Abstract:
In order to study the effects of multi factor coupling on micro-cracks, stress changes, outburst velocity, and outburst distance during coal and gas outbursts, including geostress, gas pressure, and dynamic disturbances, based on the particle method, we establish a numerical model to simulate the process of coal and gas outburst. Firstly, different vertical and horizontal stress conditions are applied to the model to simulate the characteristics of coal and gas outburst speed, outburst distance, crack propagation when the initial gas pressure is 1.0 MPa. Then, four gas pressure gradients of 0.25, 0.5, 1.0, 2.0 MPa were set under the condition of vertical and horizontal stress of 12 MPa and 9.6 MPa, and the influence of gas pressure on coal and gas outburst process was studied. Finally, dynamic loads are applied to three sets of boundary conditions that did not cause coal and gas outbursts in the previous two simulation environments to explore the impact of dynamic disturbances on coal and gas outbursts. Research has shown that stress mainly provides the driving force for coal and gas outbursts, accelerating the destruction of the coal body. The higher the stress, the faster the coal particles outburst, and the farther the outburst distance. Stress plays a dominant role in the development and occurrence of stress dominated outbursts. Gas pressure can to some extent reduce the difficulty of coal and gas outbursts, but when the gas pressure is too low, it will limit the occurrence of disasters. The main impact of dynamic disturbance on coal and gas outbursts is that it leads to the expansion and development of coal rock fractures, promoting gas desorption. Moreover, when the stress level is low, dynamic disturbances can also become a triggering factor for outburst occurrences.