【作者】 刘涛；

【导师】 邵珠山；

【作者基本信息】 西安建筑科技大学 ， 岩土工程， 2017， 硕士

【摘要】 随着地下轨道交通的快速发展,地铁列车荷载引发的土体振动和变形成为影响地铁运营安全的重要因素。目前关于动荷载作用下黄土动力特性和变形研究多基于地震或震陷。与地震荷载相比,地铁列车荷载具有小幅值、长持续时间等特点,而对于地铁列车荷载长期作用下黄土的动力特性和变形研究相对较少。基于以上原因,本文以西安地铁四号线为工程背景进行了以下研究:1)通过振动三轴试验,研究非饱和黄土的动应力—动应变和动应力—残余应变关系,得到:在同一动应变之下围压、固结应力比越高,动应力幅值越大。2)通过循环三轴试验,得到随着动应力幅值的增加,非饱和黄土残余应变也随之增加。3)ABAQUS数值分析结果表明:竖直方向振动响应大于水平方向振动响应;地层的振动响应大于地表振动响应;地表振动响应在距隧道轴线一定水平距离会出现“局部放大”现象;地层振动响应在地表附近和隧道邻近区域出现了“局部放大”现象;荷载频率越低,地表的振动响应越大;在隧道邻近区域之外的土体,频率越低振动响应越大;隧道邻近区域的土体,振动响应规律各不相同,高频荷载的加速响应较大,低频荷载的速度响应较大,中间频率荷载的位移响应较大;速度为某一特定值时,振动响应最大。4)使用Chai-Miura模型结合分层总和法研究了塑性沉降的累积效应,得出:隧道邻近区域土体的静动偏应力分布会发生突变;在地铁行车荷载作用初期,地表沉降增长很快,增长速度随着地铁行车荷载循环作用次数的增加而逐渐变缓,沉降稳定时,地面的沉降最大值为18.0mm,隧道下方的沉降为1.07mm;塑性变形主要发生在隧道邻近区域之中。更多还原

【Abstract】 With the rapid development of underground rail traffic,the deformation and vibration of soil caused by subway train load become an important factor affecting the safety of metro operation.At present,the study about dynamic characteristics of loess under dynamic load and deformation mostly based on the earthquake,but the study of dynamic characteristics and deformation under the long-term train load are relatively few.Based on the above two points,this paper make the following research:1)Through vibration triaxial test,study relations of dynamic stress,dynamic strain and dynamic stress,residual strain in unsaturated loess area.we learn that under the same dynamic strain the higher confining pressure,consolidation stress ratio,the greater the dynamic stress amplitude.2)Through the cyclic triaxial test,the residual strain of unsaturated loess will increase with the increase of the amplitude of dynamic stress.3)Using ABAQUS numerical to analyze we can learn that vertical direction vibration response is greater than the horizontal vibration response;The surface vibration response well occur " Local amplification " phenomenon when there is some distance away from tunnel axis;Ground vibration response near the surface and tunnel adjacent area appears the phenomenon of "local amplification;the lower the load frequency,the greater the vibration response of the earth’s surface;Soil outside the tunnel adjacent area,the lower frequency vibration response is;Different tunnel adjacent area of the soil,the vibration response is not the same,the acceleration response of the high frequency load is bigger,the velocity response of low frequency load is bigger,the intermediate frequency load displacement response is larger;At the rate of a certain value,the vibration response is the largest4)Through the Chai-Miura model combining with layered summation method to calculate the surface accumulated settlement.We can learn that when the soil close to tunnel,the static and dynamic deviatoric stress distribution will mutate;At the beginning of the metro vehicle load,soil sedimentation velocity increase quickly.When settlement gradually stable over time with the increase of cycle number,maximum value subsidence of the ground is 18.0 mm and the settlement at the bottom of the tunnel is 1.07 mm.Plastic deformation mainly occurs in the adjacent tunnel area.更多还原