考虑渗流影响的基坑临近地基承载力FELA分析

Finite Element Limit Analysis of Bearing Capacity of Strip Footing near Foundation Pit Subjected to Seepage

研究目的:基坑施工将使临近地基承载力下降,进而对临近结构产生附加影响。考虑目前基坑临近地基承载力的研究中通常忽略渗流的影响,因此本文采用有限元极限分析法对渗流环境下的基坑临近地基承载力进行计算分析,研究条形荷载、锚杆、地下水位与填土强度等对基坑临近地基承载力的影响。研究结论:(1)通过对比发现,有限元极限分析法计算值接近传统弹塑性有限元法以及极限平衡法计算结果,同时前者的计算速度更快;(2)与不考虑渗流工况时相比,当条形基础的宽度较大且距离基坑较近时,渗流环境将使临近地基承载力显著减小;(3)基坑临近地基承载力随着坑内外水头差的增大呈先减小后缓慢增大的趋势;(4)在基坑中上部增加锚杆支护可以有效提高基坑临近地基承载力;(5)基坑临近地基承载力随着填土强度的增大近似线性增大;(6)本研究结果将为基坑临近建筑物设计提供借鉴。

Research purposes: Foundation pit excavations have additional impact on adjacent structures, and it will reduce the bearing capacity of adjacent foundation. Considering that the influence of seepage is usually ignored in the study of bearing capacity of strip footing adjacent to foundation pit, the bearing capacity of strip footing adjacent to foundation pit subjected to seepage is calculated by the finite element limit analysis method, and the influence of strip footing load, anchor bolt, groundwater level and filling strength on the bearing capacity of adjacent foundation pit is studied. Research conclusions:(1) It was found that the calculation values from the finite element limit analysis method are close to those from the traditional elastic-plastic finite element method and the limit equilibrium method, however, the calculation speed of the former was faster.(2) When the width of strip footing is large and its distance to the foundation pit is relatively close, the seepage will significantly reduce the bearing capacity of the strip footing adjacent to the foundation pit as compared to that without seepage.(3) The bearing capacity of the strip footing adjacent to the foundation pit decreases first and then increases slowly with the increase of the water head difference between the inside and outside of the foundation pit.(4) The bearing capacity of strip footing adjacent to foundation pit can be effectively improved by anchors in the upper part of the foundation pit.(5) The bearing capacity increases approximately linearly with the soil strength.(6) The research results can be used as a reference for design of structures adjacent to foundation pits.