基于非线性破坏准则的临坡地基承载力上限分析

Upper bound solution for ultimate bearing capacity of ground adjacent to slope based on nonlinear failure criterion

临坡地基承载能力的确定分析已成为地基设计理论中一个重要研究课题。针对现有地基承载力分析方法大多基于线性Mohr-Coulomb破坏准则。考虑岩土材料破坏的非线性特性,采用非线性破坏准则和多切线法,引入极限分析上限理论,根据临坡条形基础地基破坏模式的非对称性特点,构建出临坡条形基础地基单侧刚性多滑块破坏模型及相应运动允许速度场。在此基础上,利用序列二次规划非线性优化算法,建立临坡条形基础地基极限承载力的确定方法。最后,通过工程实例计算,并与已有研究方法计算结果进行对比分析。结果表明,非线性参数对临坡地基承载力有着重要影响,采用多切线法处理非线性材料强度准则问题理论上更严密,上限解更优,验证了该方法的可行性与合理性。

The determination of ultimate bearing capacity of foundation near slope is an important subject for foundation design. Bearing capacity of ground is conventionally calculated using linear Mohr-Coulomb failure criterion. However, measured data show that the strength envelopes of geomaterialS are nonlinear. In this paper, the upper bound theorem of limit analysis with nonlinear failure criterion and a multi-tangential technique were employed to evaluate the bearing capacity of strip footings adjacent to slope. The unilateral rigid blocks sliding mode of strip footings adjacent to slope was considered according to the characteristics of the asymmetry failure mode. The velocity comparability and plastic flow rule satisfy the corresponding velocity field. A mobile permissible velocity field and the ultimate bearing capacity calculation formula of strip footings adjacent to slope were developed. A new method of determining ultimate bearing capacity of strip footings near slope was implemented using sequential quadratic programming optimization algorithm. The proposed method shows superior to other existing methods. The feasibility, rationality and universal applicability of the approach verified by comparison and analysis with current research results. Nonlinear failure parameter significantly impacts the bearing capacity. The rigorous multi-tangential technique method optimum calculated results.