The mechanical equipment for hammering sunk pipe cast-in-place piles consists of pile pipe, pile hammer, pile frame, hoist pulley block and walking mechanism.

     Hammered sinking pipe piles are suitable for general cohesive soil, silty soil, sandy soil and artificial fill foundations, but cannot be used in dense sand gravel and boulder layers. Its construction procedure is generally: positioning and burying the concrete prefabricated pile tip → pile machine in place → hammering sinking pipe → pouring concrete → pulling out the pipe, hammering, and continuing to pour the concrete (inserting the lifting cage in the middle) → forming the pile .

     During construction, use the pile frame to lift the steel pile pipe and aim it at the buried precast reinforced concrete pile tip. The connection between the pile pipe and the pile tip should be lined with sack and straw rope to prevent groundwater from infiltrating into the pipe. Put down the pile pipe slowly, press the pile tip into the soil, buckle the pile cap on the upper end of the pile pipe, check whether the pile pipe and the pile hammer are on the same vertical line, and the pile pipe verticality deviation is less than 0.5%. Sink the tube. Lightly hit with a low hammer first, observe that there is no deviation, and then perform normal operation until the pile sinking elevation meets the design requirements, and check whether there is mud or water in the pipe, then concrete can be poured. The concrete in the pipe should be filled as much as possible and then the pipe should be pulled out. When pouring the pile body concrete with a steel cage that does not reach the bottom of the hole, the first time the concrete should be poured to the elevation of the bottom of the cage, the steel cage should be placed, and then the concrete should be poured to the elevation of the pile top. The height of the first extubation should be limited to the amount of concrete that can accommodate the second filling, and it should not be pulled too high. In the process of extubation, a special measuring hammer or buoy is used to check the drop of the concrete surface.

     The concrete strength grade of hammered sunk pipe piles shall not be lower than C20, and the amount of cement per cubic meter of concrete shall not be less than 300Kg. The slump of concrete should be 80-100mm when the steel is equipped, and 60-80mm when there is no reinforcement. The particle size of the crushed stone is not more than 25mm when equipped with steel bars and not more than 40mm when there is no reinforcement. The strength grade of the precast reinforced concrete pile tip shall not be lower than C30. The concrete filling factor (the ratio of the actual pouring concrete volume to the volume calculated according to the design pile diameter) shall not be less than 1.0, and the elevation of the pile body concrete top surface after the pile shall be at least 500mm higher than the design elevation.