Abstract: The broken location of the lower roof determines the broken location of the upper roof and the stability of the surrounding rock in gob-side entry retaining. Generally, the broken location of the lower roof appears near the coal side or outside of entry-side support, which is controlled by the strength of entry-side and entry-in support. In the paper, mechanical models of the lower roof with different broken locations were established based on the limited analysis theory and the mechanical equilibrium theory. The relationships between the entry-side supporting resistance and the broken location of the lower roof were obtained, and the disturbance effects after the broken of the lower roof were analyzed. The results show that it benefits to the maintaining of the entry-side support and coal side if the lower roof breaks outside the entry-side support. And then, the implementation of the bolting support to the roof was analyzed from increasing the resisting bending capacity and tensile strength of the roof and improving the stress environment, which can make the lower roof break tending to the gob.

Key words: gob-side entry retaining, roof, breaking law, entry-side support, entry-in support