| Artificial freezing method is one of the formation water proof methods widelyused at home and abroad. For the effect of water seepage and the joint surfaces infractured rockmass, reaearch on the distributions of temperature and flow fields underseepage condition has become an important topic which should be urgently solved inartificial freezing engineering. The coupled mechanism of freezing temperature fieldand flow fieldis systemically studied by theoretical analysis and numerical simulationmethods. And the effects of flow velocity in joint surface and the aperture, orientationangle and the roughness of joint surface on temperature and flow fields ismainlyanalysised. The following resultsare obtained:(1) According to the practice of artificial freezing shaft sinking engineering, themathmetical model of the problem of artificial freezing in fractured rockmass underseepage condition is built. Based on the theories of irreversible thermodynamics andcontinuum mechanics, the THM coupling control equations are obtained withconsidering the phase change during the process of freezing. And the variation laws ofphysical parameters (volume heat capacity, thermal conductivity and permeabilitycoefficient etc.) with temperature are given.(2) The caculation model of the freezing temperatue and flow fields in fracturedrockmass with the fissure ratio obeys the Weibull distribution was built by thenumerical generation method. Then the effects of Weibull distribution parameters onthe freezing temperature and flow fields in fractured rockmass were analysised. Andthe process of artifically frozen construction wassimulated, the results showed that thecharicteristics of joint surfaces play a key role in the quality of artificial freezingengineerings.(3) The two holes freezing model of fractured rock mass containing joint surfacewas built.And the effects of flow velocity in joint surface and the aperture andorientation angle of joint surface on the closure time, thickness and developmentvelocity of frozen wall and the distribution law of flow field in artificially frozenground with water seepage were studied, the results showed that the flow velocity injoint surface influence the temperature and flow fields most, then the aperture of jointsurface and the orientation angle of joint surface the least.(4) The flow control equation of joint surface in fractured rockmass is given.Then the aperture at each point on joint surface is generated by numerical generationmethod, and the corresponding roughness is calculated either. Based on two holes freezing model of fractured rock mass containing joint surface, the effects of the meanaperture and the roughness of joint surface on the closure time, thickness anddevelopment velocity of frozen wall and the distribution law of flow field inartificially frozen ground with water seepage were analysised. |
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