Research On Seismic Wave Field Characteristics Of The Goaf In Coal Mines

Nowadays, as an issue that is closely related to the efficiency of development and utilization of coal resources as well as the security of people's lives and property, the topic about safety in coal production is becoming widely concerned by the public with the increasing demand of coal resources. Since laws and regulations in coal industry was left imperfect, so private digging and abuse of mining were common in the last few decades in China, which resulted in the existence of goaf and old kiln in most large coal mining areas in China, lots of which have been filled with harmful gas and water that made these goaf and old kiln a big hidden danger that threatened the safety to a large extent in coal production.As an effective Geophysical prospecting method in detecting the Geological structures in coal fields, Seismic exploration had already been certified by a lot of successful exploration practices for its effectiveness. The working principle of Seismic exploration is to distinguish the underground reflective interface by detecting the impedance difference of the media above and beneath the interface, which is the essential condition in generating reflected Seismic wave. As to the goaf, there definitely have this impedance difference between media in and out of the goaf, no matter whether there are collapse exist and whether there are water and gas filling in, which provide theoretical possibilities in distinguishing the Seismic respond stimulated by the interface. At the same time, a lot of research and exploration examples have tested the effect of goaf detection by Seismic exploration method, which verified the feasibility of the above mentioned method. According to the basic principle stated above, the research objective of this thesis is to provide theoretical and practical basis to the reliability in distinguishing the goaf by Seismic exploration method, from which the efficiency of the Seismic exploration in detecting the goaf in coal mines would be promoted.Based on the research objectives stated above, the basic foundation of Seismic exploration, goaf detection as well as Seismic forward simulation was firstly illustrated in this thesis, which had laid a basis for the subsequent chapters. In the main contents of this thesis the Seismic full-wave field modeling software Tesseral 2-D was introduced into the forward modeling to the Seismic response of the goaf, then the Seismic data obtained from the simulation was processed and analyzed, after which the Seismic response of the goaf on the simulated time section was analyzed and compared emphatically. Apart from the above stated contents, the practical Seismic response of the goaf obtained from the exploration example was analyzed and then compared with the theoretical Seismic respond concluded in the forward simulation, from the comparison the theoretical and practical Seismic wave field characteristics of the goaf was concluded and then the similarities and differences between the theoretical and the practical Seismic response was illustrated. After which the interpretation of the goaf by using Seismic data was discussed and the conclusion of this thesis was finally drawn, which had indicated the type and size of the goaf that can be detected by Seismic exploration method. The research work of this thesis would provide theoretical significance as well as the practical instruments to the follow up research on the detection and management of the goaf in coal mines as well as the subsequent prevention of the possible disasters resulted from the goaf.