Abstract
Exploring the propagation of stress waves in rocks with preexisting discontinuities is of great importance to reveal rock and geological engineering problems, particularly dynamic disasters like earthquakes and rockbursts in underground coal mining. In this paper, six 3D models established with COMSOL Multiphysics are employed to explore the influence of two preexisting faults with different orientations on the propagation process of explosion‐induced stress waves and the reflection effect. Considering the propagation process of stress waves, the interactive effect between two different size faults is discussed. The results show that the dip angles of the preexisting fault and the differences of the elastic modulus, density, and Poisson’s ratio between faults and rocks have great influence on the distribution of stresses and strain‐energy density. Immediately after the stress wave induced by blasting arrived at preexisting fault A, a relatively high concentration of the strain‐energy density was observed at the last wave before passing through fault A. The presence of faults leads to the reflection of most of the blast energy. When the stress wave propagates across fault A, the strain energy stored in the stress wave becomes attenuated; thus, most strain energy was absorbed by the fault’s domain. Finally, the modeling results were implicated in Chaoyang Coal Mine to account for the distribution of the observed seismic events. This study has guiding significance for the attenuation law of stress waves passing through joint/fissure zones in geological engineering, earthquake engineering, and underground mining engineering.
Highlights
It was found that when the stress wave induced by blast loading initially arrived at the preexisting fault plane (fault A), a relatively high concentration of the strain energy density was observed at the last wave before passing through fault A. e presence of a fault leads to the reflection of most of the blast energy [27]
We explored the influence of two preexisting faults with different orientations on the propagation process of the explosioninduced stress wave and the reflection effect by building six 3D models using COMSOL Multiphysics
Some results were achieved which are as follows: (1) For a horizontal delamination, the maximum tensile and compressional stresses decreased with time, and a dislocated feature of the stress wave was observed in a triangular area along fault A due to the effects of natural vibration and/or absorption during the propagation process of the stress wave
Summary
Understanding stress wave propagation is of great significance to the constitutive relationship of rock mass, slope stability, earthquakes, and underground coal mining. ere is a large variety of artificial or natural cracks, gaps, various joints, faults, folds, and interlayers inside rocks, along which shear is more likely to occur and deformation is usually nonlinear [1]. ese structural planes have nonuniformities and discontinuities, and the cores of these structural planes are usually wet or filled with water [2], which can significantly reduce the strength of the rock mass and have an important influence on the propagation of stress waves in the rock mass [3,4,5,6,7,8]. Ere are many weak structural planes in rock mass, such as faults, joints, and fissures, which seriously hinder the propagation of stress waves and exacerbate the attenuation of stress wave energy. Xie et al [22] analyzed the influence of the angle between the dip direction of the joint and the stress wave on the propagation law of explosive stress waves. Erefore, it is necessary to further study the influence of the structural plane/ discontinuity in rock bodies (e.g., granite) on the propagation process of stress waves. A 3D model is established to explore the influence of two preexisting faults with different orientations on the propagation process of explosion-induced stress waves and the reflection effect. Ρ where λ is the first Lameparameter, μ is the shear modulus, and ρ is the density of the material through which the wave propagates
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