Cause Analysis and Reinforcement Measures for the Dangerous Situation of the Deviation of the Super-Large Foundation Pit Support Structure in a Deep Soft Soil Layer

Abatrct: This article introduces an engineering example of a super large deep foundation pit in a deep soft soil area where the internal support was prone to displacement due to an unreasonable excavation sequence. The excavation range of the foundation pit soil layer is mainly composed of soft soil. Due to the asymmetrical excavation of the earthwork on the south and north sides of the main support 4 #, a height difference of about 6 m was formed below the main support, which generated additional horizontal thrust on the support and temporary columns, resulting in significant displacement of the main support 4 #. The stress situation of the support before and after displacement was compared through finite element simulation, and it was concluded that the deformed support needs to be reinforced before it can meet the design requirements; Based on the actual situation on site, support and reinforcement measures were proposed, and reasonable reinforcement and excavation procedures for the main support 4 # were provided to ensure the safety of the foundation pit.