Mechanism of Time-Dependent Instability of Deep Soft-Rock Roadway and Crack-Filling Reinforcement Technology

Abstract

Soft broken surrounding rock exhibits obvious rheological properties and time-dependent weakening effects under the action of deep high-ground stress, leading to the increasingly prominent problem of sustained large deformation in deep roadways. In this study, with the II5 Rail Rise in Zhuxianzhuang Coal Mine as an example, the mechanism and control technology of time-dependent damage and instability in a deep soft-rock roadway were explored through a field observation and numerical simulation. The research results show that the range of the loose circle in the deep fractured surrounding rock can reach 3.0 m. The expansion of shallow and deep cracks causes the primary plastic deformation and secondary rheological deformation of the surrounding rock, with the rheological deformation rate increasing by 21.4% every 55 days on average, which ultimately induces the instability and failure of the surrounding rock. Based on the mechanism of roadway instability, a control technology of high-preload bolt + deep- and shallow-borehole crack filling was proposed. The technology reduces deformation and ensures the stability of the roadway surrounding rock by inhibiting the propagation of deep and shallow cracks and reinforcing the surrounding rock.

The Failure Law and Combined Support Technology of Roadways with Weak Surrounding Rock in Deep Wells

“…Zhan et al [7] suggested that the prominent contradiction between high stress and rock mass strength degradation was the intrinsic cause of nonlinear large deformation in deep soft rock roadways. Wu et al [8] pointed out that the main reason for the tunnel's serious damage is that the surrounding rock's rheological deformation intensifies the crack propagation inside the rock. Through numerical simulation, Zhu et al [9] believed that when the rock mass strength is low, the surrounding rock failure is mainly shear damage, and tensile damage is mainly concentrated at the bottom of the tunnel.…”