Based on specific geology and mining conditions of certain coal working face in China, a series of numerical models under different unconsolidated layers thickness were respectively established by employing FLAC3D. Th...Based on specific geology and mining conditions of certain coal working face in China, a series of numerical models under different unconsolidated layers thickness were respectively established by employing FLAC3D. The relationship between the unconsolidated layers thickness and surface movement laws was studied. Maximum surface subsidence, Maximum horizontal displacement and surface subsidence degree were obtained. Contours of surface subsidence/horizontal displacement and curves were drawn. Some laws of surface subsidence/horizontal displacement were analyzed. The role of the unconsolidated layers in surface subsidence was revealed. It is significant to predict surface subsidence of thick unconsolidated layers for coal mine and take effective measures to control surface subsidence.展开更多
A review of former studies on the onset of sediment movement under wave action reveals that the Shields criterion obtained in unidirectional steady flow can also be applicable to oscillatory unsteady flow when the bou...A review of former studies on the onset of sediment movement under wave action reveals that the Shields criterion obtained in unidirectional steady flow can also be applicable to oscillatory unsteady flow when the boundary layer is the same. In this paper, through comparison of different boundary layers in wave and steady flow conditions, a new criterion is presented which can be used to predict the threshold of sediment movement Linder wave action. The criterion curve shows good agreement with the experimental data.展开更多
According to the problem during mining coal seam with high gas and its control, the theory numerical calculation of gas and strata movement law caused by protection layer mining was studied, with the background of Sna...According to the problem during mining coal seam with high gas and its control, the theory numerical calculation of gas and strata movement law caused by protection layer mining was studied, with the background of Snake Mountain coal mine. First of all, the basic principle of fluid(gas)-solid coupling was briefly described, and a three dimensional model was established by FLAC software. Secondly, the calculation parameters of fluid-solid coupling were obtained based on the measured data, and the numerical calculation of sublevel mining was carried out in turn. Lastly, initial stress state, gas movement law, deformation law of pore pressure and movement characteristics of rock strata were studied, respectively. The results show that the gas and pressure were greatly reduced with the advance of 4 coal seam working surface, as well as the constant increase of area of goaf. Facilitating gas and the stress were gradually penetrated and released to goaf during the whole process of mining. The gas pressure, the aggregation degree and the surrounding rock pressure of the 1 coal seam and the 3 coal seam were greatly reduced.展开更多
Most of the earthquake faults in North-East India, China, mid Atlantic-ridge, the Pacific seismic belt and Japan are found to be predominantly dip-slip in nature. In the present paper a dip-slip fault is taken situate...Most of the earthquake faults in North-East India, China, mid Atlantic-ridge, the Pacific seismic belt and Japan are found to be predominantly dip-slip in nature. In the present paper a dip-slip fault is taken situated in an elastic layer over a viscoelastic half space representing the lithosphere-asthenosphere system. A movement of the dip-slip nature across the fault occurs when the accumulated stress due to various tectonic reasons e.g. mantle convection etc., exceeds the local friction and cohesive forces across the fault. The movement is assumed to be slipping in nature, expressions for displacements, stresses and strains are obtained by solving associated boundary value problem with the help of integral transformation and Green’s function method and a suitable numerical methods is used for computation. A detailed study of these expressions may give some ideas about the nature of stress accumulation in the system, which in turn will be helpful in formulating an earthquake prediction programme.展开更多
基金Project(2007BAK28B03)supported by the National Eleventh-Five Year Research Program of ChinaProject(2010YD05)supported by the Fundamental Research Funds for the Central UniversitiesProject(200911036)supported by the Ministry of Land and Resources Research Special
文摘Based on specific geology and mining conditions of certain coal working face in China, a series of numerical models under different unconsolidated layers thickness were respectively established by employing FLAC3D. The relationship between the unconsolidated layers thickness and surface movement laws was studied. Maximum surface subsidence, Maximum horizontal displacement and surface subsidence degree were obtained. Contours of surface subsidence/horizontal displacement and curves were drawn. Some laws of surface subsidence/horizontal displacement were analyzed. The role of the unconsolidated layers in surface subsidence was revealed. It is significant to predict surface subsidence of thick unconsolidated layers for coal mine and take effective measures to control surface subsidence.
文摘A review of former studies on the onset of sediment movement under wave action reveals that the Shields criterion obtained in unidirectional steady flow can also be applicable to oscillatory unsteady flow when the boundary layer is the same. In this paper, through comparison of different boundary layers in wave and steady flow conditions, a new criterion is presented which can be used to predict the threshold of sediment movement Linder wave action. The criterion curve shows good agreement with the experimental data.
基金Funded by the Open Research Foundation of Key Laboratory of Safety and High-efficiency Coal Mining,Ministry of Education(Anhui University of Science and Technology)(No.JYBSYS2015201)the National Natural Science Foundation of China(No.51574122)the Natural Science Foundation of Hunan Province,China(No.2017JJ2082)
文摘According to the problem during mining coal seam with high gas and its control, the theory numerical calculation of gas and strata movement law caused by protection layer mining was studied, with the background of Snake Mountain coal mine. First of all, the basic principle of fluid(gas)-solid coupling was briefly described, and a three dimensional model was established by FLAC software. Secondly, the calculation parameters of fluid-solid coupling were obtained based on the measured data, and the numerical calculation of sublevel mining was carried out in turn. Lastly, initial stress state, gas movement law, deformation law of pore pressure and movement characteristics of rock strata were studied, respectively. The results show that the gas and pressure were greatly reduced with the advance of 4 coal seam working surface, as well as the constant increase of area of goaf. Facilitating gas and the stress were gradually penetrated and released to goaf during the whole process of mining. The gas pressure, the aggregation degree and the surrounding rock pressure of the 1 coal seam and the 3 coal seam were greatly reduced.
文摘Most of the earthquake faults in North-East India, China, mid Atlantic-ridge, the Pacific seismic belt and Japan are found to be predominantly dip-slip in nature. In the present paper a dip-slip fault is taken situated in an elastic layer over a viscoelastic half space representing the lithosphere-asthenosphere system. A movement of the dip-slip nature across the fault occurs when the accumulated stress due to various tectonic reasons e.g. mantle convection etc., exceeds the local friction and cohesive forces across the fault. The movement is assumed to be slipping in nature, expressions for displacements, stresses and strains are obtained by solving associated boundary value problem with the help of integral transformation and Green’s function method and a suitable numerical methods is used for computation. A detailed study of these expressions may give some ideas about the nature of stress accumulation in the system, which in turn will be helpful in formulating an earthquake prediction programme.
