层状岩体地下洞室破坏模式数值模型及验证

Numerical model and validation of failure mode for underground caverns in layered rock mass

基于层面法向局部坐标系中的横观各向同性弹性本构模型,根据层面产状方位角,推导出整体坐标系中弹性应力的转换方法。针对层状岩体的各向异性特征,将岩体的破坏模式细分为5种,分别对每一种破坏模式建立各自的判别函数和屈服准则,根据塑性流动正交法则推导出相应的应力修正迭代计算方法。通过单轴、三轴压缩数值试验,对层状岩体的强度和变形性质进行研究,分析层面倾角和围压对层状岩体力学行为的影响。将所建模型与FLAC3D自带的横观各向同性弹性模型以及遍布节理模型进行对比,验证模型的正确性及精度。同时,将模型应用于三向等压理想圆形隧洞的开挖计算中,分析层状岩体破坏方式受层面方位角影响的变化规律,分析结果表明层面对围岩破坏模式和塑性区扩展方向起到了控制作用。

Based on the transversely isotropic elastic constitutive model in the local coordinate system of bedding plane,according to the occurrence of layer,the stress conversion method from the global to local coordinate system is derived.For the anisotropic characteristics of the layered rock mass,the failure mode is subdivided into five kinds,for which the discrimination function,yield criterion and corresponding stress modified iteration calculation are respectively established according to plastic flow rule.A second development is carried out with VC++ programming language to generate a dynamic link library DLL file called by FLAC3Dmain program at any time.The strength and deformation properties of layered rock mass are studied through uniaxial and triaxial compression numerical experiments which indicate that the inclination angle and the confining pressure have an important influence on mechanical behaviors of layered rock mass.Compared with transversely isotropic elastic model as well as ubiquitous-joint model in FLAC3D,the correctness and accuracy of the new model are verified.Finally,the new model is applied to the calculation of an ideal circular tunnel in triaxial equal pressure in which the variation rule of failure modes of the layered rock mass influenced by the azimuth is analyzed.The results indicate that the altitude of bedding planes of layered rock mass is playing a control role to deformation distribution,failure mode and the propagation direction of plastic zones.