Study Of Tectonic Stress Field And Its Influence On Gas Outburst

Gas outburst accidents have become one of the most serious natural disasters in mining areas. With the deeper mining, the probability of gas outburst increases gradually, scientific and accurate prediction of gas outburst is urgently required. Tectonic stress field is the controlling factor of gas outburst essentially, the geological structure (such as active fractures) as the macroscopic performance of tectonic stress field anomaly, its precise division is crucial, Geo-dynamic division provides a new method for the geological structure research. Based on the theory of trend surface analysis and mapping technology of secondary development to calling CAD, the paper constructs the visual software system of geological trend surface analysis. Integrating with maps of the geological topography and epicenter distribution; results of the underground investigation and stress measurement in mining areas, the system can effectively divide active fractures, which provides the tectonic framework distribution for numerical simulation of tectonic stress field.Two kinds of methods, hydraulic fracturing method and stress relieving method, are used to measure the original rock stress of four drilling holes on two levels in Daxing mine's in-situ stress measurement, resulting in magnitude and direction of the maximum principal stress, minimum principal stress, gravity stress and the original lithologic parameters of the mine's stress field. The finite element method is used to numerically simulate the tectonic stress field in the level of six hundred meters below geoid in this paper, with obtainment of present distribution regulation of the maximum principal stress, maximum shear stress, minimum principal stress of the mine, which prepares the basic data for gas outburst hazard assessment.Although there has been a great deal of attention paid to coal and gas outburst, little attention has been paid to its special hazard assessment based on FTA method. Conceptual model of coal and gas outburst is presented according to comprehensive hypothesis of coal and gas outburst and the accident causality theory; based on FTA method, basic fault tree model of outbursts is constructed. Taking Daxing mine as an example, its fault tree model of outburst is established by combining geological-tectonic factors with the basic fault tree model of outbursts. After calculating the minimum cut set, the minimum path set and the structural importance degree, the mine's outburst path, endangerment degree, measures for prevention are evaluated to complete the special hazard assessment of gas outburst; to divide prediction regions of gas outburst hazard; so as to provide the scientific theory directions for disasters prevention of gas outburst accidents.