Experimental Research on the Properties of “Solid–Gas” Coupling Physical Simulation Similar Materials and Testing by Computer of Gas in Coal Rock

On the basis of research into solid similar materials, a similarity criterion applying to “solid–gas” coupling of gas in coal rock is presented according to the “solid–fluid” coupling similarity theory. With sand as the aggregate and paraffin and oil as the cementing agents, a kind of materials suitable for “solid–gas” coupling simulation experiment is developed. Through lots of experiments, physical mechanics of similar materials are tested, such as compressive strength, brittle parameter, and permeation rate. By resorting to the self-developed device, tests are also made on the seepage of specimens of similar materials containing cementing agents of different contents. The findings indicate that with the continuous rise of paraffin content, the compressive strength of materials is increasing accordingly, and the seepage is decreasing gradually; and the change of oil content helps eliminate the shortcoming that compressive strength is changing significantly when only paraffin is used. Rocks of different strengths and different seepages can be simulated through the reasonable adjustment of the proportions of paraffin and oil by computer. Under the precondition that mechanical parameters meet requirements of simulated rocks, the paper conducts a comparison between and experimental analysis of the seepage velocities of the developed new material and the original solid similar material, and draws the conclusion that the developed material can remarkably reduce the seepage velocity of gas in it. Meanwhile, the material is also applied to the model experiment of coal mining, and effectively reveals the relationship between gas seepage rate and overlying rock movement.