Abstract: When there is a layer or several layers of hard rock seam roof, the stress concentration in lateral rock increases with increase of mining height, which leads to the widening of the roadway coal pillars. In order to reduce the width of the roadway coal pillars, a technological principle of cutting different depth fracture along roadway in roof is proposed. A systematic study of the surrounding rock stress transfer and control is conducted through similar simulation and numerical simulation when roadside roof has been cut at different depth. The impact of cutting fracture depth on strata breakage and roof sinking is revealed. The results show that: with the increase of kerf depth, the rock stress of goaf decreases gradually; the higher the rock strata is, the smaller the stress is. With the increase of cutting fracture height of the lateral goaf roof, the rock stress above the coal pillars increases gradually; the higher the rock strata is, the bigger the stress becomes. The rock stress above the coal pillars(10 m and 20 m) and the distance from peak stress to cutting fracture edge are in nonlinear inverse relationship with cutting depth. While the strata stress at 10 m and 20 m above the goaf shows an exponential relationship with cutting depth. It means that the deep cutting can effectively control the distribution of strata stress, stress maximum and the distance of peak point from the edge of cutting fracture.

Key words: roof, stress transmission, cutting depth, rock stress distribution