Numerical Simulation of Dynamic Response of Saturated Sand During Shield Construction

In order to study the disturbance of the liquefiable stratum caused by the vibration induced by construction of the shield machine,the construction process of the shield tunnel was simulated based on the finite difference software FLAC 3 D.A sinusoidal velocity boundary that simulates the vibration of shield construction is applied in the horizontal direction of the excavation surface,and dynamic response analysis is carried out to analyze the excess pore water pressure,acceleration,and vertical effective stress time-history curves.The research results show that in the liquefiable stratum,the vibration induced by shield construction will form a certain liquefaction area in the soil in front of the excavation face.The area has not developed to the ground.The area where the vibration induced by shield construction has a great influence on the excess pore water pressure of the soil is below the excavation surface.This area is vortex-shaped.The excess pore water pressure of the overlying soil layer on the excavation surface increases,and the vertical effective stress decreases.The horizontal vibration wave induced by shield construction has no obvious attenuation in the horizontal direction,but has obvious attenuation during the propagation to the ground surface.In the area where the peak value of soil acceleration is large,the soil liquefaction is serious.