Reasonable staggered distance determination and overburden damage characteristics for simultaneous mining faces in contiguous coal seams
To determine the reasonable staggered distance of the contiguous coal seams and reveal the evolution of overburden fracture development,the theoretical model was used to calculate the damage depth of the upper coal seam floor and the staggered distance for the 02 and 2 coal seams group.A numerical model was established to analyze the distribution of abutment stress for the middle rock strata under the conditions of 35 meters,40 meters,and 45 meters staggered distances.Physical simulation experiments were also performed to study the characteristics of overburden fracture evolution.The results showed that the abutment stress of the upper coal seam was transmitted to the floor rock through the working face,and the damage depth was 5.45 meters.The maximum influence range of the abutment pressure in the floor rock layers behind working face was close to 38 meters.The abutment pressures of the interlayer rock layers experienced two peaks.When the staggered distance was 40 meters,both peaks of abutment pressures above the lower coal seam working face were smaller,and the reasonable staggered distance was determined to be 40 meters.The initial and periodic collapse intervals of upper working face roof were 40 meters and 15～20 meters,respectively,while those of the main roof of lower working face were significantly increased to 80 meters and 20～30 meters.When the staggered distance for the two mining faces was 40 meters,the lower coal seam working face was less affected by the mining of the upper coal seam.
NETL
NSTL
万方数据
