An SHPB test study on wave propagation across rock masses with different contact area ratios of joint

• Published in: International journal of impact engineering Vol. 105; pp. 109 - 116
• Main Authors: Li, J.C., Li, N.N., Li, H.B., Zhao, J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2017; Elsevier BV
• Subjects: Contact; Contact pressure; Cylinders; Deformation; Dynamic behavior of rock joint; Geometry; Joint matching coefficient; Jointed rock mass; Measuring instruments; Notches; Propaganda; Reflected waves; Rocks; SHPB test; Split Hopkinson pressure bars; Strain gauges; Stress propagation; Ultrasonic testing; Wave propagation; Wave reflection; Joint matching coefficient; Dynamic behavior of rock joint; Wave propagation; SHPB test; Jointed rock mass
• ISSN: 0734-743X; 1879-3509
• DOI: 10.1016/j.ijimpeng.2016.12.011

•An SHPB test was conducted to study wave propagation across rock masses.•The effect of joint contact area ratio on wave propagation was analyzed.•The effect of spatial geometry of joint surface on wave propagation was studied.•The effect of joint matching coefficient on joint stress-closure relation is revealed. The Split Hopkinson Pressure Bar (SHPB) apparatus was adopted to investigate the influence of joint contact area and spatial geometry of joint surface on the dynamic property of rock joint and wave propagation. The specimen was comprised of two rock cylinders. The top surfaces of the two cylinders contacted with each other, and their bottom surfaces contacted with the input and output bars of the SHPB apparatus, respectively. One top surface of one cylinder was sawn to shape a number of notches, while the other surfaces of the two cylinders were smooth and flat. The artificial rock joint was modeled as the contacted top surfaces of the two cylinders. The area ratio of contact between joint surfaces equals to the joint matching coefficient (JMC). The incident, transmitted and reflected waves were recorded from the strain gauges mounted on the input and output bars. Then, the transmission and reflection coefficients for strain wave propagation across the rock specimen were obtained. Based on the basic theory of SHPB tests, the stress on the specimen, the deformation of rock specimen and the stress-closure relation of joint were analyzed. The experimental results show that the JMC and the spatial geometry of joint surface affect not only the dynamic behavior of joint but also the stress wave propagation.