The question of how to mine safely in close multi coal seams is the main concern for coal operators, in particular for large-dip coal seams with complex geological and mechanical conditions. This paper presents a detailed similarity simulation on the movement characteristics of the overburden and the stress distribution of underlying strata in terms of a specific coal mine in the Tielieke mining area of the Kubai coalfield via a three-dimensional photogrammetry system and a high-speed static resistance analyzer. The results show that the overburden strata are asymmetrically deformed around the coal pillar and the fracture area is perpendicular to the longwall with an “M” shape when deeper coal is mined. Moreover, the asymmetric movement of overburden results in the non-uniform distribution of stress on the floor of the coal pillar and ribs. In particular, stress is closely related to the location of the longwall, and stress of the coal pillar is much larger when it is closer to the deep side. The floor stress relief degree of the longwall in the deep zone is higher than that of its counterparts, providing a theoretical foundation for a reasonable layout and a support technique for roadways. The main contribution of this research that it can be used as a reference in maintaining the integrity of surrounding rock for large-dip coal seams with close distances.

This study, conducted in the geological context of the Yixin coalfield, systematically performed indoor mechanical tests to analyze the impact of different stress conditions on the permeability of weakly cemented sandstone. The results were used to establish numerical simulations of permeability curves, revealing the following key findings. (1) After saturation, weakly cemented sandstone transitions from brittle to plastic failure. Numerical simulations closely matched experimental results, ensuring the accuracy of subsequent permeability simulations using the Hoek–Brown method. (2) Indoor permeability experiments identified a unique “√” shaped permeability curve for weakly cemented sandstone, differing from traditional sandstone. Numerical simulations confirmed this pattern and provided a basis for modeling weakly cemented strata under varying confining pressures. (3) The mesoscopic analysis of numerical simulation shows that that confining pressure limits the expansion of microcracks, while pore pressure causes cracks to develop from high- to low-pressure areas. Increasing pore pressure gradually raises permeability, and elevated confining pressure initially reduces, then increases permeability. (4) A damage parameter “D” was introduced to monitor fractures during compression simulations, showing that with increasing confining pressure, the damage parameter decreases and then sharply increases. Hydraulic pressure differentials directly correlated with the damage. This comprehensive study enhances our understanding of weakly cemented sandstone’s hydrological behavior under varying stress conditions and parameters.

In the process of roadway excavation in thick and hard coal seams with a hard roof, the instantaneous release of a large amount of elastic energy accumulated in coal and rock mass causes disasters. Especially under the action of tectonic stress, dynamic disasters of roadway-surrounding rock are extremely strong. Therefore, this paper takes the 110,505 roadway of the Yushuling Coal Mine as the engineering background. Aiming at the serious deformation of roadway-surrounding rock and the problem of strong mine pressure, the deformation mechanism of roadway-surrounding rock is studied by means of theoretical analysis, indoor experimentation, numerical simulation and field testing, and the surrounding rock control technology is proposed. Firstly, the results show that the stress field type of the Yushuling Coal Mine is a ${\sigma }_{Hv}$ type, the azimuth angle of the maximum horizontal principal stress is concentrated in 110.30°~114.12°, the dip angle is −33.04°~−3.43°, and the maximum horizontal principal stress is 1.94~2.76 times of the minimum horizontal principal stress. Secondly, the brittleness index of No. 5 is 0.62; the failure energy release of the surrounding rock compressive energy floor rock sample is up to 150,000 mv * ms. The more the cumulative number of rock samples, the greater the strength, and the more severe the damage. Thirdly, with the increase in tectonic stress, the stress of roadway-surrounding rock is asymmetrically distributed, and the plastic zone develops along the tendency. The maximum range of the plastic zone expands from 4.18 m to 10.19 m. Lastly, according to the deformation characteristics of roadway-surrounding rock, left side > roof > right side > floor, the surrounding rock control technology of ‘asymmetric anchor net cable support + borehole pressure relief’ is proposed, which realizes the effective control of roadway-surrounding rock deformation.