Research On The Occurrence Conditions Of Tectonic Stress Type Of Rock Burst

The rock burst in coalmines is always one of the difficult problems on rock mass mechanics and mine pressure, which is not solved in the theory and in practice. In recent years, there are a lot of rock burst occurrences in the deep mines of the Eastern China, which greatly threaten the mine production and safety, so it is necessary to research these rock burst occurrences systematically and deeply. Rock bursts are very different in occurrence intension and destruction degree. Up to now, most of researches are based on the condition of gravity field, although part of researches is relative to the tectonics stress field, the influence of geological structures and tectonics stress on rock burst occurrence was analyzed qualitatively. So, it is short of the quantitative research on the rock burst occurrence condition under the action of the tectonic stress.The tectonic stress type of rock burst occurrences in recent years are regarded as the research objects in this thesis, Many research methods, such as experiment in laboratory, field measures, theory analysis, and numeric simulation, are used to found mechanics models, simulate the occurrences of rock burst. Furthermore, the conditions of occurrences of rock burst are researched intensively, and the criteria of predicting rock burst are founded, which are used to predict the potential danger of rock burst in the coalfaces of non-excavating districts.The research works in this thesis are as follows:1. The critical pressure and conditions of drilling hole burst are determined through the physics experiment of drilling hole burst. Furthermore, the same experiment result as the physics experiment is gotten through numeric simulation experiment of drilling hole burst, and the characters of stress-drop and energy-release during the drilling hole burst are also discovered.2. The distribution of abutment stress, and its change rules with the mining depth, the character (strength and elastic module) and thickness of coal seam, the nature of overlying rock strata is researched through numeric simulation method under the damage state.3. Based on the measurement result of mining-induced stress, the stress distributions in coal seams and rock strata of different sizes of pillar are simulated under the action of tectonic stress. Then, the mechanics models of load condition simulating occurrence of rock burst arefounded.4. The occurrence of floor rock burst was simulated by numeric simulation method; thecharacters of occurrence of floor rock burst are discovered, and determination rules on floor rock burst are also put forward.5. The influence of side pressure coefficient on the occurrence condition of tectonic stress type of rock burst was researched; the concept of critical horizontal principal stress was put forward. Then the change rule of critical horizontal principal stress with side pressure coefficient is analyzed, the influence of critical horizontal principal stress on the occurrence of rock burst is also researched.6. The occurrence conditions of tectonic stress type of rock burst under the conditions of different thickness combination of hard and soft rock layers (coal seam) is calculated, and the concept of floor structure coefficient and the theory of floor coal and rock combination burst are put forward, and the basic contents of this theory are discussed.7. Through combined the occurrence conditions of underground rock burst and the simulation results of occurrence conditions of tectonic stress type of rock burst, two criteria of occurrence conditions of tectonic stress type of rock burst are firstly determined: one is that the angle between the orientation of tunnel (or coal face) and the orientation of maximum horizontal principal stress is equal to or greater than 70 degree; another is that the maximum horizontal principal stress is equal to or greater than critical horizontal principal stress.8. The Dongtan Mine is acted as the application example in this thesis. The distribution state of initial stress is researched by the measurem...