Study on water inrush warning information of coal seam floor fault structure

Abstract

Water inrush from coal floor is a gradual process from generation, and development to disaster. In this process, the geophysical information received by the rock mass will show measurable characteristics of the sudden, and the occurrence of water inrush is the inevitable reflection of various characteristics of the sudden in the limit state. In order to study the early warning information before water inrush in working face, based on the fluid-solid coupling theory, similar simulation test and FLAC3D simulation were used to reproduce the water inrush process of the floor fracture structure, to clarify the difference of response characteristics of each physical quantity before and after water inrush, and to calculate the weight value of different physical quantities in the water inrush process combined with entropy method. The results show that when the working face is gradually approaching the penetrating fault, the stress at the water inrush position of the floor rock layer decreases sharply, and the step jump change occurs after reaching the minimum peak value. The water flow shows a stable increase–sudden increase process. Water inrush through fault location water flow presents increasing—stability—the changing process of surge, water pressure appears cliff-like drop. In the sub-emergent stage when water inrush is about to occur in the working face, the variation range of stress and water pressure at the position of water inrush is more intense. The increase rate of stress at the position of water inrush in the floor rock layer increases sharply and reaches the peak value in a short time, while the increase rate of water pressure at the position of water inrush through the fault decreases.