Mechanism And Prevention Techniques Of the hazardous Burst of Interlayer-sagging Water Body
Bai, Haibo; Wu, Luyuan; Wu, Guangming; He, Shixin
China University of Mining & Technology, China, People's Republic of
When the coal roof is controlled by the full caving method, the normal tensile may cause the overlying rock layers composed of hard and soft formations to yield uncoordinated sagging deformations or even a large interlay lenticular-like void space. Then, when the interlayer-sagging-void-space expands and water accumulates to a certain amount, the rock burst of the upper hard rock and the hydrostatic water pressure could cause the interlayer-sagging water to burst into the stope, which would cause a disaster like what the goaf water inrush does. In order to investigate the disaster mechanism and to control this kind of disasters, field investigation, simulation tests, theoretical analysis were carried out.
The results showed that: (1) Conditions to accumulate interlayer-sagging water include upper hard rock layers with a certain thickness, water-proof layers between the lower position and the stope, and enough interlayer-sagging void space; (2) interlayer-sagging water burst is caused by the forces of hydrostatic water head of the sagging water and the rock burst force of the hard rock layer; (3) sagging water may burst through the channels directly forced by the rock burst and hydrostatic pressure, Water-conducting cracks, geologic faults activated by mining and neotectonic faults.
A comprehensive preventions measures involve in: (1) pre-dewater the interlayer-sagging water body via underground drilling; (2) Pre-dewater the aquifers which may potentially recharge the sagging water body;(3) Increasing the size of working face to limit the development of sagging strata; (4) strengthen the capacity to buffer and eliminate water inrush in a short time. Practice proves that the method is correct and the effect is great.