Physical model experiment on formation of surface tension fractures and their controlling factors in a coal mining area

Based on the indoor simulation test of self-made device and field test, the influence of clay water content and stress environment change on the development of surface tension fracture in coal mining area is studied. The results show that the width and depth of surface tension fracture of soil sample decrease obviously with the increase of clay water content while the water content is 30%, 35% and 40%;when the water content increases to 40%, there will be no tension cracks on the surface of the soil sample;the artificially formed stress weak area on the surface of the soil sample can effectively change the development position of the tension fracture;in the 1047 working face of Suntuan coal mine, the development of surface “cut fissure” is effectively restrained;the stress guidance has a certain impact on the development direction of surface “fan crack”.