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为研究隧洞掘进机(tunnel boring machine,TBM)掘进下隧洞围岩的损伤特征,选取南水北调西线工程为背景工程,针对隧洞围岩TBM掘进后的损伤进行了系统的研究与分析。根据板岩在室内试验中表现出来的脆性和屈服后强度特性,提出了以黏聚力弱化-摩擦角强化(cohesion weakening and frictional strengthening,CWFS)脆性模型为基础考虑岩体屈服后损伤的本构模型,通过VC++编译dll动态链接库,并将其植入FLAC3D程序中。应用神经网络和遗传方法等优化算法对本构模型中的参数进行了反演分析,并以室内三轴压缩试验为依据,对该本构模型进行了验证。结果表明,提出的考虑损伤的CWFS模型可以较好地反映板岩的弹性特征、屈服后的强化特征、脆性破坏特征和破坏后残余强度特征。以该模型为基础,模拟了南水北调西线隧洞在TBM掘进条件下隧洞围岩的变形特性、应力发展规律及其损伤演化特征,并与基于Mohr-Coulomb本构关系的计算结果进行了对比分析。提出的考虑损伤的CWFS模型能更好地反映隧洞掘进后围岩损伤特征,即损伤沿着弱势区域发展的规律。
In order to study the damage characteristics of surrounding rock of tunnel boring machine (TBM) tunneling, the project of West Route of South-North Water Diversion Project is selected as the background project, and the damage of tunnel surrounding rock after TBM tunneling is systematically studied and analyzed. According to the brittleness and post-yield strength characteristics of slate in laboratory tests, the constitutive model of post-yield damage of rock mass based on brittleness-cohesion weakening and frictional strengthening (CWFS) brittleness model is proposed Model, compile dll dynamic link library through VC ++, and implant it into FLAC3D program. The parameters of the constitutive model were inversely analyzed by using optimization algorithms such as neural network and genetic method. The constitutive model was verified by the indoor triaxial compression test. The results show that the proposed CWFS model can well reflect the elastic characteristics of slate, the strengthening characteristics after yielding, the brittle failure characteristics and the residual strength characteristics after failure. Based on this model, the deformation characteristics, stress development rules and damage evolution characteristics of the tunnel surrounding the tunnel under TBM conditions are simulated and compared with the results based on the Mohr-Coulomb constitutive equation. The proposed CWFS model considering damage can better reflect the characteristics of surrounding rock damage after tunneling, which is the rule of damage development along the weak area.