Research On Ground Stress Distribution Charcteristics And Its Effect On Roadway Surrounding Rock Stablity

Ground stress is the essentially force which arouses deformation and damage in a variety of underground geotechnical engineering. With mining exploration at great depth, the surrounding rock instability and rock burst aroused by ground stress are more and more serious, so, ground stress has become a technical issues needed in-depth study. In this paper, the distribution of ground stress field and its effect on the stability of surrounding rock were studied systematically by using ground stress measurement technology, modern mechanical theory, artificial neural network numerical simulation analysis, and achieves the following research results:(1) The causes and influencing factors of stress field were summarized, and in Huozhou coal area, the stress field was analyzed macroscopically by using the theory of geomechanics, analytical method of earthquake focal mechanism solutions and GPS survey of crustal deformation. In the mining area and adjacent regions, the evolution process of the ancient earth's crustal stress field was reproduced. In macroscopic view, the type of stress field belongs to horizontal tectonic stress field and the main compressive stress superiority trend is in the NEE～NWW direction, and can provide evidence for the correctness of the stress measured. Combined with the actual production of the mining area, the stress measured points were arranged systematically, and the stress of Huozhou mining area was measured with stress relieving method. Then, the distribution of the whole mining area was obtained by theoretical calculations and mathematical statistics.(2) Based on the theory of geomechanics, the model of regional stress field was established, and the elasticity analysis was carried out with different boundary conditions, and the expressions of stress component were obtained. Combined with the measured data, the Caocun coal mine and Xinzhi coal mine as the study areas, an inverse calculation of the stress field was carried out by using the finite element numerical simulation, and the distribution of stress field was analyzed in great detail. The results show that the stress field relies mainly on horizontal stress, and due to differences in geological structure and lithology and other factors, the range of maximum principal stress is larger, and there are relatively high stress zones.(3) Based on the field measured data of stress field, a combination artificial neural network model (PSO-BP model) of stress field prediction was established, with particle swarm optimization algorithm. Giving full play to the self-learning ability of neural network, the nonlinear mapping between relevant parameters of measuring points and the corresponding stress was established, and got the successful forecasting to the ground stress in Liyazhuang coal mine and Caocun coal mine.(4) Based on the geological data and mechanical parameters of rock by measured, by using FLAC3D, the effect of the angleαbetween the axial location of roadways and direction of maximum principal stress on stress, displacement and plastic zone in roof and floor was analyzed systematically. The results show that the direction of maximum principal stress has a significant effect on the stability of surrounding rock, and whenα> 45°, the stress, displacement and plastic zone in surrounding rock change increased suddenly. The statistical analysis of the actual destruction of underground roadway also confirmed the conclusions of the study.(5) For fully considerating the effect of ground stress on roadway surrounding rock stablity, Dynamic bolt supporting design method based on ground stress measurement is proposed. Based on the results of the study, the bolt support of mining area 10 with expansion broken rock and high stress in Caocun coal mine was designed, and achieved satisfactory supporting effect.