中文摘要：

岩溶区基础下伏空洞时,其地基承载力计算变得十分复杂。为考虑多种因素对地基承载力的影响,基于上限分析有限元法对岩溶区地基极限承载力进行数值模拟分析。首先,提出合理的计算假定简化,建立可考虑多因素影响的地基计算模型;其次,利用Matlab平台编制上限分析有限元程序,对地基承载力作数值计算,得到各种工况的地基极限承载力上限解,并绘制相应的分析图表;再次,分析地下空洞埋置深度、洞径和岩土体内摩擦角对地基极限承载力的影响规律;最后,通过算例分析验证本文方法的合理性。研究结果表明：地基极限承载力随D/B（径宽比）增大而减小,随H/B（深宽比）和φ增大而增大,且φ值越大H/B和D/B对地基极限承载力影响越显著;岩溶区地层中空洞存在一个影响地基极限承载力的临界埋置深度,该临界埋置深度受D/B和φ影响。

英文摘要：

Under the influence of underlying void the ultimate bearing capacity of foundation in karst area become very complexity.In order to consider multiple impact factors,based on the finite element upper bound method to numerical simulation analysis of the foundation bearing capacity in karst areas.Firstly,some reasonable assumption was made to simplify the problem,a foundation model was established to consider multi-factor.Secondly,program compiled in Matlab for numerical compute to the bearing capacity of foundation,the upper bound solution to the ultimate bearing capacity of the foundation was obtained,and draw corresponding analysis chart.Further,focus on discussion under the difference void＇s depths,diameter and soil internal friction angle φ the variation rule of ultimate bearing capacity.Finally,the reasonableness of the proposed method was verified by an engineering example.The results show that：ultimate bearing capacity of foundation decreasing when D / B（diameter width ratio） increased,and increasing with H / B（depth width ratio） and φ arise.H / B and D / B affected ultimate bearing capacity more obvious when φ is larger.There is a critical buried depth of voids in the ground,which influenced the ultimate bearing capacity of foundation.The critical buried depth of voids is relative to D / B and φ.