Dynamic Bearing Mechanism And Engineering Application In Interface Of Porous Saturated Medium And Elastic Medium Coupling System

Yuxi-Mohan Railway is the important part of the Trans-Asian Railways.The construction of Yuxi-Mohan Railway makes fully the regional advantages of Yunnan adjacent to Southeast Asia,and have significant role in improving the arrangement of Yunnan Railway net.Based on the newly-built YMZQ-16 section in Yuxi-Mohan Railway engineering,and considering the coupling of fluid-solid in soil medium,the interface contact,dynamic strength and stability in the engineering are studied.The special geological formation and more earthquakes are all discussed.The theoretical models suiting the on-site geological conditions are constructed,and the interface contact mechanism is also studied.The solving methods in engineering construction process is provided,and the theoretical foundation of engineering design is also given The detailed content of this dissertation is as follows:(1)According the practical characters of YMZQ-16 section in Yuxi-Mohan Railway engineering,the geological formation,engineering characters and environmental condition are studied.The on-site materials are collected,the on-site environment is simulated,and the load testing in laboratory is conducted.The material characters of water-saturated porous soil medium in hot and humid environment are tested.The research on the construction environment and the material characters can provide parameter support for further investigating the interface damage mechanism and giving the interface loading bearing mechanics.To ensure the reliability of the applied technique and materials,the strength at tunnel interface after construction is monitored,and the monitoring data is the desired results.The reliability of the models in this dissertation is validated,and technical support in the following derivation is given.(2)The dynamic model of partially broken tunnel embedded in the water-saturated porous soil medium is constructed,and the dynamic strength of the tunnel resulting from the partially broken region is studied.According to the dynamic Biot theory of water-saturated porous soil medium and wave motion theory in elastic medium,the partially broken tunnel model is given,and the elastic spring model in used to simulate the partially broken region.The mapping method and wave function expansion method are introduced to express the wave fields around the straight-wall tunnel.By satisfying the different boundary conditions of partially broken region and perfectly bounded region,the expanded coefficients are solved.The dynamic stress concentration factor around the straight-wall tunnel is obtained.Through numerical examples,the distribution of dynamic stress under different wave frequency and interface material properties around the tunnel is analyzed.(3)According to the characters of more earthquakes and more rivers of this engineering construction,the interface properties are introduced to study the dynamic response of underwater tunnel subjected to plane wave.The water in soil medium is simulated as non-viscous,compressible fluid.The elastic-slip interface model around the tunnel is used.The wave function expansion method is used to express the displacement fields,stress fields and fluid press in the water-saturated porous soil medium,free water in the rivers and tunnel lining.Numerical examples and in-site excremental data are given,and the effects of interface properties and embedded depth of tunnel on the dynamic stress around the tunnel are discussed.(4)The interface model of layered saturated porous soil medium and track plate is given to predict the vibration of water-saturated poroelastic ground induced by high speed train with a number of carriages.The model for the railway track consists of two rails with sleepers on water-saturated poroelastic half-space.The axle loading of the train is moving at a constant speed.The poroelastic half-space is characterized by Biot’s dynamic poroelastic theory,and the general solutions are obtained by Fourier transform.The solution of the steady-state deflection of the rails is obtained in a semi-analytic form,and the vertical deflection of foundation and its dependence on the velocity of the train is analyzed.The effects of the train speed,interface medium,damping property and the intrinsic permeability of the soil on the dynamic response are discussed.The effect of the number of sleepers under the rails is also examined.Through numerical examples,it is found that the settlement of sub-grade can be controlled by designing the parameters.