A construction method for anti-uplift deformation of foundation pit excavation above existing tunnel

Abstract

The invention discloses a construction method for anti-uplift deformation of foundation pit excavation above an existing tunnel. Initial grading and soil nailing and anchoring, initial grading and soil nailing and anchoring from the periphery of the foundation pit, foundation pit enclosure and internal support, and secondary grading from the reserved core soil Slope and soil nailing and anchoring support, excavation of connecting grooves, application of grouting pipe curtains, segmental hopping and excavation to reserve core soil. The invention adopts the combination of stratum pre-reinforcement and grouting pipe curtain, which can effectively increase the stiffness of the stratum and prevent the stratum from floating, thereby controlling the deformation value of the existing tunnel structure, ensuring long-term stable operation of the tunnel, and having a wide application range. The invention adopts the method of reserving the undisturbed core soil above the tunnel, which can ensure that the overlying gravity of the tunnel continues to exist, and has little interference with the stability of the underground structure.

Description

technical field [0001] The invention belongs to the field of excavation construction methods of foundation pits, and in particular relates to a construction method for anti-uplift deformation of foundation pit excavation above existing tunnels. Background technique [0002] With the acceleration of the urbanization process, a large number of subway and foundation pit projects have emerged, and the scale has continued to increase. In view of the construction timing problem, there must be subsequent excavation of foundation pits that need to be constructed above or adjacent to existing underground buildings such as subways and tunnels. Excavating the foundation pit above the existing tunnel will inevitably lead to the release of ground stress and the rebound of the basement, and the deformation of the soil will also lead to changes in the stress field and displacement field of the tunnel. When the deformation of the tunnel exceeds a certain limit, water leakage at the tunnel ...

AI Technical Summary

Problems solved by technology

When the deformation of the tunnel exceeds a certain limit, there will be water leakage at the joints of the tunnel, and it will have a greater impact on the safe operation of the tunnel in severe cases, resulting in the inability to operate safely

[0003] At present, traditional foundation pit construction methods often use large-area soil reinforcement and structural reinforcement technologies, and it is difficult to avoid the base from rebounding again after unloading after loading

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