1, the wall thickness of the catheter is not less than 3mm, and the diameter is 200 ~ 250mm；; The manufacturing deviation of the diameter should not exceed 2mm, and the sectional length of the conduit should be determined according to the technological requirements. The length of the bottom pipe is not less than 4m, and the length of other pipe sections is 2.53m, and the joint adopts double-thread square buckle quick joint.
2. Before the catheter is used, it should be assembled and pressure tested, and the water testing pressure is 0.6 ~1.0 MPa;
3. Clean the inside and outside of the catheter after each perfusion.
The quality control of pouring underwater concrete should:
1, when pouring concrete, the distance from the bottom of the conduit to the bottom of the hole should be 300 ~ 500mm；;
2. There should be enough concrete reserves, and the conduit should be buried below the concrete pouring surface not less than1.0m; ;
3. The depth of the conduit buried in concrete should be 2 ~ 6m. It is forbidden to lift the catheter away from the concrete pouring surface, and the speed of lifting the catheter should be controlled. There should be a special person to measure the buried depth of the conduit and the elevation difference of the concrete pouring surface inside and outside the conduit, and fill in the underwater concrete pouring record;
4, pouring underwater concrete must be continuous construction, the pouring time of each pile should be controlled according to the initial setting time of the initial plate of concrete, and the faults in the pouring process should be recorded for the record;
5. The last grouting amount should be controlled, and the over-grouting height should be 0.8 ~1.0m. After the submerged height is chiseled, the concrete strength of exposed pile top must reach the design level. After each pile is poured to the top, attention should be paid to the super-high quality of 800mm, and the contractor should check the elevation. Elevation according to the design elevation plus 800mm for inspection.
Before grouting, the water content and specific gravity of mud must be controlled, which is a very important factor affecting the quality of pile foundation.
Underwater concrete pouring shall meet the following requirements:
1, underwater concrete must have good workability, and the mixture ratio should be determined through experiments; Slump should be180 ~ 220 mm; Cement dosage is not less than 360kg/m3 (when mixed with fly ash, the cement dosage is not limited);
2. The sand content of underwater concrete should be 40% ~ 50%, and medium coarse sand should be selected; The maximum particle size of coarse aggregate should be less than 40mm；; And should meet, coarse aggregate can choose pebbles or gravel, aggregate particle size shall not be greater than 0/3 of the minimum spacing between reinforcement.
3, underwater concrete should be mixed with additives.
4. The initial pouring amount of concrete must be calculated and determined: generally speaking, the depth of the conduit inserted into the concrete in the pile is required to be1500mm; ;
5, hole depth must comply with the design requirements, sediment thickness is strictly prohibited to be greater than 50 mm ..
6. The initial pouring amount of concrete shall ensure that all the water in the conduit is squeezed out, and the conduit can be buried in concrete 1 ~ 1.5m for the first time. ..