Study of the Failure Mechanism of Soft Rock Mining Roadways Based on Limit Analysis Theory

Abstract

To study the deformation and failure mechanisms of soft rock mining roadways, the 1506 return airway of Anyang Coal Mine is taken as the engineering background. Based on limit analysis theory, a failure model based on a rigid slider system is constructed to assess the failure of the soft rock surrounding a roadway. The formulas for calculating the self-weight power of the slider in the velocity discontinuity line of the rock surrounding the roadway, the work power of the surrounding rock pressure, and the energy dissipation rate of the velocity discontinuity line are derived, and the upper limit objective function of the velocity discontinuity line height is obtained. The failure characteristics and fracture evolution process of the surrounding rock under different mining stresses are analyzed by means of physical similarity simulations. The simulation results show that shear failure occurs first on the roadway side due to stress concentration. The fissures expand along the bottom angle of the roadway to the blind support area and the low-intensity support area. The cracks weaken the support strength of the angled anchor cable and bolt in the roadway shoulder. Under the action of roof pressure, the status of the rock mass inside and outside the shear slip zone changes from static to dynamic. This causes deformation and failure of the roadway roof, side, and floor.

Failure Mechanism and Structural Safety Assessment of the Primary Support Structure of Soft Rock Tunnel: A Case Study

“…Due to limited field engineering conditions, the amount of field test data is limited and the research scope involved is relatively limited [9,17,18]. The numerical calculation model derived from field tests can overcome the research difficulties of single field test conditions and the difficulty in obtaining refined structural data [5,[19][20][21]. However, in the past, when establishing support structure models for large deformation tunnels in soft rock, sprayed concrete and steel rib structures with significant differences in stiffness and physical and mechanical properties in the primary support structure were often equivalent to uniform structures, which makes the mechanical response of the support structure in the numerical model significantly different from the field situation, and it is also impossible to compare and analyze the mechanical response and damage mechanism of sprayed concrete and steel rib structures under different primary support combinations, and cannot provide precise guidance for engineering practice [22].…”

Research on the Failure Mechanism of Surrounding Rock in a Dynamic Pressure Roadway and Active and Passive Coordinated Support Technology

“…Rong et al [7] found that the stability of the surrounding rock and the large loose circle is often compromised under current support conditions, leading to significant deformation in the rock adjacent to roadways when subjected to dynamic pressure. According to the limit analysis theory, a roadway soft rock failure model was developed by Zhang et al [8], and they analyzed the fracture evolution process of surrounding rocks subjected to various mining stresses. Wang et al [9] developed a model to analyze the structure of the overlying rock and stress distribution in coal pillars within a goaf roadway subjected to dynamic pressure.…”