某深厚软土层基坑双排桩位移影响因素分析

Displacement influencing factor of double-row piles in deep soft soil pit

基坑支护结构变形过大会严重影响基坑和周边建筑物安全。探明影响基坑支护变形因素对基坑设计和施工安全具有重要指导意义。以某深厚软土船闸基坑工程为例,采用有限元软件建立三维模型模拟基坑开挖过程,研究土体参数、临边荷载、桩间土加固强度以及桩体刚度因素对支护结构变形的影响规律,运用灰色关联度理论分析各影响因素敏感程度。结果表明:当土体内摩擦角下降或临边荷载增加,桩顶水平位移增加明显;桩顶水平位移对各因素敏感程度依次为土体参数、临边荷载、桩间土加固强度和桩身刚度。在深厚软土基坑设计与施工中,应重视软土触变、流变问题,提高土体强度并减少支护桩外临边荷载,以保障基坑工程和周围建筑物安全。

The excessive deformation of the foundation pit supporting structure seriously affects the safety of the foundation pit and the surrounding buildings.The proved influencing deformation factors have important guiding significance for design and construction safety.Taking the foundation pit project of a deep soft soil lock as an example,we use the finite element software to build a three-dimensional model to simulate the excavation process,study the influence law of the soil parameters,edge load,the reinforcement strength of soil between piles and pile stiffness factors on the deformation of the supporting structure,and use the grey relational analysis(GRA)to analyze the sensitivity degree of each influencing factor.The results show that when the friction angle in the soil drops or the load increases,the horizontal displacement of the pile top increases significantly.The horizontal displacement of pile top to various factors is soil parameters,edge load,soil reinforcement strength and pile stiffness.In the design and construction of deep soft soil foundation pit,attention should be paid to deformation and rheology of soft soil,improve soil strength and to reduce the external load of supporting pile,so as to ensure the safety of foundation pit engineering and surrounding buildings.