在变形进入到塑性阶段之后,隧道岩体中会产生显著的能量耗散和自我组织现象,岩体粒子之间的长程相互作用明显。为此需要在岩体模型中加入内变量梯度项。作为额外的内变量,引入有效塑性应变梯度这一新变量。利用虚功原理得到岩体的平衡方程、边界条件。利用Clausius-Duhem不等式获得岩体内变量演化方程。对于圆形深部隧道,由上述理论得到有效塑性应变的支配方程和边界条件,并利用岩体理想脆性模型求得支配方程的解。该解能够描述深部隧道围岩的分区破裂现象。
In plastic deformation regime, energy dissipation and self-organization phenomenon take place in rock masses surrounding tunnels, and the long-range interaction between rock particles becomes significant. Therefore, the term of internal variable gradient should be added to the constitutive model of rock masses. Gradient of effective plastic strain is introduced as an additional internal variable. Equilibrium equations and boundary conditions are derived by using the virtual work principle. Evolutionary equations for internal variables of rock masses are obtained by using the Clausius-Duhem inequality. For circular deep tunnels, the governing equation for effective plastic strain is obtained from the above model. Solution to the governing equation for ideal brittle model of rock masses is achieved. The solution may describe zonal disintegration phenomenon very well.