Research On Interaction Between Saturated Soil And Lining Under Moving And Transient Loads

In recent years,with the rapid development of China's economy and the increasingly rapid urbanization process,urban transportation is facing tremendous pressure.In order to improve urban traffic congestion and ease the denseness of traffic lines,major cities have actively launched a series of subways and tunnels,but the effects of the dynamic loads on the tunnel lining and the surrounding soil on the tunnel internal and external dynamic loads cannot be ignored.Therefore,it is of great significance to study the interaction between soil and lining under dynamic loading.This paper uses theoretical analysis and numerical examples to carry out related research on the interaction between soil and lining under moving and transient loads.The specific research work includes the following points:(1)An analytical closed solution of the dynamic response of a circular lining tunnel in a layered half-space under the action of a moving point source is given using the wave function method.The circular lining tunnel is simulated as a hollow cylinder,and the soil around the tunnel is simulated as containing a circle.The half-space with the shape of a hole,the lining structure and the soil are all viscoelastic media.The transformation between plane wave and cylindrical wave vector wave functions is used to solve the conversion problem of rectangular coordinate system and cylindrical coordinate system.Finally,the entire model is solved by applying the displacement and stress boundary conditions at the ground surface and the tunnel-soil interface.This analytical solution can provide a set of efficient and accurate analysis methods for the environmental vibration problems of subway trains,and can be used as a benchmark solution for other numerical methods.(2)The viscoelastic boundary model is introduced,and the effects of the radial stiffness coefficient Kr and the damping coefficient Cr on the viscoelastic boundary on the radial displacement and stress of the saturated soil and lining under three transient load forms are studied.Based on the Biot wave theory,a wave equation for saturated soil is established,the lining is regarded as an elastic medium,and the governing equation of the lining is established.The Laplace transform and numerical inverse transform methods are used to obtain the solutions in the Laplace transform domain and time domain.The viscoelastic boundary parameters under degraded conditions are compared with the radial displacement and stress of the soil under perfect bonded boundary conditions.The solutions under viscoelastic boundary conditions are verified.The effects of different K_r and C_r values on the dynamic response of saturated soil and lining structures under sudden load,step load and triangular impulse load are analyzed.(3)Based on the VB mixture theory,unsaturated soil is regarded as quasi-saturated porous media,the soil mass,lining displacement and stress response under different saturation in quasi-saturated soil are compared and analyzed,and the influence of different contact boundary conditions between lining and soil mass on the dynamic response is studied.The wave equation of unsaturated soil is simplified to the dynamic governing equation of quasi-saturated soil and transformed into displacement expression.Laplace transform is used to solve the quasi-saturated soil and lining wave equation in the transformation domain.The unknowns of each expression are obtained,and numerical examples are used to analyze and discuss the law of lining and soil vibration response under different soil saturations,which can provide a theoretical basis for the dynamic analysis of the interaction between soil and lining under transient loads.