The outward dislocation sliding of roadway sides with mudstone interlayer in a large height mining face is a new research topic in roadway support. Convergence measurement and borehole observation are conducted on coal seam 5-2 with soft interlayer in Sandaogou Coal mine. It is found that there are vertical cracks in the roadway roof

and side failure zones occur near the mudstone interlayer but failure zones are more obvious in the pillar side. The roadway deformation is mainly caused by adjacent mining goaf. Both numerical simulation and physical simulation are used to reveal the mechanisms of side outward dislocation sliding. The lateral abutment pressure of adjacent mining goaf induces vertical cracks at the roadway roof

which leads to the outward sliding of roof with the upper side along the soft interlayer. Thus

we propose a self-stable equilibrium arching support model of the roadway with a soft interlayer

and develop support principles to strengthen upper sides and control outward sliding failure

and design a support scheme for sides reinforced by long bolts and roof supported by cables. The designed scheme is verified in engineering practices.