Background: To optimize the layout position of the residual coal pillar return roadway when mining a close coal seam group and to clarify the optimization mechanism, a roadway optimization layout analysis was conducted on the Tashan coal mine. Methods: Surface displacement monitoring was conducted using field tests, and the main stress magnitude, plastic zone morphology, deformation variables, and connectivity between the plastic zone of the roadway and the plastic zone of the residual coal pillar were analyzed at different locations with the help of FLAC3D numerical simulation software. Results: It was found that, in the process of close coal seam group mining, the residual coal pillar of the overlying coal seam seriously affects the stress state and plastic zone distribution of the lower coal seam roadway. The roadway is arranged in a position that is relatively far away from the residual coal pillar, which could reduce the stress influence of the residual coal pillar on the roadway and guarantee the stability of the roadway. Conclusion: Since the Tashan Mine uses the top release method for mining, the stability of the roadway can be better ensured by placing the roadway in the middle and lower regions of the coal seam and using the layout method to retain small coal pillars.

In order to study the effect of interlayer thickness on the deformation and strength characteristics of interbedded sandstone under load, uniaxial compression and conventional triaxial compression tests were carried out on four interbedded medium-grained sandstone samples with different interlayer thickness, accounting for different proportions of the total height of the sample (5%, 10%, 15%, and 20%). The samples were from the Shendong Mining Area and investigated using an RMT-150C rock mechanics test system. Then the stress–strain curve characteristics, strength characteristics, and failure characteristics of the interbedded medium-grained sandstone with different interlayer thickness were analyzed, and the applicability of Mohr–Coulomb strength criterion and Rocker criterion to interbedded medium-grained sandstone with different interlayer thickness was evaluated. The research results show that, as the thickness of the interlayer gradually increases, the uniaxial compressive strength of the sandstone containing the interlayer first decreases and then increases; as the thickness of the interlayer increases, the elastic modulus of the sandstone containing the interlayer gradually decreases, and the peak strain increases gradually; the thickness of the interlayer has little effect on the triaxial compressive strength of the sandstone containing the interlayer. When the thickness of the interlayer is small, the deviation of the fitted uniaxial compressive strength of the Rocker strength criterion is relatively small, and the applicability is good; the prediction result of the uniaxial compressive strength of the Mohr–Coulomb strength criterion is better; for the tensile strength of the interlayer rock, the Rocker strength criterion has good applicability. The existence of the interlayer hinders the development of medium-grained sandstone cracks, but this effect is weakened with the increasing thickness of the interlayer. The research results are helpful to further reveal the movement law of overlying rocks in Shendong mining area, and provide basic parameters for related research.

Based on the special spatial position of 1–2 coal and 2–2 coal, this paper adopts a new way of modeling by fish and overcomes the difficulty of modeling, simulates the influence of the coal pillar on the 22,206 return airway after mining 1–2 coal seam by Flac3D, studies the 22,206 return airway under the influence of primary and secondary mining, and puts forward the support scheme of the 22,206 return airway. The following conclusions are obtained: (1) After mining 1–2 coal, the stress of the 22,206–return airway under the residual coal pillar of 1–2 coal increased. The maximum stress position is below the middle coal pillar of 1–2 coal, and its maximum vertical stress (σv_max) and maximum horizontal stress (σh_max) are 6.24 MPa and 4.09 MPa, respectively. (2) The rule of 22,206 return airway’s pressure appearance is that the stress and plastic zone becomes larger when near the coal pillar, becomes smaller when far from the coal pillar, the maximum failure radius of roof and floor is only 1.3 m, and 0.6 m, the maximum failure radius of roadway side is 0.6 m and 1.5 m after the second mining. (3) According to the proposed support scheme, field experiments found that the maximum displacement is less than 120 mm, which can effectively guarantee the stability of the roadway.