the conduit buried in concrete. Generally, when the lower part of the conduit is buried in concrete for 2 ~ 2.5 meters, it is necessary to lift the conduit. Care must be taken to prevent the conduit from being lifted off the concrete, so as to ensure that the lower end of the conduit is still buried in the concrete by about 100cm, so as to avoid the frost boiling accident. If buried too deep, it will be difficult to lift the pipeline.
(4) After the concrete is finished, remove the bucket.