Study On The Mechanical Characteristic Of Frozen Soil Wall And Inclined Shaft Lining In Saturated Sand Stratum

It is have great theoretical significance and engineering application value to study the mechanism of the combined action of freezing wall and shaft wall in an artificially frozen inclined shaft with water-rich sand stratum.In this paper,based on the artificially frozen inclined shaft project in a coal mine in northern Shaanxi,the research work was carried out through indoor physical and mechanical tests,indoor similar material physical model test,theoretical analysis,field measurement and finite element simulation.The physical and mechanical tests of frozen sand under different freezing temperatures were measured,including:saturated volumetric weight of sand,saturated moisture content of sandy soil,specific heat capacity of frozen soil,thermal conductivity of frozen sand,cohesive force of frozen sand,angle of internal friction of frozen sand,modulus of elasticity of frozen sand and uniaxial compressive strength of frozen sand.At the same time,the uniaxial compression failure of frozen sand is analyzed based on the acoustic emission test,gives the acoustic emission characteristics of artificial frozen sand under different freezing temperatures.Studied on the mathematical model of the temperature field,stress field and seepage field distribution of the frozen wall under the condition of a single freezing pipe.Given the mathematical model for the temperature field,stress field and seepage field distribution of frozen wall under a single freezing pipe,and based on the superposition principle of the field given the mathematical model for the distribution of temperature field,stress field and seepage field of frozen wall under multiple freezing pipes.Given the coupling calculation model of the heat-moisture-stress fields,based on that,analyzed the interaction mechanism of outer wall-frozen wall-unfrozen sand.Given the formula for calculating freezing pressure and the calculation formula of the inclined frozen wall thickness,that is based on the heat-moisture-stress fields.Completed model test of mechanical characteristics of the interaction between the frozen wall and the inclined shaft wall by used the self made simulation system of the inclined shaft freezing.Analyzed the law of freezing wall temperature,freezing pressure and pore water pressure,the test results show that:in the active freezing period,with the increases temperature of freezing wall the freezing pressure and the horizontal freezing pressure increase rapidly.When the freezing period is changed from the active freezing period to the maintenance of the freezing period,the vertical freezing pressure and horizontal freezing pressure of the frozen wall do not change basically.When the freezing wall is negative temperature,the pore water pressure is decreases with the decrease of the freezing wall temperature,and the pore water pressure increases when the freezing wall temperature rises.According to the test results,the paper gives fitting formula of the freezing wall temperature-time,the fitting formula of frozen-heave force-freezing wall temperature,and the fitting formula of frozen-heave force-time.Used the FLAC~3DD software,analyzed the interaction between the frozen wall and the inclined shaft wall,given the law of temperature field,freezing pressure and pore water pressure of frozen wall under different buried depth.Comparative the results of numerical simulation and model test we can know that:the changing trend of freezing wall temperature,freezing pressure and pore water pressure in the active freezing period are basically the same,which prove that the mechanical characteristic model test of the interaction between the frozen wall and the shaft wall designed in this paper is reasonable and reliable.Verified the formula for calculating the thickness of frozen wall of inclined shaft,the results show that the formula is reasonable and reliable,and it can meet the design requirements.Analyzed the field measured results of the interaction between the frozen wall and the shaft wall of the inclined shaft,mainly includes the law of freezing wall temperature,freezing pressure,wall stress,concrete strain and pore water pressure,according to the measured results verified the freezing pressure calculation formula,the frozen wall temperature time fitting formula,freezing wall temperature and frost heave force fitting formula and frost-heave force time fitting formula.The results show that:the fitting formula of the freezing wall temperature-time,the fitting formula of frozen-heave force-freezing wall temperature,and the fitting formula of frozen-heave force-time is reasonable and reliable,and it can meet the design requirements.According to the theoretical analysis,model test,numerical simulation,field measurement results and the interaction of the frozen wall and shaft,used the I-steel shed+reinforced concrete brickwork for supporting structure.Analyzed the load model of the inclined shaft wall and given the calculation method for the inclined shaft loads.The internal force calculation model of the inclined shaft wall and the thickness of shaft wall are given.Put forward the construction scheme for the freezing method of inclined shaft and it can provide theoretical support for the design and construction of inclined shaft.