Abstract

The propagation of stress waves in filled jointed rocks involves two important influencing factors: transmission‐reflection phenomena and energy attenuation. In this paper, the split Hopkinson pressure bar (SHPB) test is used to shock the filled rock with joint angles of 0, 30, and 45° and the thickness of 4 mm and 10 mm, respectively, in three different velocities. The wave curves of the incident wave, reflected wave, and transmission are obtained. The effects of the filling angle and joint thickness on wave propagation are analyzed. Based on the propagation characteristics of stress waves in joints, the stress expression of oblique incident stress waves propagating in filling joints is derived, and the energy coefficient of transmission and reflection is calculated. The results show that the propagation of stress wave in filling joints is related to the impact rate. The larger the impact rate is, the larger the maximum voltage amplitude of the three waves is. And the increasing amplitude of the incident and reflected waves is larger than the transmitted wave; the greater the impact velocity is, the smaller the stress‐strain curve gap of the three dip joints is, and the fracture strength of the specimen decreases with the increase of the joint dip angle. The larger the joint dip angle is, the smaller the deformation of the rock‐like specimen is. The change of the transmission coefficient is related to the joint angle, and the larger joint angle weakens the influence of the joint width on the transmission of the transmitted wave; under each impact velocity, the theoretical and experimental stress peaks are approximately the same, and the transmission coefficient maintains a good consistency with the oblique incident angle.

Highlights

  • Rock is a natural geological body formed by the aggregation of minerals or cuttings under geological conditions

  • Stress wave attenuation occurs when the joint filling reaches a certain thickness and becomes nonnegligible. 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. erefore, profoundly studying the fluctuation characteristics and the dynamic properties of stress waves in the infilled obliquely jointed rock mass will have considerable theoretical significance and engineering application value

  • Ey were impacted under three different impact velocities, and the stress expression of the oblique stress wave propagated in the infilled joint was derived. e transmission energy coefficient was defined and calculated and compared with the test value. e following conclusions can be drawn: (1) e stress wave propagation in the infilled joint was affected by the impact velocity. e higher the impact velocity, the greater the maximum voltage amplitudes of the incident, reflected, and transmissive waves

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Summary

Introduction

Rock is a natural geological body formed by the aggregation of minerals or cuttings under geological conditions. Stress wave attenuation occurs when the joint filling reaches a certain thickness and becomes nonnegligible It can cause the attenuation of wave propagation velocity and energy which can further affect the stability of rock mass [1,2,3]. Erefore, profoundly studying the fluctuation characteristics and the dynamic properties of stress waves in the infilled obliquely jointed rock mass will have considerable theoretical significance and engineering application value. The authors carried out an experimental study of the propagation characteristics of stress waves in infilled joints under the impact load through the split Hopkinson pressure bar (SHPB). Che et al [18] investigated the influence of stress waves on the slope stability of a jointed rock mass through a numerical simulation and an experimental study. The related conclusions are obtained. ese findings could have a guiding importance on the analysis of the propagation of oblique stress waves in the infilled joint as well as on complicated engineering calculations

Testing Program Design and Specimen Preparation
Test Results and Analysis
Stress Attenuation in the Infilled Joint

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