软土基坑预制桩支护对周边建筑影响的实测及数值分析

Numerical analysis and in situ-monitoring on mutual influence to surrounding buildings around soft soil pit retained with prefabricated piles

预制桩用于基坑支护具有施工速度快、经济性显著的优点,在满足支护结构强度及变形控制要求情况下深受市场欢迎。但是预制桩支护同时也具有密集挤土效应,因此导致建筑物在支护桩施工及基坑开挖全过程中发生隆起—沉降变形。本文以某软土基坑预制桩支护施工过程为实例对其周边建筑物进行了全过程监测。监测结果表明,在支护桩施工期间建筑物先迅速隆起,后在基坑开挖期间缓慢沉降。建筑物隆起及沉降均在基坑中部最大,具有显著空间效应。同时,采用有限元数值分析进一步表明,建筑物基础对基坑周边土体的变形形态有一定的影响。

The prefabricated piles have the advantages of fast construction speed and low cost when used in pit support. When the strength and deformation meet engineering requirements,the prefabricated piles are widely used. But the prefabricated piles also have intensive compaction effect,which cause the buildings subsidence deformation and uplift in the whole process of the pile construction and pit excavation. Taking the soft soil pit supporting construction process with prefabricated piles for the whole process monitoring of the surrounding buildings as the example,the monitoring results show that during the retaining pile construction the buildings rapidly uplift,then during the excavation of the foundation pit the buildings slow subside. The maximum values of the uplift and settlement are at the central part of the foundation pit,which have the obvious spatial effects. At the same time,the finite element numerical analysis further shows that buildings foundation has impact on the deformation of soil around foundation pit.