基坑开挖对临近地基极限承载的影响性状数值分析

采用弹塑性有限元分析方法,分析了悬臂式排桩支护的基坑开挖对邻近地基条形基础下极限承载力的影响性状。主要考虑了在基坑开挖深度、荷载与基坑的距离、荷载宽度、支护刚度等因素的影响下地基极限承载力的减损性状。研究表明,基坑开挖深度H较浅时,对地基极限承载力P_u的影响较小,P_u随H的增大略有降低,随着开挖深度的增加,H对P_u值的影响显著增大,且P_u值显著降低;当L/H≤2时,荷载与基坑的距离L对地基极限承载力P_u的影响很大,地基极限承载力P_u随L的减小而显著减小,当L/H>3时,L的影响逐渐减小,且P_u逐渐趋近于无基坑开挖时的值;P_u随地基荷载作用宽度B的增大而呈线性增大;支护桩的位移越小,P_u值越接近无基坑开挖时的地基极限承载力。

Numerical Analysis of the Effect of Excavation on Bearing Capacity of Neighboring Soils

Using an elastic-plastic finite element method,the effect of excavation on bearing capacity of neighboring soils under a rigid strip footing was investigated to analyze the influence of such factors as ex- cavating depth,distance between load and excavated pit,load width,un-drained shear strength of soil and bracing stiffness.It shows that the un-drained shear strength of soil,the load position and excavating depth all have great effects on the ultimate bearing capacity,but the influence of bracing stiffness is rela- tively small.The ultimate bearing capacity decreases rapidly with the increasing of excavating depth and shortening of the distance between the rigid strip footing and excavation.And the uhimate bearing capaci- ty increases linearly with the un-drained shear strength of soil and load position.The bracing stiffness has little influence on the uhimate bearing capacity.