Roof Movement Law and Support Supporting Strength Calculation in Shallow Depth Close Distance Room Mining Gob

In order to realize the safe and high efficient production in a shallow depth close distance room mining goaf, theoretical analysis and numerical simulation were used to get the roof movement law and the rational support strength based on geological conditions in Dadijing Coal Mine. The results show that the depth of stress concentration is about 20 m which implies that main roof movement of 3^# coal seam can be affected by the left coal pillars in 2^# coal seam. The main roof tends to instability because of slide and rotary which appears by turns and the vertical stress concentration factor in the support control area is 1.30 under coal pillar. The theoretical analysis show that the rational support strength is 0.82 to 0.93 MPa in the common shallow depth seam and under the room mining goaf the rational support strength will be 1.07 to 1.21 MPa considering the impact of stress concentration.