Original soil filling pile construction method
1The excavation of the pipe jacking pit shall be carried out according to the construction scheme and specific environment. The length and width of the pit depend on the soil, the diameter and length of the top pipe section, the mechanical equipment, the pipe down and the method of excavation. In addition to installing the back of mechanical equipment for pipe jacking, guide rail and pipe jacking section, the working pit is also conducive to excavation and operation of staff outside the pit. It is generally required that the leading edge of the upper mouth of the working pit is away from the curb≥2mEach side placed after the tube section should be1mOn the working surface, the rear side of the pipe joint and the jack should be conducive to the excavated space. Puddles and drainage facilities should be provided in an environment with water. The slope coefficient of the working pit wall should be based on the soil condition, and the pit bottom should be rammed.
2The guide rail is composed of four rails and several sleepers. The sleepers are placed under the work pit1/2Sleeper height is based on sleeper spacing800 ~1000mm, the length of the track is equal to the length of the bottom of the working pit minus the position of the track pile. The track spacing depends on the outer diameter of the top pipe joint. In general, the lower skin is elevated above the sleeper epithelium after placement of the tube segment20mm, after installing the jack, there should be a maximum contact surface with the cross section of the pipe section, the rail should be straight, and the front end head should be0.5-1.0%The slope.
3Pushing into the back: the firmness of the back directly affects the effect of pushing the tube. Therefore, the ability of the back must be able to meet the needs of maximum lift. The back consists of the back pile, the back beam and the rammed earth behind the back pile. The back piles are generally replaced by rails and buried below the bottom of the pit1.5mOn the left and right, the pile backpacking is layered and compacted, the plane of the back pile is perpendicular to the top direction axis, and the steel back beam is placed on the front guide rail of the pile. Other compositional types of jacking backs include masonry rubble and precast reinforced concrete blocks.
4, jacking equipment and pipe joint installation:The jacking equipment consists of one high-pressure oil pump and two pumps200~500tIt is composed of a jack, which is installed between the back beam and the pipe joint. There is a special steel guard ring, hemp or rubber pad between the rear end of the pipe joint and the jack to protect the concrete pipe end. The wall is coated with paraffin as a lubricant to reduce jacking friction resistance. The jack enters the top of the pipe joint into the subgrade through the force transmission column.
5, digging, jacking, measurement and correction: after the installation of equipment, after the test run without abnormal soil jacking. The excavation depends on the thickness of the soil and soil covering on the upper part of the pipe, and the depth of the inlet ruler is mastered. The soil is dense and covered with thick soil, which is conducive to the formation of unloading arch. Can be appropriate to dig more. Dig less if the soil is loose or the overburden thickness is small. Frequent excavation of frequent roof, excavation diameter shall not exceed the outer diameter of pipe joint.
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