The fault fracture zone is vital to the stability of the surrounding rock of tunnels in geological engineering. In this study, a three-dimensional numerical model was established for Wuzhuling Tunnel of Zhuji-Yongjia Highway in Zhejiang Province, China. The dynamic processes of tunnel excavation were simulated through the fault fracture zone. The deforming performance and stress distribution of surrounding rock were investigated. Moreover, the stability of surrounding rock in tunnels was analyzed with consideration of the slope angle and the width of the fault. The simulation results indicate that the fault fracture zone in the tunnel can reduce the stability of surrounding rock. The slope angle and the width of the fault all have obvious influences on the stability of surrounding rock in tunnels. Furthermore, the collapse processes of a tunnel in the construction steps were investigated in a laboratory model. Reasonable agreements can be obtained to validate the model presented here and the simul...

In order to evaluate the risk level of water inrush caused by karst cave accurately and effectively, a novel quantitative assessment model was established based on the reliability theory and genetic algorithm-back propagation (GA-BP) neural network. First, the reliability theory and the calculation formula of the minimum safe thickness were used to calculate the water inrush probability. Second, the GA-BP neural network was applied to predict the disaster consequence caused by water inrush. Six factors, including water pressure, hydraulic supply, type of gap, filling situation, degree of water enrichment and reserves of cave, were selected as the input layer of the neural network. The disaster consequence was selected as the output layer. Similar projects were screened to obtain statistical information for indices, and the Normand function in MATLAB was used to transform the information into quantitative data. Finally, the model was established by combining the probability and disaster consequence of water inrush. The 602cave in Yesanguan tunnel was taken as an engineering sample to verify the feasibility of the novel model. The obtained results showed that the proposed model is comprehensive and accurate in quantitative assessment, which has good application prospects in engineering.

Rock-like materials generally manifest both strain-softening and pressure-dependent effects. The critical plastic strain corresponding to the residual state also increases with the confining pressure. In this case, all of the mechanical property parameters are the functions of plastic strain and confining pressure. The elastoplastic coupling strain-softening model (EPCSS) is established by dividing the elastic and plastic surrounding rock of circular openings into m and n annuli, respectively. When the range of each annulus is significantly small, the surrounding rock can be considered as isotropic and uniform. Then, the elastoplastic coupling analytical solutions can be derived by representing the material properties of each annulus with the corresponding value at each annulus’s outer radius for both Mohr–Coulomb (M-C) and Hoek–Brown (H-B) rock masses, respectively. Based on the continuum conditions of adjacent annuli, the equations for determining the radius of each annulus were established. Finally, the solutions were validated by strain-softening rock mass, and examples of EPCSS rock mass were further studied.