某深厚软土层超大基坑支撑结构偏移险情原因分析及加固措施探讨

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

本文介绍了某深厚软土地区超大深基坑由于开挖顺序不合理引起的内支撑出现偏移险情的工程实例。该基坑土层开挖范围内以软土为主。由于4#主撑范围南、北两侧土方未对称开挖,在主撑下方形成了约6 m的高差,对支撑及临时立柱产生了附加的水平向推力,导致4#主撑出现了较大偏移。通过有限元模拟对比了偏移前后支撑受力情况,得出了变形后的支撑需进行加固处理后方可满足设计要求的结论;结合现场实际情况,提出了支撑加固措施并给出了4#主撑处合理的加固及基坑开挖工序,确保了基坑安全。

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.