Hard particle force in a soft fracture.

The fissure patency of a rock mass is an important factor contributing towards the fluid production efficiency. Debris particles generated by the crushing of rock masses or other external forces can cause blockage or promote the smoothness of rock fractures. It is of immense theoretical and engineering value to analyze the mechanics of particles in rock fissures, especially under the compression of rock from both sides. In this study, through static analysis, the resultant force of particles in rock fissures is extruded by rock on both sides. The following conclusions are drawn: The resultant force increases first and then decrease with the increase of fissure angle and width when x is constant. The extreme point is at sinθ = R/(3x), h = 2 R(9x - R)/(9x) and the maximum of F is 8πkR/(27x). Whereas, the bigger the joint roughness coefficient (JRC) of fissure is, the larger the average of fissure open angle is and the larger the average width is. As the JRC increases, the average resultant force decreases. The sharp point at the turning point of the fissure is easily broken, and the fissure width becomes larger, which makes the resultant force decrease. The analysis process expands the application prospects of the JRC. The results help to better understand the blockage and transport of particles in rock fissures.