考虑互层状岩体接触状态的地下洞室围岩稳定分析

Stability Analysis of Surrounding Rock of Underground Caverns Considering Contact State of Interbedded Layered Rock Mass

层间剪切、挤压破碎带是影响互层状岩体地下洞室围岩稳定的重要因素.针对互层状岩体层间剪切、挤压破坏问题,引入界面单元模型模拟其接触特性.在此基础之上,对该接触面模型算法进行改进,针对接触面边界上节点可能存在的接触状态:黏结、滑移、张开和嵌入,建立了相应的接触状态判别准则和修正迭代算法,可以有效模拟互层状岩体层间非线性滑移破坏问题.将本文模型应用于巴基斯坦阿扎德帕坦水电站地下厂房围岩稳定性分析中,对比横观各向同性模型计算结果,表明考虑接触后在层间过渡处应力和位移呈现非连续性变化,且量值增大;层间出现了错动位移,在主厂房边墙侧中下部较为明显.

The interlayer shearing and crushing fracture zone are the key factors affecting the stability of surrounding rock of underground caverns in interbedded layered rock mass.For the problem of the interlayer shearing and crushing failure of interbedded layered rock mass,the interface element model was introduced to simulate the interlayer contact characteristics.Based on this,the contact model algorithm was improved.In view of the possible contact states for nodes on the boundary of the contact surface such as bonding contact,slipping contact,opening and embedding contact,the corresponding contact state criterion and modified iterative algorithm were established,which can effectively simulate the nonlinear slip damage between layers of interbedded layered rock mass.Then,the proposed model was applied to the stability calculation of the surrounding rock of underground powerhouse of Azad Patan Hydropower Station in Pakistan.Compared with the calculation results of the transverse isotropic model,the stress and displacement at the interlayer transition zone vary discontinuously and increase after considering the contact;dislocation displacement occurs between layers,which is more obvious in the middle and lower parts of the side wall of the main underground caverns.