Orifices Stress Concentration Study by Static and Dynamic Combination Loads

By the use of the experimental system of Impact Rockburst, which was designed by State Key Laboratory for GeoMechanics and Deep Underground Engineering, the stress concentration for orifices in a cubic gypsum specimen subjected to static and dynamic combination loads was studied. The different triaxial precompression was loaded on gypsum specimen, then the dynamic cyclic loading is exerted in the direction of σ1, while the constant stress is exerted in σ2 and σ3. For the stress strain curve, the data of force and displacement were collected by the servo control system in real time. By the strain gauge near the orifices, the strain was recorded by the dynamic strain collecting device, that result in the orifices stress was obtained. In addition, the phenomenon of inner wall of the orifices was real-time photographed. Based on elastic theory and dynamic stress concentration theory, we calculated the stress near the orifices, which keep pace with the results of test.