大型地下洞室高边墙的拉应变准则研究

高地应力等复杂环境下大跨度地下洞室群开挖容易诱发高边墙的脆性拉裂破坏，在Mohr-Coulomb准则基础之上，基于拉应变准则，提出大型地下厂房高边墙破坏的复合拉剪屈服准则。根据弹塑性理论，张拉和剪切屈服分别采用相关联和非相关联的塑性流动法则，详细推导了该准则在有限差分法中的计算格式，并对张拉和剪切屈服面的应力空间进行了分界。利用C语言程序编写的动态链接库文件，实现了该准则在通用软件的科学仿真计算。以高应力地区的拉西瓦水电站地下厂房为工程实例，与FLAC3D自带的拉剪屈服准则相比，基于拉应变准则的计算结果表明，大跨度高边墙拉破坏明显，塑性区以及应力松弛区的面积更小，能合理描述硬岩高边墙的脆性拉裂破坏特征。大型硬岩地下洞室群的计算分析验证了该准则的合理性和实用性

Study of tensile strain criterion of high sidewall in large underground caverns

The excavation of large underground caverns easily induces brittle cracking failure of high sidewall under high ground stress and other complex condition. Based on Mohr-Coulomb criterion and tensile strain criterion, a new composite tensile-shear yield criterion of high sidewall for large underground powerhouse was proposed. At first, according to the elastoplastic theory, associated and non-associated plastic flow rule were adopted independently for tension and shear yield. The calculation formula of this rule is deduced in detail in the finite difference method; and the dividing boundary of tensile and shear yield surface in stress space is determined. Then dynamic link library of the software is programmed adopting the C language; and the criterion can be used in the general software. Finally, taking the Lashiwa hydropower station located in the high geostress region for example, compared to FLAC3D own tensile-shear yield criterion, the results show that the tensile failure of high sidewall is obvious; and plastic zone and stress relaxation area is smaller by considering the tensile strain yield criterion; the proposed criterion can describe brittle cracking failure features of hard rock for high sidewall. Calculation of large hard rock underground caverns proves that the proposed criterion is reasonable.