Abstract: High stress and low strength of surrounding rock is one of the main causes leading to large plastic deformation of soft rock roadway.The deformation instability mechanism is summarized by analyzing the deformation failure characteristics of the belt transportation lane in a mine and the mechanical state of surrounding rocks.Based on the coupling support theory,two optimized support schemes are proposed,that are the full-section high strength bolt + long anchor cable + control bottom concrete layer coupling support (scheme 1) and the multistage anchor cable + high strength bolt + flexible release pressure pack + U-shaped steel joint support(scheme 2).Then,the support effect of two optimized schemes is simulated by FLAC3D,and the scheme 2 is determined as the optimal support scheme.The industrial test shows that the maximum subsidence,floor heave and two-side moving amount of roadway roof are respectively 37.8mm,97.8mm and 105.3mm after adopting the scheme 2.It can basically control the harmful deformation of surrounding rock.

Key words: High stress, Rheological soft rock, Numerical simulation, Instability mechanism