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

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.

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