In order to explore the mining pressure development rule of gob‐side entry retaining during deep thin coal seam mining, FLAC^3D numerical simulation is applied to analyze the stress distribution rule of gob‐side entry retaining, observing the left third working face of 49^# coal seam in No. 8 mining area of Xinxing Coal Mine as the research object. The results show that the working face stress field is asymmetrical which is caused by the reserved roadway and the over goaf. After roadway tunneling, features of obvious stress redistribution are formed. The vertical and horizontal stress in the coal seam develop a U‐shaped distribution. The vertical stress in the roadway is less than that in the lower roadway, and the horizontal stress is half that in the lower roadway. The phenomenon of high stress “nucleation” appears and becomes more obvious in the process of working face advancing, and the nuclear body disappears after working face advanced to the boundary line. With the working surface advancing, the trend of horizontal stress of gob‐side entry retaining decreases gradually and the vertical stress of gob‐side entry retaining is less than the original rock stress. The research findings provide a basis for the supporting design of gob‐side entry retaining in the deep thin coal seam and the stability control of surrounding rock.

In order to explore the stability control of surrounding rock in the process of deep mining, comparative analysis of stress, deformation, and fracture characteristics of surrounding rock of deep and shallow mining roadway in dongbaotou coal mine, laboratory experiments, field measurement, numerical simulation, and field industrial experiments were adopted to put forward the control plan of the surrounding rock in deep roadway, which were verified by field industrial experiments. The results of laboratory experiments and field experiments show that the mechanical properties of deep roadway surrounding rock of Dongbaowei Coal Mine are significantly lower than those of the shadow roadway, mainly due to the development of joints and fractures of the overlying strata in the deep stope, serious impact on the disturbance of the roadway which has been made by the strong pressure of the stope, and reduced crushing strength of surrounding rock. Through comparative analysis of deep roadway support plan carried out by numerical simulation, the support scheme suitable for Dongbaowei Coal Mine is put forward, which is applied in the field. Field industrial experiments show that after the optimization of support parameters, the deformation of surrounding rock of roadway is well controlled. The displacement of surrounding rock of roadway is basically stable after 10∼15 days. The support of surrounding rock of roadway has good effect, which achieves the goal of stability control of deep roadway surrounding rock.

With the increase of underground mining depth in coal mines, the distribution of stress fields in deep mining becomes more complex, and the stress localization characteristics are obvious. In order to obtain the local mechanical properties and energy evolution of sandstone, this article is based on the three‐point bending experiment and combined with the localized failure theory to explore the evolution law of stress field, deformation field, and energy field of sandstone specimen under tensile stress during the three‐point bending experiment. The results show that during the three‐point bending test of sandstone, with the increase of the span of the three‐point bending test, the peak stress at the characteristic point shows an increasing trend, and the peak stress has obvious regional characteristics. In the vertical direction, the peak stress at the characteristic points in the upper part of the neutral layer is larger, and the peak stress at the characteristic points in the lower part of the neutral layer is smaller. In the horizontal direction, the peak stress at the characteristic points in the near field is higher, and the peak stress at the characteristic points in the middle field and the far field is smaller. The stress field and the deformation field have a good corresponding relationship. The upper far‐field peak strain tends to decrease with the increase of the span, and the upper near‐field peak strain first decreases and then increases with the increase of the span. The lower near‐field peak strain tends to decrease and then increase with increasing span, and the lower far‐field peak strain fluctuates with increasing span. The energy field is dependent on the stress field and the deformation field, showing obvious regional characteristics. The energy storage and release capacity of the upper area are higher than those of the lower area. The overall performance of the loading energy storage, rebound energy release, and crack propagation energy release in different areas can be described as far field < mid‐field << near field. The near‐field energy at different spans presents the characteristics of two stages. When the span is between 140 mm and 150 mm, the near‐field energy shows a rapid decreasing trend, and when the span is between 150 mm and 180 mm, the near‐field energy presents an obvious increasing trend.

To address the engineering challenges of frequent flexural deformation and instability of composite roadway roofs and the difficulty in accurately controlling the support strength range during deep coal mining, this study takes the soft–hard interbedded composite roof of the working face in the West No. 1 Mining Area of Shuangyang Coal Mine in Shuangyashan as the engineering background. Typical fine sandstone (hard rock) and tuff (soft rock) from the on-site roof were selected to prepare layered composite specimens, and indoor four-point bending tests were conducted. Combined with theoretical calculations, strain monitoring, and acoustic emission (AE) real-time localization technology, the regulatory mechanisms of three key factors—lithological combination, loading rate, and span—on the flexural mechanical properties, deformation and failure modes, and fracture evolution laws of layered composite rock masses were systematically investigated. The research results show the following: (1) The flexural performance of layered composite rock masses is dominated by the interlayer interface effect. Their flexural strength is 46.7% and 41.1% lower than that of single hard rock and soft rock specimens, respectively, and the competitive mechanism between interface slip and delamination fracture is the core inducement of strength deterioration. (2) The strength and deformation characteristics of layered composite rock masses exhibit a significant loading rate effect. When the loading rate increases from 0.002 mm/s to 0.02 mm/s, the flexural strength decreases by 51.8% and the mid-span deformation deflection reduces by 50.1%. High loading rates will exacerbate the deformation mismatch between soft and hard rock layers, trigger premature failure of interface bonding, and inhibit the full development of structural plastic deformation. (3) Increasing the span significantly optimizes the flexural bearing performance of layered composite rock masses. When the span increases from 170 mm to 190 mm, the flexural strength increases by 65.7% and the mid-span deformation deflection synchronously increases by 65.7%. A large span can extend the flexural deformation path, promote the coordinated deformation of rock layers, and suppress local stress concentration. (4) The flexural failure of layered composite rock masses is dominated by Mode II shear cracks, while single-lithology specimens are mainly dominated by Mode I tensile cracks. Loading rate and span significantly change the crack propagation mode and energy release law. This study establishes a calculation method for the equivalent flexural stiffness of layered composite rock masses and reveals the mesoscopic mechanism of flexural failure of heterogeneous layered rock masses. The research results can provide a theoretical basis and experimental support for the optimization of support schemes and the prevention and control of roof collapse hazards for composite roofs of deep coal mine roadways.