Development and experimental validation of a test system for simulation of fault-slip rockbursts in coal mine roadways

Abstract

Fault-slip rockbursts are a major type of rockbursts in coal mine roadways, posing great hazards. Currently, there is a lack of systematic research on the entire process of fault-slip rockbursts, and prediction and prevention remain fundamental challenges. To achieve experimental simulation of fault-slip rockbursts, a testing system was developed, along with the development of low-strength high-brittleness similar simulation materials. A large-scale similar model containing faults and roadways was prepared, and a series of verification experiments were conducted, realizing the simulation of roadway shock failure and fault shear slip. The testing system is equipped with a triaxial six-face loading function, with a vertical loading capacity of 20 MPa and a model size of 1.50 m×0.75 m×0.75 m. The main frame innovatively adopts a key plate connection, ensuring high rigidity of the main frame. A honeycomb loading shell structure was invented, achieving oil cylinder group loading, which can meet the requirements of fault-slip rockburst simulation. A similar material suitable for fault-slip rockburst simulation was developed, which uses water glass as the binder, sodium fluosilicate as the curing agent, and talcum powder as the aggregate. The similar material has characteristics of both low strength and high brittleness, with a uniaxial compressive strength ranging from 3.44 to 7.81 MPa, an impact energy index of 9.2, and an elastic energy index of 8.83. Based on the test system and low-strength and high-brittleness materials, the bursting failure simulation of roadway under static load was realized, and the feasibility of simulating bursting failure of roadway using low-strength and high-brittleness materials was verified. The loading conditions of the critical equilibrium state of the roadway were obtained, with the continuous shedding of the roadway's side as a significant precursor characteristic of roadway damage. The shear slip of rough serrated faults was realized, confirming that the shear slip of rough faults would cause significant dynamic load disturbances to the roadway, obtaining a reasonable loading method for fault slip. The method of loading the top of the dynamic zone first and unloading the bottom later can achieve instantaneous slip of the fault and eliminate the influence on the static zone stress state.

Keywords

• fault-slip rockbursts
• test system
• low-strength high-brittleness material
• physical simulation
• roadway bursting failure