Study On Seismic Wave Characteristics Of Small And Medium Scale Faults Ahead Of Mine Roadway And Application

Coal mining conditions are complex in China, and safety accidents of mine happen frequently, among which the most serious is the mine gas accident in coal mining. The main reason for the frequent occurrence of coal and gas outburst is the exploration of the geological structure in front of the coal drift driving working face. At present, the prediction of gas geological abnormality by using geophysical method has become a research focus in mine roadway. Therefore, it has important theoretical and practical significance to study of the advance detection and diagnosis of typical gas geological anomalies(small faults) based on seismic wave method.In this paper, the following models are established: the model of advanced detection system for different source and receiving points, numerical model of isotropic medium with different small faults(normal/inverse, position and drop) in the face of the medium thick and thick coal seam and model of the difference between roadway height and coal seam height in heading face. Consider effect of seam cavity, the spatial high-order staggered grid algorithm was used to do the numerical simulation, seismic wave field characteristics of small faults was comparative analysed that condition of different source and receiving point position, the condition of coal thickness and different fault properties(forward/reverse, location and drop). The research results show that: 1)source in head-on position excitation is be larger acoustic interference and focal in head-on coal seam ahead when excited, small fault of diffraction shaped clear, strong energy and diffraction row short. 2)When the receiver is shallow depths, acoustic and top of roof-floor reflected wave interference is serious, and small fault effective wave signal to noise ratio is low; when receiving hole deepth is 4m, diffraction energy is strong, and in-phase axis is clear, which level of X component effective wave signal is better. 3)Diffraction can be obviously distinguished when the fault gap is relatively large fault footwall breakpoint. 4)Under conditions of normal and reverse fault, the different positions of the source will affect the reception of the effective wave signals of normal/inverse fault, which the effective signals of reverse fault is better. 5)Compared with the advanced detection of the medium and thick coal seams, the effective wave signal of the small fault is better than that of the thick coal seam under the condition of thick seam. 6)In medium thick coal seam along the roof-floor driving conditions, small faults with a breakpoint in two groups of high energy diffraction, which are rock body wave and the trough of the wave propagation to the breakpoint of small faults.There are carry out the field detection contrast test in coal and gas outburst mine roadway of the typical mining area of Shanxi. The results show that seismic wave method by advanced detection technology can provide technical support through the location of abnormal amplitude energy alteration diagnosis of gas geology, which is safe and efficient coal mine tunneling.