Study on width design of small coal pillar and support technology of gob-sideentry driving by fully-mechanized top coal caving

In order to determine reasonable width of small coal pillar and support method of gob-side entry driving,taking No.8407 working face of Yangquan No.5 Mine as the example,based on main roof fracture model and the ultimate balanced theory,calculated the upper and lower limit values of coal pillar,the stress distribution of coal pillar was studied during the mining period by adopting the method of borehole stress measurement.The support parameters of gob-side entry driving was also calculated.Results showed that the width of small coal pillar should be chosen between 9.03 m and 10.81 m,the optimal width of coal pillar was 10 m,the coal pillar range from 0 to 3 m was damaged,range from 3 to 6 m was elastic core area,range from 6 to 10 m close to No.8409 goaf and the carrying capacity was weak.Thus,the anchor and long and short anchor cable were used to support the roadway during the time of excavation,and then the coal pillar was reinforced by grouting of 3 m drilling during period of mining.Monitoring results confirmed that deformation of roadway changed slightly during the time of excavation,the maximum deformation of roof and grouted small coal pillar side and coal side were 0.20 m,0.05 m and 1.00 m,the deformation of surrounding rock was controllable,realized safety and efficient mining in fully-mechanized top coal caving.