Experimental study on rock strata movement and stope stress distribution law under mining height regulation

Abstract

When pressure relief mining of a non‐all‐coal protective layer, to realize the accurate regulation of the pressure relief range and pressure release value of mining height, it is necessary to carry out research on the migration of overburden and the stress distribution law of stope under mining height control. Through similar material simulation experiments, four groups of similar material simulation experimental models were established. The laws of rock strata movement and stress distribution at 2, 4, and 5 m mining heights under different geological conditions, and the laws of rock strata movement and stress distribution at 5 and 8 m mining heights under the same geological conditions were obtained. The research results show that the geological conditions and mining height do not affect the evolution of the rock strata movement range. The highest position of the strata movement and deformation is linearly related to the advancing distance of the coalface. The maximum height of rock strata movement increases abruptly when encountering the key strata, but it still has a linear relationship. The highest position of each expansion of the fracture zone has an exponential relationship with the advancing distance of the coalface. When the key strata are encountered, the maximum height of the fracture zone increases abruptly. The change in mining height only affects the distribution range of the “three zones.” The mining height controls the stress distribution of stope by adjusting the “three zones” of the roof. With the increase in mining height, the caving zone and fracture zone range increase. The corresponding pressure relief range and pressure relief value show the change law of first increasing and then decreasing. There is an optimal mining height, which can make the pressure relief effect of stope best.