Evolution Mechanism Of Damage Of Goaf In Deep Hard Rock Mines And Its Stability Control

Underground mining is the main way of Metal mines, because of long-term large-scale mining and lag treatment, a large number of goaf were generated which had been become one of major hazards of mines. Goaf stability is often difficult to judge as the complexity of its structure and surroundings, so that the effective measures could not made timely, especially deep mines. Therefore, Goaf stable or not is one of the key factors to ensure mining safety.Taking the goaf in deep mining of hard rock metal mines as the research object, to reveal the damage evolution mechanism and stability characteristics of goaf, taking mechanical experiments, theoretical analysis, numerical simulation and on-site monitoring as research methods to study on the Mechanical properties of goaf rokc mass under the complex stress path, goaf stability characteristics and instability mechanism, goaf system stability control and treatment.(1) Taking brittle rock from a typical deep mine as experimental material, the loading and unloading rock mechanics test was did. Mechanics and fracture characteristics of brittle rock under complex stress path were comparative analyzed. The energy evolution of the rupture process were studied based on the acoustic emission data and the mathematical model of the evolution of rock under complex stress path was built using least energy dissipation principle.(2) Variety of fractal characteristics of goaf were studies using fractal theory based on the fine probe data of goaf and the quantitative indicators system of goaf complexity was built. Sensitivity characteristics of single goaf stability were detailed researched to get quantitative relationship between complexity and stability and functional relationship between different factors and stable characteristics were built. The goaf were divided into narrow type of cubic type and surrounding disturbances law during their formation process were analyzed. Their roofs mechanical model based on elastic thick plates theory and clamped beams theory and fracture prediction model of long-narrow roof was built using damage fracture theory. These research results have been applied in the engineering.(3) Taking Chengchao Iron as engineering background, the instability analysis model under unloading path of goaf in the deep mines was built, and energy evolution were analyzed during the unloading process based on local energy release rate indicators. Energy instability criterion of rock was established based on the cusp catastrophe theory. The unloading instability mechanism of surrounding rock of goaf was revealed.(4) The evolution model of goaf system instability and catastrophic chain was built, then the energy effect mechanism of goaf system instability and catastrophic chain was proposed with the energy as a carrier and the evolution mathematical model of the energy chain effect was built. The energy evolution stages were divided and developing targeted control measures according to the different characteristics of different stages which have been applied in the engineering practice and have achieved good control effect. These researches provide a new theoretical basis for goaf stability controlling.