地铁荷载下饱和软黏土累积变形特性

Accumulative Deformation Characteristics of Saturated Soft Clay Under Subway Loading in Shanghai

摘要:

针对地铁循环荷载作用下饱和软黏土的变形特性,对上海地铁2号线静安寺站附近的饱和淤泥质黏土进行GDS(global digital systems)循环三轴试验.试验结果表明,振动次数一定时,累积塑性应变随动应力幅值的增大而增大,随荷载频率的增大而减小;采用正交设计法安排试验,充分考虑了振动次数、荷载频率、动应力幅值以及其两两交互作用等因素对土体累积变形的影响,结合数理统计分析法建立了影响土体变形的影响率及评价方法.研究结果显示,影响地铁隧道轴线变形的主要因素是动应力幅值,而荷载频率与振动次数的交互作用可以忽略,此研究成果对地铁隧道设计具有重要的参考价值.

Abstract:

Through the dynamic triaxial tests for the saturated silt soil around the tunnel of the Jing’an Temple Station,the deformation analysis is made on the saturated soft clay under the subway train loading.The results show accumulative plastic strain increases with larger amplitude of dynamic stress and less loading frequency with the same vibration times.Orthogonal design is used to arrange the experiment by taking a full consideration of the factors which have effect on the accumulative deformation,such as vibration times,the loading frequency,the amplitude of dynamic stress,and the interaction between one factor and the other.The mathematical statistics approach is established and is used to analyze the influence rate of the deformation.It also shows that main factor which affects axial deformation of subway tunnel is the dynamic stress amplitude and the interaction function on vibration frequency and vibration times can be ignored.The study offers a valuable reference to the design of subway tunnel.