Stress wave propagation and incompatible deformation mechanisms in rock discontinuity interfaces in deep‐buried tunnels

Abstract

Complex weak structural planes and fault zones induce significant heterogeneity, discontinuity, and nonlinear characteristics of a rock mass. When an earthquake occurs, these characteristics lead to extremely complex seismic wave propagation and vibrational behaviors and thus pose a huge threat to the safety and stability of deep buried tunnels. To investigate the wave propagation in a rock mass with different structural planes and fault zones, this study first introduced the theory of elastic wave propagation and elastodynamic principles and used the Zoeppritz equation to describe wave field decomposition and develop a seismic wave response model accordingly. Then, a physical wave propagation model was constructed to investigate seismic waves passing through a fault, and dynamic damage was analyzed by using shaking table tests. Finally, stress wave attenuation and dynamic incompatible deformation mechanisms in a rock mass with fault zones were explored. The results indicate that under the action of weak structural planes, stress waves appear as a complex wave field decomposition phenomenon. When a stress wave spreads to a weak structural plane, its scattering may transform into a tensile wave, generating tensile stress and destabilizing the rock mass; wave dynamic energy is absorbed by a low-strength rock through wave scattering, which significantly weakens the seismic load. Wave propagation accelerates the initiation and expansion of internal defects in the rock mass and leads to a dynamic incompatible deformation. This is one of the main causes for large deformation and even instability within rock masses. These findings provide an important reference and guide with respect to stability analysis of rock mass with weak structural planes and fault zones.

Experimental Study on Axial Stress and Hammer Impacting Energy of Offshore Standard Penetration Test

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Investigation of the anisotropic mechanical response of layered shales

“…Generally, metamorphic rocks (e.g., slate, gneiss and phyllite) and sedimentary rocks (e.g., shale) are sensitive to the structural anisotropy and behave differently along various directions. Actually, the influence of the pre‐existing discontinuities on the mechanical behaviour of shales cannot be ignored 1,2 . In recent years, some researchers have investigated the anisotropic properties of layered rock masses under compression.…”

“…Actually, the influence of the pre-existing discontinuities on the mechanical behaviour of shales cannot be ignored. 1,2 In recent years, some researchers have investigated the anisotropic properties of layered rock masses under compression. For example, Wang et al 3 proposed an elastoplastic model for layered rock mass that exhibited hybrid initial and stress-induced anisotropy.…”