## 1 Introduction  
An inclined coal seam is distributed in the southwest of China and is mostly high-quality and scarce coal. In order to increase production of high-quality coal resources and improve the tension between mining and excavation, gob-side entry retaining (GER) technology is often used in inclined coal seams [1, 2]. After the GER in an inclined coal seam is affected by multiple minimys, the law of mining pressure is significantly different from that of horizontal coal seam GER under the combined influence of the stress direction and the dip angle of the coal seam. The deformation and failure of the surrounding rock of the roadway are serious [3, 4, 5], exhibiting nonuniform deformation characteristics and significantly increasing the difficulty of roadway maintenance, making the stability of GER increasingly prominent [6, 7, 8]. Therefore, studying the nonuniform expansion mechanism and stability control method for the plastic zone in an inclined coal seam for the diffusion and application of GER technology is critically important. In recent decades, many researchers have studied the deformation and failure characteristics and the stability control of surrounding rock in inclined coal seams. Researchers have found that there are differences in the bearing capacity of different positions in the GER, and the deformation and failure of the surrounding rock show obvious asymmetric characteristics [9; 10; 11]; moreover, the deformation of the surrounding rock is more sensitive to the influence of mining in the secondary mining stage, and the plastic failure zone of the surrounding rock at the edge of the goat is larger [12; 13]. It is further found that the greater the rotation angle of the principal stress direction in the regional stress field, the more obvious the alienation expansion of the plastic zone and the greater the degree of deformation and failure of the roadway, and the height of the hidden roof falls [14]. Therefore, based on the structural mechanics of key blocks in GER, scholars analyzed the influence of support resistance in roadway and roadside support resistance on the stability of key blocks and proposed that high-strength support should be used in roadways to reduce roof rotation and subsidence; further, roadside support should adopt filling materials with high early strength and fast resistance increasing speed [15; 16; 17] so as to adapt to the stage of increasing speed, decreasing speed and stable speed of surrounding rock deformation in GER [18]. The deformation of surrounding rock can be effectively controlled by the asymmetric coupling control technology of narrow flexible formwork wall partition [19]. Previously published studies have focused on the deformation characteristics and failure mechanism of GER, control technology and roadside support resistance. However, the studies on the deformation model of surrounding rock during the overall service period of GER and the common influence of coal seam dip angle and stress field direction on the surrounding rock failure of GER have been sparse. Therefore, the 3131 headentry of a mine in Sichuan is taken as the case study in this paper, focusing on the evolution law of the plastic zone of the surrounding rock and the direction of the principal stress in the stress field of the GER in inclined coal seams, revealing the nonuniform deformation mechanism of the GER in inclined coal seams and proposing control countermeasures. The remaining part of the article proceeds as follows: In Section 3, the deformation law of surrounding rock along the GER is obtained, and the distribution patterns and evolution trend of the plastic zone and stress direction of surrounding rock in the full-service stage of the inclined coal seam along the GER are analyzed in Section 4.