Research on Zonal Disintegration Characteristics and Failure Mechanisms of Deep Tunnel in Jointed Rock Mass with Strength Reduction Method

Abstract

To understand the fracture features of zonal disintegration and reveal the failure mechanisms of circle tunnels excavated in deep jointed rock masses, a series of three-dimensional heterogeneous models considering varying joint dip angles are established. The strength reduction method is embedded in the RFPA method to achieve the gradual fracture process, macro failure mode and safety factor, and to reproduce the characteristic fracture phenomenon of deep rock masses, i.e., zonal disintegration. The mechanical mechanisms and acoustic emission energy of surrounding rocks during the different stages of the whole formation process of zonal disintegration affected by different-dip-angle joints and randomly distributed joints are further discussed. The results demonstrate that the zonal disintegration process is induced by the stress redistribution, which is significantly different from the formation mechanism of traditional surrounding rock loose zone; the dip angle of joint set has a great influence on the stress buildup, stress shadow and stress transfer as well as the failure mode of surrounding rock mass; the existence of parallel and random joints lead the newly formed cracks near the tunnel surface to developing along their strikes; the random joints make the zonal disintegration pattern much more complex and affected by the regional joint composition. These will greatly improve our understanding of the zonal disintegration in deep engineering.

Numerical Investigation on Anisotropy and Shape Effect of Mechanical Properties of Columnar Jointed Basalts Containing Transverse Joints

“…Additionally, the effectiveness of RFPA has been verified by many benchmarks (Xu et al 2021;Wang et al 2022). Meanwhile, RFPA has been applied in the stability assessment (Chen et al 2022;Gong et al 2022a), failure mechanism (Zhou et al 2018;Gong et al 2022b) and instability precursor (Liu et al 2017;Zhang et al 2021) of rock mass.…”

Anisotropy and microcrack-induced failure precursor of shales under dynamic splitting

“…To further reveal the mechanical mechanism underlying the failure characteristics of shales, the RFPA method (Gong et al 2019a;2019b;Chen et al 2022) and the digital image processing (DIP) (Feng et al 2022;Gong et al 2022;Wang et al 2022a) were combined to capture the stress/strain variation and reproduce the gradual failure process of shale discs numerically. Considering that the shales, as a kind of heterogeneous materials, contain various granular media, holes, micro-cracks and other defects, their mechanical behaviours are closely related to the inner meso-structure, such as stress distribution, crack propagation, damage evolution and failure mode.…”

Research on Fault Activation and Its Influencing Factors on the Barrier Effect of Rock Mass Movement Induced by Mining

“…Some scholars have studied fault activation through indoor experiments, Ohno et al [22] conducted injection tests and repeated packer tests on siliceous mudstone faults, which can effectively evaluate the sensitivity of fault hydraulic fracturing to fault activation. Chen and Gong et al [23][24][25] used acoustic emission technology to unite RFPA software to simulate and analyze the failure process of deep rock joints, and revealed the failure mechanism of deep jointed rock mass during excavation. Mngadi and Nguyen et al [26,27] carried out friction experiments of different groups on rocks from deep mining in high-stress areas, and described the propagation process of the fracture along the underground brittle shear zone, which is of great significance to the study of rockburst.…”