基于双剪统一强度理论的地基承载力计算方法研究  

Research on calculation method of foundation bearing capacity based on double shear unified strength theory

作　　者：杨继强 孙昕 崔向东 YANG Jiqiang;SUN Xin;CUI Xiangdong(Key Laboratory of Highway Engineering in Special Areas,Chang’an University,Xi’an,Shaarixi 710064,China)

机构地区：[1]长安大学特殊地区公路工程教育部重点实验室,陕西西安710064

出　　处：《岩石力学与工程学报》2021年第9期1923-1932,共10页Chinese Journal of Rock Mechanics and Engineering

摘　　要：为了解决传统地基承载力公式中没有考虑中主应力影响的问题,将地基土达到极限平衡状态时的屈服准则由原来的Mohr-Coulomb屈服准则替换为考虑中主应力作用的双剪统一强度理论。采用数学推导和计算机编程的方法提出计算地基承载力的参数代换法和理论推导法(包括显式理论推导法和隐式理论推导法)。首先,推导以压为正条件下用抗剪强度参数表示的双剪屈服函数表达式。然后针对参数代换法提出它的适用条件和代换步骤,并在平面应变条件下推导统一内摩擦角和统一黏聚力,针对理论推导法提出它的适用条件,并采用MATLAB软件将隐式理论推导法的计算步骤封装成F-C函数;最后,分别采用参数代换法和理论推导法对一典型条形浅基础进行地基承载力计算。结果表明,参数代换法和理论推导法计算得到的地基承载力值是一致的,且地基承载力随着中主应力影响系数的增大而增大。这说明针对地基承载力计算的参数代换法和理论推导法都是正确的,且中主应力对地基承载力的贡献不可忽略,基于双剪统一强度理论计算得到的地基承载力更为合理。In order to solve the problem that the intermediate principal stress is not considered in the traditional foundation bearing capacity formula,the Mohr-Coulomb yield criterion describing the limit equilibrium state of foundation soils is replaced with the double shear unified strength theory considering the action of the intermediate principal stress.Using mathematical derivation and computer programming methods,the parameter substitution method and theoretical derivation methods(including explicit and implicit theory derivation methods)for calculating the foundation bearing capacity are proposed.Firstly,the expression of the double shear yield function expressed by the shear strength parameter is derived by assuming compression being positive.Then,the applicable condition and substitution steps of the parameter substitution method are put forward,and the unified internal friction angle and unified cohesion under plane strain condition are derived.The applicable conditions of the theoretical derivation methods are also proposed,and the calculation steps of the implicit theory derivation method are encapsulated into F-C functions using MATLAB software.Finally,the parameter substitution method and theoretical derivation method are used to calculate the foundation bearing capacity of a typical shallow strip foundation.The results show that the foundation bearing capacity calculated by the parameter substitution method is consistent with that by the theoretical derivation method,and the foundation bearing capacity increases with increasing the influence coefficient of the intermediate principal stress.To sum up,both the parameter substitution method and the theoretical derivation method are applicable for the calculation of the foundation bearing capacity,the contribution of the intermediate principal stress to the foundation bearing capacity cannot be ignored,and the foundation bearing capacity calculated based on the twin shear unified strength theory is more reasonable.

关 键 词：地基基础 双剪统一强度理论 临塑荷载 临界荷载 统一内摩擦角 统一黏聚力 

分 类 号：TU47[建筑科学—结构工程]