Abstract: In order to study the roof stability of rectangular roadway in coal mine, we established the mechanics model of rectangular roadway roof based on soil mechanics and elastic mechanics theories. The effect of roadway span length, roof support strength, thickness of side-reinforced rockmass, thickness of roof surrounding rock respectively on the roof stability were analyzed. Results showed that stress in the surrounding rock of rectangular roadway roof were apparently distributed in an arch shape. Contour of shallow stress in the surrounding rock of the roof was an independent egg shape. With the increase of surrounding rock thickness, two independent arches superposed and the stress contour became a general circular arch shape, which wrapped the two independent walls in the arch span. When span length increased to 2≤l/b≤5, arch effect accelerated its attenuation, and the self-bearing capacity of roof surrounding rock reduced rapidly; when l/b>5, uplift force caused by support became the major additional stress in the surrounding rock, and the superimposed stresses of the two walls generally equaled to zero, which suggested that the arch effect gradually disappeared. Furthermore, on the basis of Mohr-Coulomb theory, the governing equation of roof stability was derived.

Key words: rectangular roadway, stress arch, mechanics model, stability