Numerical solution for circular tunnel excavated in strain-softening rock masses considering damaged zone

Abstract

Despite the extensive investigation on the stress and displacement distributions in tunnels, few have considered the influences of the damaged zone around a tunnel on the strength and stiffness parameters of the surrounding rock, including the gradual variation in the damaged factor D and dimensionless damaged radius $$\rho^{{\text{d}}}$$ ρ d , under the effect of excavation disturbance. In this paper, a numerical solution is presented for the stresses and displacement of a circular tunnel excavated in a Hoek–Brown rock mass considering the progressive destruction of the damaged zone. First, the results obtained using the proposed algorithm are compared with those obtained using other numerical solutions, demonstrating a high degree of accuracy through some examples. Second, the influences of the damaged factor $$D$$ D and dimensionless damaged radius $$\rho^{d}$$ ρ d on the stresses, radial displacement, plastic radii, and ground response curve are investigated. The results show that, as the damaged factor D increases, the radial displacement and plastic radius increase, whereas the tangential stress decreases. Both the plastic radius and displacement decrease with decreasing $$\rho^{{\text{d}}}$$ ρ d . This shows that the damaged factor D has a significant effect on tunnel convergence.

Analytical solutions for cavity contraction in strain-softening materials with linear or exponential strength decay

“…The contraction of cavities excavated in strain-softening rock masses has so far been studied using analytical, semi-analytical and numerical methods, which can generally be categorized into two groups based on their treatment of strain within the plastic zone: rigorous methods utilizing incremental plasticity and simplified methods. Recent works and comprehensive reviews of the state of the art can be found in 1 – 11 .…”

Evaluation of deformation characteristics of brittle rocks beyond the limit of strength in the mode of uniaxial servohydraulic loading

“…For example, when using the RS2 (Rocscience) program, when developing an elastic-plastic model taking into account the Coulomb -Mohr criterion with residual strength, data from the passport of the residual strength of rocks are required [23,24]. The frequently used Hook -Brown strength criterion additionally requires workings mapping data to assess the disturbance of the rock mass [25][26][27]. Therefore, the necessary initial data can be obtained only as a result of laboratory tests and field studies.…”