Major Hazard Source Identification Of Widespread Mined-out Area Instability

It is the first step of major accidents prevention and control that major hazard sources identify. The instability of widespread mined-out area is a typical major hazard sources in mine. Because of complexity of the problem and shortage of the research, the identification of this major hazard source is presently short of scientific systematic methods. Therefore, the study of widespread mined-out area instability identification is necessary.The study was combined with several scientific research projects. Such problems as disaster mechanism of widespread mined-out area instability, identifing methods and grading of major hazard sources were studied in this thesis, using theories in relation to safety science, rock mechanics, artificial intelligence, grey system, catastrophe and so on, and using techniques with regard to in-situ monitoring and prediction, numerical simulation and the like.The main work are as below. From the angle of rock mechanics, systematic analysis and research on the mechanism of mined-out area wall rocks instability were carried out. From the angle of safety science, the accident-cause theories of mined-out area wall rocks instability were approached. Neural networks technique which is belong to artificial intelligence, was used to identify the situation of widespread mined-out area instability. Combined with national science and technology project, identification methods of hazard source based on in-situ monitoring were discussed. Numerical simulation method was used to identify hazard source of widespread mined-out area instability. Hazard grading with regard to widespread mined-out area instability, which is a major hazard source in mine, was conducted.The main developments in this thesis are as follows.(1) It is the first time to research into the identification problem of major hazard source concerning widespread mined-out area instability systematacially. In view of the situation that some concepts and classification of major hazard sources and those in mine are ambiguous or inaccurate at present, the author gave their new definitions and classification of major hazard sources in mine.(2 ) Starting with process partition of widespread mined-out area instability, the creep properties of mined-out area wall rocks instability were researched thoroughly, and based on this, rheological model of widespread mined-out area instability was set up in the mode of combined model. Softening element was herein put forward and used, therefore, the accelerative creep properties of rock materials could be simulated conveniently.(3) An accident-cause model of perturbation-energy transfer (P-E model for short) about rock masses instability was brought forward, based on both perturbation occurs theory and energy transfer theory. It is thought that the model fits for other major disastrous accidents in mines equally.(4) By means of comprehensive analysis on abundant observation data, four typical coupling identification modes among stress, displacement and acoustic emission 3 parameters, were put forward, according to Kaiser effect which is an intrinsic property existing in theprocess of rock materials acoustic emission.(5) The limit exposed areas of mining zones were determined, according to the mutation conditions of energy release rate in the process of excavation mainly, and to the coditions of tensile stress, shear stress and rock masses yield. By means of programming interface software, the outcomes of finite element calculation could be get, and the index of energy release rate could be calculated, which solved the problem that general numerical simulation softwares can't do.(6) A method of aggregative index number to judge the unsafe condition of widespread mined-out area was put forward, on the basis of fully considering all sort of geologic factors and mining factors. The hazard of widespread mined-out area instability was divided into 4 levels in the method, and relevant aggregative index number was defined. It is a static classification method, and it has filled a gap of static classification method concerning widespread mined-out area instability.Through the study of this thesis, a set of perfecter identification theories and methods fitting for the major hazard source of widespread mined-out area instability were preliminary established, they will accelerate the study progress of other major hazard sources identification in mine, and advance the consummate of identification theories and standards of major hazard sources in our country. The study combined with projects, therefore, it not only has important theoretical meaning, but also has significant use value.