Research on the width of filling body in gob-side entry retaining with high-water materials

To determine the filling body’s width along the gob-side remained roadway which is underneath the gob, the authors analyzed the interaction mechanism between the roof and the supporting body along the remained roadway, based on the elastic thin plate theory of the stope roof. The stress state and mechanical response of the filling body along the remained roadway were studied. Specifically, firstly, the supporting pressure of the coal pillar which is on one side of the gob-side remained roadway was deduced. Also, an equation that is used to calculate the width of the balance area in the stress limit state was acquired. Then, an equation that is used to calculate the roof cutting force on one side of the supporting body was obtained. By using FLAC3D, the authors investigated the displacement field and stress field response laws of rock masses around the roadway with different filling body’s widths. The results show that with the filling body’s width increasing, the supporting ability of the filling body increases. Meanwhile, the rock mass displacement around the roadway and the filling body deformation decrease. The better the filling body’s supporting effect is, the higher the roof cutting force will be. When the filling body’s width is larger than 3.0 m, its internal bearing ability becomes stable and the filling body’s deformation became non-apparent. Finally, analysis shows that the filling body’s width should be 2.5 m. Furthermore, the authors conducted field tests in the supply roadway 1204, using high-water materials and acquired expected outcomes.