| Thermal-hydro-mechanical(THM) coupling effect of soft clay when subjected to explosive loading involves seepage flow mechanics, soil dynamics, heat transfer theory, etc. and depends on various and complicated factors. The physical and mechanical behaviors of soft clay posterior to explosion reveal deformation and damage of the solid and the liquid phases under temperature field, and their interaction with seepage, which can be described as coupling effect. The thesis aims at presenting a THM coupling dynamic model for a saturated porous medium with special emphases on the THM coupling effect computation model of soft clay, the in-situ explosive experiment in soft clay, and numerical simulation on the interaction between soft clay and tunnel after explosion. Main researches and achievements are summarized as follows:Based on the THM coupling effect, the classical Fourier heat equation is modified. Considering the fact that the compressibility of liquid and solid, thermal diffusion, thermal conduction and temperature change affect seepage flow velocity, a THM dynamic response model of saturated porous media is formulated. In the absence of heat effect, the Biot model is recovered.Dynamic response of a semi-infinite saturated porous elastic medium due to an internal point thermo-mechanical impact is analyzed by using the THM dynamic response model. The Hankel integral transform method is used to obtain an analytical solution in integral form of the stress, displacement and pore pressure in soil when subjected to simple harmonic loading. The vertical displacement and the pore pressure of clay are also discussed and compared with those derived by the porous elastic model.The quasi-static and elasto-plastic theories are employed to analyze the relationship between the radius of an explosive cavity in soft clay and its physical, mechanical properties as well as the parameters of dynamite. Considering the variation tendency of thermo-shock with time, the THM dynamic responses of a spherical cavity and a cylindrical cavity in an isotropic elastic medium are studied by means of the Laplace integral transform method. Moreover, the influences of the thermo-osmosis and osmosis coefficients on THM dynamic response of a spherical cavity in an isotropic elastic medium are discussed. A comparison of numerical results using the THM coupling dynamic model and the thermo-elasticity theory is made.Taking account of the viscoelasticity of soft clay, the relaxation function is introduced to handle the THM dynamic response of soft clay. Using the Laplace transform technique, temperature increment, stress, displaceme nt and pore pressure are obtained directly when subjected to thermo-mechanical harmonic loading. In addition, the influence of the relaxation function on the THM coupling dynamic response of soft clay is indicated.Under the assumption that pressure induced by inner explosion occurring in the tunnel is uniformly distributed on the lining surface, the THM coupling dynamic response of soft clay tunnel subjected to thermo-mechanical harmonic loading is studied. By introducing relative permeability, the influences of the relative stiffness and relative permeability of lining and clay on the dynamic response of soil-structure are explored.Experiment of in-situ explosion in soft clay was made. Blast pressure, pore water pressure, explosion temperature, etc were measured and relevant data were obtained. The attenuation form of blast waves in saturated soft soil is derived and their propagation’s law is further elucidated.Under the condition that soil is understood as an ideal elasto-plastic material, the Drucker-Prager model is employed to establish the 3D numerical computational model of soil and tunnel via ABAQUS FEM software. The dynamic response curves such as stress, acceleration and displacement versus time for blast wave lining surface are analyzed. Also, the dynamic response of soil subjected to explosive loading is investigated. |
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