Considering the characteristics of the surrounding environment and the stress of the horizontal support system of this project, the principle of excavation of foundation pit supporting construction is as follows: 1. Before earthwork excavation of foundation pit supporting construction, detailed earthwork excavation construction organization design should be prepared. 2, foundation pit supporting construction earthwork excavation should strictly implement the principle of "stratification, segmentation, symmetry and balance".
Considering the characteristics of the surrounding environment of the project and the stress of the horizontal support system, the excavation principle of the foundation pit supporting construction is as follows:
1Before earthwork excavation of foundation pit retaining construction, detailed earthwork excavation construction organization design should be prepared.
2The principle of "stratification, segmentation, symmetry and balance" should be strictly implemented in earthwork excavation of foundation pit supporting construction.
3Foundation pit earthwork is divided into seven layers, using partition and block to support the excavation, the first layer excavation to the first support bottom; The third layer is excavated to the second supporting bottom; The fifth layer is excavated to the third supporting bottom; The eighth layer was excavated to the bottom of the pit.
4According to the subdivision of soil excavation, the temporary support system is poured into blocks for bracing, and the principle of space-time effect is used to speed up the formation of the support system and reduce the deformation of the enclosure.
5The earthwork around the foundation pit should be excavated at intervals in segments, and the segment length of the common area should not be greater than30m.
6The thickness of the layered sections in excavation operation for foundation pit supporting construction is not greater than3Meters from the bottom of the pit3mPosition, the thickness of the layer is not greater than 1.5m. Excavation above design elevation is strictly prohibited. The bottom of the pit should be preserved0.3mThick foundation soil, using manual excavation leveling, and prevent the bottom of the pit soil disturbance. Concrete cushion layer should be dug with pouring, that is, the cushion layer must be at the bottom24 Finish pouring within hours. In order to reduce the exposure time of foundation pit and the deformation of retaining pile, pile head chiseling and reinforcing bar binding should be carried out after concrete reaches a certain strength.
7Mechanical collision is strictly prohibited on the parapet wall, engineering pile, support, column and well point. When excavating the soil, the column should be hollowed out around the first to avoid the column to bear uneven lateral earth pressure.
8A large number of pile load is strictly prohibited on the edge of the foundation pit, and the ground overload should be controlled in15KN/㎡Within, and strictly control the uneven load. Mechanical inlet and outlet channels shall be laid with subgrade box diffusion pressure, or partially reinforce the foundation.
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