Abstract:  In this paper, through the theoretical analysis of instability characteristics of soft rock gateway in high pitched seam, the structured instability equation of the gateway is established, and the coupling support scheme is proposed according to the coupling support idea. Additionally, the comprehensive analysis of the coupling support scheme is further carried out by numerical calculation, similar simulation experiment and practical supporting test. The results show that the instability of gateway roof has an arc asymmetry breaking, while the instability of two sides mainly shows shear slip of the triangle breaking bodies. The serious breaking lies in the upper of side angle, and the breaking in the middle-upper of roof is the inducing point of surrounding instability. Thus, the stability of surrounding rock is related to coal seam angle, shear surface length, and physic-mechanical parameters of coal-rock mass. After gateway supporting, the plastic breaking zone of surrounding rock along the inclination of coal seam is less, and the amount of roof separation is kept in reasonable range. Moreover, the improvement of two-side supporting strength is beneficial to the stability of gateway surrounding rock.

Key words: high-pitched seam, gateway, instability equation, numerical calculation, similar simulation, field monitoring