Coupled Thermo-(Hydro)-Mechanical Dynamic Responses Of Soil And Lining System

The lining structures are always used as supporting structures to apply in the underground engineering,e.g.thermal pipelines,subway tunnels,pertrol and natural gas transportation pipelines and ocean tunnels.These underground structures are commonly subjected to high temperatures and impact loads,etc.Therefore,the thermoelastic dynamic response of soil-lining system under the heat source or mechanical source has attracted much attention of scholars.However,there is a limited work about the coupled thermoelastic response and the coupled thermo-hydro-mechanical dynamic response of soil-lining system.In this work,the interaction between the soil and the lining was considered,and the thermoelastic dynamic response of the elastic soil and the lining,the thermal diffusive effect of the lining-soil system with the deeply buried circular tunnel,the coupled thermo-hydro-mechanical response of the saturated soil and the cyclindrical lining system,the thermophysical property test of geotechnical materials under variable temperature load and the coupled thermo-hydro-mechanical dynamic response of the lined tunnel in saturated soil with temperature-dependent were studied.The main contents of the thesis are as follows:1.The thermal contact resistance and the elastic wave impendence at the interface are considered,and the discontinuous interfacial model of the soil and the lining at the interface was established.The soil and the lining were regarded as the thermoelastic medium with GL model,the coupled thermoelastic dynamic response of the elastic soil and the lining system were investigated.By using the Laplace transform and its inverse transform,the analytical solution for the dynamic response of the lining-soil system was obtained in the time domain.The influences of thermal contact resistance,elastic wave impendence ratio,thermal conductivity ratio and heat capactity ratio on the responses were studied.2.Considering the thermal diffusion effect,analytical method was employed to study the thermoelastic dynamic response of deep-buried circular tunnel lining-soil system under heat source and mechanical load.The soil and lining were regarded as homogeneous elastic media.Based on the generalized thermal diffusion theory and the classical thermal elasticity theory,the thermoelastic dynamic response of a soil-lining system was solved by Laplace transform and Helmholtz decomposition.By using continuity boundary conditions,the corresponding numerical solution was obtained by adopting Laplace inverse transformation.The calculation results were compared with those without lining and without the consideration of diffusion effect.The effects of lining and soil properties and their geometric parameters on the temperature gradient,displacement,stress and chemical potential of the system were analyzed under thermal,mechanical and chemical coupling.3.This study deals with the coupled thermo-hydro-mechanical dynamic response of a cylindrical lined tunnel in a poroelastic medium when subjected to the joint action of a thermal and mechanical source.With the fractional-order thermoelasticity theory,the fully coupled thermo-hydro-mechanical dynamic model was presented based on the equations of motion,fluid flux,and fractional heat conductivity.The soil was regarded as a saturated porothermoelastic medium and solved by the generalized energy equation of porothermoelasticity with fractional derivative.Furthermore,the lining structure was equivalent to the elastic material by the theory of thermoelastic shell.The study derives the temperature increment,displacement,stresses,and pore water pressure by using the differential operator decomposition method and the Laplace transform method.The influences of the fractional derivative parameter on the responses were discussed and the numerical results compared with the results of the theory of saturated porous medium and the cavity without lining.4.Regarding the lining and rock as flexible porous materials and saturated porous medium,respectively,and the thermo-hydro-elastodynamic responses of a partially sealed circular tunnel in saturated soils subject to internal thermal water pressure were investigated by the fully coupling thermo-hydro-elastodynamic model for saturated porous medium.By using the method of Laplace transform,the temperature increment,displacement,pore pressure and stress of saturated rock are obtained.The tunnel is assumed to be partially sealed,the partially permeable conditions on the boundary of tunnel are established by using the Darcy' law.A stress coefficient depending on the volume fraction of pore fluid is quoted to establish the stress coordination conditions on the boundary of tunnel,and the unknown coefficients in the expressions are determined.By using a Crump method of the inverse Laplace transform,the numerical solution to the problem is presented.Numerical results are shown graphically and the results obtained are analyzed.5.The thermal deformation images of three typical tunnel lining-rock materials(concrete,granite and clay)under the temperature change process(20 °C ? 200 °C)are collected by industrial camera at interval,and then thermal deformation of these materials were obtained by digital image correlation method.The thermal deformation information of tunnel lining-rock materials under variable temperature was studied.The test results show that the thermal deformation of concrete and granite has certain local non-uniformity and is aggravated with the increase of temperature.The surrounding clay of the lining was easily cracked under high temperature to form cracks,which in turn changes the heat transfer and stress characteristics of the lining structure;the thermal expansion coefficient of concrete and granite increases with the increase of temperature,and the variation equation can be obtained by digital image correlation method.6.The coupled thermo-hydro-mechanical dynamic response of a cyclindrical lined tunnel in the saturated soil with temperature-dependent subjected to a heat source was studied.It is assumed that the thermophysical parameters are linearly related to the temperature increment,the coupled thermo-hydro-mechanical dynamic model with temperature-dependent was established.The soil and the lining were regarded as the saturated porous thermoelastic medium and thermoelastic medium,the time domain solutions of the saturated soil and the lining system were obtained by the Kirchhoff and Laplace transform methods.The corresponding numerical solution was obtained by the Laplace inverse transformation.The expression of the undetermined coefficient was determined by the discontinuous interfacial condition.The influences of the thermophysical coefficient ratio and elastic wave impedance ratio of the soil and the lining on the response were discussed.