Study on calculation law of overburden fractures in shallow coal seam mining under peak cluster landform

It is of great significance to study the evolution law of overburden fractures for safe and green mining of shallow coal seams under peak cluster landform in Guizhou.According to the evolution characteristics of overburden fractures in the mining process of shallow coal seam under peak cluster landform in Guizhou Mining Area,combined with the actual engineering geological conditions of Pusa Coal Mine,the spatio-temporal evolution law of overburden fractures in the advancing process of 11013 working face is revealed by numerical simulation and similar simulation experiments.The results show that the numerical simulation results are basically consistent with the similar simulation experiments.When the working face advances to 30 m,the strata above the goaf appear obvious separation cracks.With the continuous advancement of the working face,the basic top appears different degrees of separation cracks and cross-layer cracks.When the working face advances 100-160 m (the surface belongs to the downhill stage),the development speed of overburden fractures increases.When the working face advances about 155 m,cracks appear on the surface of the slope and extend downward,and finally lead to the cracks in the working face.At this time,the maximum development height of overburden fractures is about 108 m,and then it will not continue to develop upward.The development of overburden fractures presents the evolution characteristics of inoculation-expansion-closure,and the overall distribution of overburden fractures is similar to the inclined trapezoidal shape under the action of coal seam dip angle.The research results can provide reference for green mining of working face under similar geological conditions.