Registered geotechnical engineer examination of the tree root pile construction provisions?
1, pile plane deviation ± 20mm; straight pile verticality and inclined pile inclination deviation should be according to the design requirements shall not be greater than 1%.
2. Drilling machine can be used to make holes through the original foundation concrete. In the soil layer drilling is appropriate to use water or natural mud wall, can also be used casing.
3, reinforcing cage should be lifted whole. When the subsection lifting, the length of the intersection reinforcement lap weld double-sided welding shall not be less than 5 times the diameter of the reinforcement. One-sided welding shall not be less than 10 times the diameter of steel. Grouting pipe should be inserted straight to the bottom of the hole. Need to second grouting tree root pile should be inserted two grouting pipe, construction should be shortened lifting and welding time.
4, when using crushed stone and fine stone filler, the filler should be cleaned, the input should not be less than 0.9 times the volume of the calculated pile hole, filling and filling should be filled at the same time with grouting pipe water to clear the hole.
5. The grouting material can be cement slurry, cement mortar or fine stone concrete, and the grouting shall be cement slurry when gravel is used for filling.
6, when the use of a grouting, the maximum working pressure of the pump should not be less than 1.5MPa, the beginning of grouting, the need for 1MPa starting pressure, the slurry through the grouting pipe from the bottom of the hole pressure, followed by the grouting pressure is appropriate for the 0.1-0.3MPa, so that the slurry gradually up until the slurry flooded out of the mouth of the hole to stop grouting.
When the second grouting, the maximum working pressure of the pump should not be less than 4MPa. The second grouting can be carried out only when the first grouting of the slurry is beginning to solidify, and the initial solidification time of the slurry is determined according to the cement varieties and admixture of additives, and it can be controlled in the range of 45-60min. The second grouting pressure should be 2-4MPa, the second grouting should not use cement mortar and fine stone concrete.
7, grouting construction should be spaced construction, intermittent construction or increase the mixing amount of quick-setting agent and other measures to prevent the adjacent pile slurry and string hole phenomenon. Tree root pile construction should not appear necking and collapse hole.
8. After pulling out the pipe, the top of the pile should be filled with gravel immediately, and supplementary grouting should be carried out in the range of 1-2m.
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