进一步分析了第Ⅰ部分[1]提出的泥岩渗流-应力耦合蠕变损伤模型。在连续损伤力学理论和比奥(Biot)理论的基础上,导出了考虑渗流-应力-损伤耦合的蠕变损伤有限元格式,建立了弹性预测、塑性修正、损伤修正-渗透系数修正的数值分析框架,编制了非线性有限元分析程序。根据监测的衬砌长期变形数据,采用优化反分析法获得了蠕变损伤模型中的待定参数,并应用于比利时核废料库施工过程中泥岩巷道围岩渗流-应力耦合过程、损伤演化以及长期稳定性分析,研究结果表明,泥岩开挖后渗透性明显增大,约为原岩的120倍,蠕变效应导致泥岩裂隙和渗透性自愈合,约3.5年后渗透性基本恢复到原岩的数量级,围岩中部的蠕变明显大于顶部和底部。研究成果对软岩隧洞长期稳定性的预测与预报具有一定的参考意义。
Further analysis is performed on hydro-mechanical-damage coupled creep constitutive model of mudstone proposed by authors in part one.Based on the continuum damage mechanics and Biot theory,the finite element equations of creep damage model are derived by considering the hydro-mechanical-damage coupling.The four-step numerical framework,i.e.,elastic predictor-plastic corrector-damage corrector-permeability corrector,is provided.A nonlinear finite element analysis program is developed by the above algorithm.Based on the in-situ monitoring results of lining deformation for about 20 years,the unknown parameters of mudstone are acquired by the method of displacement back analysis.Considering the actual case of the construction of the Test Drift of radioactive waste disposal in the deep Boom mudstone formation in Belgium,the hydro-mechanical coupling process,the evolution of damage and the long term stability of the surrounding rock are studied by the proposed models.The results show that the permeability of excavation damaged zone is 120 times than that of the original mudstone after excavation.Because of the self-healing of fractures,the permeability of excavation damaged zone changes obviously and tends to self-heal with time because of the stress-water action.About 3.5 years later,the permeability of the surrounding rock is near original mudstone.The creep damage increases rapidly in the early stage and tends to stabilize gradually with time.Damage of middle part is larger than that of bottom and top part of the surrounding rock.The study can be used for predicting the long-term stability of tunnel engineering.