A study of crack initiation and source mechanism in the Brazilian test based on moment tensor

Griffith-based analysis of crack initiation location in a Brazilian test

“…The protocol is exemplified with two examples of valid and invalid tests, taken from the literature. Specifically, we take as case studies the experiments by Sun and Wu [32] on sandstone using the ISRM test configuration and the work by Duevel and Haimson [33] on granite, also using the ISRM recommended testing geometry. In both cases the jaws were made of steel, with elastic properties E j = 210 GPa and ν j = 0.3.…”

“…For the sandstone tested in Ref. [32], the reported elastic properties are E d = 19.15 GPa and ν d = 0.17 and the material compressive strength is σ c = 99.93 MPa. For the pink Lac du Bonnet granite study by Duevel and Haimson, the elastic properties are given by E d = 74.2 GPa and ν d = 0.25, while the compressive strength was found to be σ c = 219 MPa [33,34].…”

“…The Brazilian tests conducted in Ref. [32] and Ref. [33] led to tensile strengths of σ t = 7.51 MPa and σ t = 11.4 MPa, respectively.…”

“…15 reveal that, while in both case studies the stress state in the disk centre is not described by the point load equation, this approximation provides a good estimate. In the case of the sandstone study by Sun and Wu [32] the error relative to Eq. ( 2) is below 0.5% while in the granite experiment by Duevel and Haimson [33] the error is roughly 0.2%.…”

Study on Gas Control Methods Optimization for Mining Safety

“…9. As the protective seam being mined, three roof zones in vertical direction will be formed, namely, caved zone, fractured zone, and subsidence zone [20,21]. Stress in the protected seams will decrease, fractures generate, and permeability increases, and finally gas desorbs and pressure drops.…”