基于非线性M-C准则的圆形基础下伏土洞抗冲切破坏研究

Punching analysis of soil under circular foundation based on nonlinear M-C criterion

针对土体材料特点,引入非线性Mohr-Coulomb准则及相关流动法则,构建圆形刚性基础下伏土洞冲切破坏模式。采用极限分析上限法推导出其极限承载力的计算公式,得出参数任意组合条件下圆形刚性基础下伏土洞冲切极限承载力。利用Plaxis 3D软件建模分析,并与理论解进行对比,验证本文方法的有效性。研究结果表明:非线性系数m对极限承载力的影响较大,在其他参数条件一定的情况下,极限承载力与m呈非线性负相关,且趋于稳定。极限承载力随土体初始黏聚力C_0,顶板厚度以及刚性基础宽度的增大而增大,随土体重度、土体抗拉强度的增大而减小。

The nonlinear Mohr-Coulomb failure criterion and the associated flow rule have been introduced according to the characteristics of soil mass,and then the punching failure mechanism of the soil with an underlying circular rigid foundation was constructed.Then the calculation formula of the ultimate bearing capacity was established using limit analysis method.Furthermore,the ultimate bearing capacity of the soil with an underlying circular rigid foundation was obtained in the condition of arbitrary combination of parameters.The Plaxis 3D software was used to analyze,and the numerical results were in agreement with the theoretical solutions,which verified the validity of the proposed method.The influence of parameters on ultimate bearing capacity was also analyzed,and the results shows that the influence of the nonlinear coefficient m on the ultimate bearing capacity is obvious,and that the ultimate bearing capacity decreases with the increase of m,and the decreasing trend tends to be gentle with given parameters,.The ultimate bearing capacity increases with the C0 of initial cohesive force of soil,the roof thickness and the rigidity foundation width,and decreases with the increase of soil weight and the increase of soil tensile strength.