Abstract

Due to the excavation or reinforcement of tunnels, the properties of the rock mass close to tunnels can be significantly changed. To account this issue, a closed-form solution is presented to determine the induced stresses and deformations with consideration of the effects of the altered zone around a circular tunnel and of the self-weight of different zones. For this purpose, the Mohr–Coulomb criterion and the elastic–brittle–plastic model are assigned to both the altered zone and the initial rock mass. Due to the different properties of these zones, the plastic zone can be initiated from the altered zone, the initial rock mass, or both of them simultaneously. By gradually decreasing the internal support pressure, it can be expected that the stresses satisfy the failure criterion. Investigating possible conditions, it can be seen that six different cases can exist. These cases were analysed, and the code of which was written in the MATLAB software. After verifying the proposed procedure with the existing analytical methods, a parametric study was conducted. The results show that neither of the damaged zone nor the reinforcement zone can be neglected, and the propagation of the plastic radii must be considered.

摘要

由于隧道开挖或加固，隧道附近岩体的性质会发生显着变化。为了解决这个问题，考虑到圆形隧道周围蚀变区和不同区域自重的影响，提出了一种封闭形式的解决方案来确定诱导应力和变形。为此，Mohr-Coulomb 准则和弹脆塑性模型被分配给蚀变带和初始岩体。由于这些带的性质不同，塑性带可以从蚀变带、初始岩体或两者同时开始。通过逐渐降低内部支撑压力，可以预期应力满足失效准则。调查可能的条件，可以看出，可以存在六种不同的情况。对这些案例进行了分析，并在MATLAB软件中编写了代码。在用现有的分析方法验证了所提出的程序后，进行了参数研究。结果表明，无论是损伤区还是加固区都不能忽略，必须考虑塑性半径的扩展。