A Study on Nonlinear Heat Convection Analysis in Sediment Rocks Concerning to the Deep Underground Development

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As one of characteristics of sedimented soft rock it can be pointed out that the permeability of the materials are relatively high, and this sometimes gives rise to some problems such as in heat flows from the energy storage tanks in a soft rock mass. One of the features of weathering of soft rocks might be modeled by periodic cracks, which will affect heat and water flows in the rock mass as a whole when it contains the air bubbles in the fissures. Firstly, heat conducivity of rock mass was studied by considering periodic structure of sphere inclusion, and effects of water content and air content on the average heat conductivity were analytically studied when moisture movement was neglected.The model experiment was executed using a sand layr of 30cm in height, 30cm in width and 2.5cm in thickness. A heat source was placed at the bottom of the sand layr and the temperature distribution for two models with different permeability coefficient was measured in the way of heating. Then numerical analyzes were also made by finite element method, and effect of permeability of soils were studied. Good approximation was obtained by the numerical model, which shows a significant influence of convection by the heating of pore water. Another model was used to simulate the fracture zone in a rock mass and also effect of water flow on the heat conductivity was studied.