Attenuation Law of Stress Waves in Cracked Rock Mass under Different Confining Pressures

Abstract

Through theoretical analysis and indoor model tests, this paper explores the attenuation law of stress waves in the intact confined rock mass and cracked rock mass under different confining pressures, especially the relationship between the stress attenuation coefficient, crack width, and crack angle, respectively. The tests were carried out on a triaxial test system for deep rock mass, which supports both static and dynamic loading. The research results show that the physical attenuation of the stress wave in the intact rock mass first decreases and then increases with the increase of the confining pressure and decreases with the increase of crack width. The attenuation coefficient of stress waves in the cracked rock mass depends on the crack angle and crack width. Specifically, the coefficient is negatively correlated with crack width; under no confining pressure, the coefficient decreases with the increase of the crack angle; when the confining pressure is on a moderate level, the coefficient increases with the crack angle; when the confining pressure exceeds the uniaxial intensity by 34%, the coefficient decreases again with the increase of the crack angle. The theoretical propagation equation of stress waves at the crack, which was derived from the propagation attenuation mechanism of stress waves in the cracked rock mass, was proved feasible through the comparison against the experimental results.

Stress wave propagation in different number of fissured rock mass based on nonlinear analysis

“…The model casting was carried out layer by layer so as to fix the fissure and plant the strain brick; the vibration stirrer was used in the pouring process to ensure that the density of the model was uniform and to reduce the influence of interface delamination on the wave propagation. The effectiveness of stress waves tested by such tests has been verified in previous studies [13].…”

“…where A is the peak stress after passing through the cracks. When the stress wave P-wave propagates through multiple fissures, assume the rock materials between the fissures are linear elastic materials, then the P-wave satisfies the time-shifting function [13]:…”

Fluctuation Characteristic Test of Oblique Stress Waves in Infilled Jointed Rock and Study of the Analytic Method

“…Stress wave attenuation occurs when the joint filling reaches a certain thickness and becomes nonnegligible. In addition, it can cause the attenuation of wave propagation velocity and energy which can further affect the stability of rock mass [1][2][3]. e incidence condition of stress waves at any angle can be more complicated than that of the vertical incidence condition in the rock joint.…”