Study On The Water Transmitting Mechanism While Fault Belt Activated In Fully Mechanized Top-Coal Caving

The fully mechanized top-coal caving is an efficient coal mining technique that has been developed in recent years. But the height and distribution of the fractured zone got enlarged than ever before. The water-inrush accident is happened easily while fault activated. This paper mostly researches on the rule of roof failure near fault belt and the mechanism of water transmitting while fault belt activated in fully mechanized top-coal caving.The author gets the relationship between the maximal height of fractured zone and the thickness of coal seam through numerical simulation and field detection: H = 9 .46M+7.33And the height of fractured zone near fault is about 40% higher than normal.The relationship between permeability and stress-strain of rock is determined through permeability test of complete stress-strain process with stress adding and reducing from three axes. The permeability of rocks is never constant under different stress and stress condition; and the peak value of the rock appears in the stage of strain softening after rock damaging.Hydraulic fracturing field test is analogized through the analogue method of indoor drill hydro-fracturing. And the water resistance coefficient of rock stratum is determined. Parts of water resistance coefficient of derivative rock are determined combining research production of predecessor.When lutaceous mass is in the majority of fault filling and the fault filling appears slimy condition. And the lutaceous mass has good water-Resistant ability and regenerative water-Resistant ability. The water resistance coefficient of fault zone could reach 0.12MPa/m under the original condition.The illustration of water-inrush from roof is analyzed. And the author gets the mechanism of water transmitting while fault belt activated in fully mechanized top-coal caving through by model testing which is independently designed. The process of filling of fault extruded and quantity of water-inrush under different stress is observed. And the mechanism is discussed through mechanics of fractured rock caused by mining and theoretics of seepage.Coal mining gets the falling and fractured of roof, and fractured zone formed, the upper terrane bends and sinks down. All of these bring the displacement of two walls of fault (fault activated), and the water resistance coefficient of fault zone descends. In the process of water-inrush under high stress, seepage conversed from seepage phase to cranny flow phase and pipeline flow phase along with the filling of fault extruded. At last the accident of water-inrush caused by fault occurs.