Study Of Shaking Table Test For Reinforced Cantilever Composite Retaining Structure

In the high-intensity seismic area,railway and highway serve as the lifeline of transportation,to ensure the stability of its subgrade engineering under the earthquake has important strategic significance.The cantilever type light retaining wall has good flexibility and anti-overturning ability,and is often used as a subgrade retaining structure.However,there are relatively few studies on the seismic performance of cantilever retaining wall and the interaction between wall and soil in high-intensity seismic regions,and even fewer studies on the seismic dynamic characteristics of reinforced cantilever composite retaining structures.In order to analyze the seismic performance of cantilever retaining wall and its reinforced composite bracing structure,and further improve the engineering application of the composite bracing structure,the shaking table model test of reinforced cantilever composite retaining structure was carried out under the rock-socketed foundation of coarse sand packing by using different magnitude of Indonesia and Kobe waves.The dynamic response of the acceleration of retaining wall and filling soil,and the distribution of the dynamic component of earth pressure behind the wall and the total earth pressure are analyzed and studied.The main research contents and results of this thesis are as follows:(1)This paper summarizes the similarities and differences of seismic design codes of various domestic industries on seismic design methods of structures and related contents of seismic action.The differences in the selection of fortification level and the level of fortification target of building structure,bridge structure and structure are compared and analyzed.The differences of the key parameters of the design response spectrum and the methods of considering the damping ratio are described.The seismic design methods of building considering vertical seismic action in various industries are summarized.The ideas and influencing factors of seismic earth pressure calculation of retaining structures are summarized.(2)For the cantilever retaining wall,the time-history response data of the wall-soil interaction and acceleration are obtained by the laboratory shaking table model test.The results show that under different ground motions,the different elevation fills behind the cantilever retaining wall have a certain dynamic amplification effect on the ground motion peak acceleration,and the dynamic amplification effect of the wall top is more significant.The amplification coefficient of filling acceleration does not increase with the increase of the magnitude of ground motion,which is similar to the phenomenon of "magnitude saturation".The dynamic component intensity distribution of the earth pressure behind the wall is more consistent,which has a significant effect on the total earth pressure under the seismic condition and is the main controlling factor of the total earth pressure intensity.The theoretical calculation value of the seismic earth pressure intensity criterion of the wall under different ground motion magnitudes is smaller than the experimental measured value.Under the seismic conditions,the total earth pressure of the wall back increases with the increase of the ground motion magnitude,and the position of the action point increases with the increase of the seismic magnitude.(3)Based on the experimental research and analysis of the cantilever retaining wall model,the effect of the reinforcement is discussed through the two different working conditions,the traditional combined structure and the new coordinated structure.The test proves that the traditional combination structure of reinforcement has not exerted the effect of reinforcement under the action of earthquake.However,the dynamic component of the back pressure of the new coordinated structure is obviously reduced compared with the traditional combined structure.Because of its flexible deformation coordination deformation makes the ribbon to share the load with the soil,which greatly exerts the ribbing effect.It indicates that the key for reinforced composite structure to play the role of reinforcement belt is that the cushion has a large stiffness difference from the soil behind the wall.The new coordinated structure has a small total earth pressure at the back of the wall with the same wall height and the same magnitude of earthquake,and the position of the action point is slightly lower than that of the traditional combined structure.For the seismic design of the retaining wall which is prone to overturning damage,it is more advantageous to adopt the new coordination structure.