Floor heave control mechanism of inner interlocked gas tail road based on reinforced concrete pillar

In order to solve the problem of severe floor heave in inner interlocked tail road of high gassy fully mecha- nized top-coal caving face,the mechanism of floor heave was revealed and one of its targeted control methods was put forward through field measurement,theoretical analysis and analogue simulation. The research results show that under the influence of abutment pressure,shear failure occurs on the two sides of floor which is cut into triangular area. Then linear shaped floor heave is formed because the triangular area is lifted by its undersides plastic zone. Because of the strong influence of mining,the loosen zone is expanded and the effective span of the roadway is also expanded. New shear sliding plane is formed in the floor,and more and more coals participate in the floor heave which leads to the more serious floor heave. Based on the mechanism of floor heave in inner interlocked gas tail road and its special re- quirements for supporting,a new type of reinforced concrete pillar with large base was invented. A row of reinforced concrete pillars are set along the tail road axis which can transfer the roof pressure to the floor so that the floor is ap- plied by the reverse constraint,and the load in ribs is decreased so the loosen zone in ribs is restrained. Thus,floor heave control is finally achieved. The control method of floor heave was used in inner interlocked tail gas road in the Workface 80704 of the second mine of Yangquan Group,and some remarkable effects were achieved.