湿度扩散诱发的隧洞时效变形数值模拟研究

环境湿度在水敏感岩体中的扩散对隧洞等地下空间的变形起到至关重要的作用，不仅改变岩体的应力状态，还在很大程度上造成岩体物理力学性能的弱化，增强了岩体的时效变形特性。通过在数值模型中引入湿度扩散计算，并建立湿度扩散与岩体力学响应之间相互关系的描述，使得数值模型能模拟水敏感岩体受湿度影响的时效变形特征。针对具有支护系统的隧洞岩体在湿度扩散过程中的变形和应力特性的数值模拟研究表明：开挖初期，只有围岩表面的湿度产生变化，湿度引起的隧洞变形量也较小，但其变形速率却较大。随着湿度的进一步扩散，隧洞的变形总量增加，但变形速率逐渐降低，并最终得以收敛；数值计算再现了锚杆系统中的应力演化过程，其中拉应力的逐渐增大限制了围岩的部分变形；湿度在围岩中的扩散造成较大范围内围岩的强度降低，承载能力减弱，隧洞周边逐渐产生破坏。破坏的产生不仅引起局部应力集中，促使裂纹的进一步扩展，还有助于水分在围岩中的扩散。因此，湿度扩散和破坏（损伤）是一个相互影响的过程，也即湿度-应力-损伤耦合作用

Investigation on time-dependent deformation of tunnel induced by humidity diffusion

Humidity diffusion plays an important role on the deformation of water-sensitive rock in underground engineering. It is not only changed the stress state of rock mass, but also greatly weakened the physico-mechanical properties, which enhanced its time-dependent deformation. By introducing the humidity diffusion in numerical model and establishing the relationship between mechanical response of rock and the humidity diffusion, the numerical model is able to simulate the time-dependent deformation of water-sensitive rock. Numerical simulation of humidity diffusion in tunnel with support system shows that: humidity changes only occur on the surface of tunnel at the beginning of excavation, where the deformation induced by humidity is small but the deformation rate is great. With the humidity further diffusion, the deformation of tunnel increases but the deformation rate decreases, and eventually converges. Numerical simulation represents the stress evolution process of anchors, and the increase of tensile stress in anchors shows its effect on deformation of rock mass. The humidity diffusion reduces the strength of rock and induces rock failure. Failures not only cause the local stress concentration, but also enhance the humidity diffusion in rock mass. It is shown that the humidity diffusion and failures (damage) is an interactive process, namely the humidity-stress-damage coupling.