运营期单洞双线地铁隧道周围土体动力响应模拟分析

发布时间：2018-04-05 05:14

本文选题：地铁　切入点：单洞双线隧道　出处：《南京大学》2015年硕士论文

【摘要】：地铁列车运行引发周围土体动力响应,具体包括加速度、应力、应变、位移、孔隙水压力等。越江地铁隧道所穿越地层工程地质条件复杂,地铁运行所引起的土体动力响应对土体工程性质可能产生的影响不容忽视。目前,国内外对单洞双线地铁隧道周围土体动力响应研究尚未系统开展。南京地铁10号线过江段为国内首条穿越长江的单洞双线盾构隧道,本文以该区段近江北大堤断面为例,采用PLAXIS 2D,对地铁列车运行引起隧道周围土体的动力响应进行了有限元模拟；同时,对隧道下卧层砂土可液化性进行了分析,得到了以下结论：(1)列车动力作用使土体的动力响应呈周期性变化。在列车通过的时间内,出现了24个峰值,对应于轮轨接触过程中单趟列车的12个转向架、24个轮对的冲击作用。(2)在列车动荷载作用的时间内,隧道下卧层、拱腰位置,加速度随着距隧道中心距离的增加而衰减。地表加速度在传播过程中,水平方向距离隧道中心10m处出现一个极大值。(3)单线工况隧道基底以下动应力的最大值为3.6kPa,双线工况隧道基底以下动应力最大值约为7.2kPa,双线工况所产生的土体动应力最大值约为单线工况土体动应力最大值的2倍,动应力在隧道基底以下5m范围内衰减较快,且随深度呈指数型衰减。(4)单线工况基底土体压应变明显小于双线工况下的土体压应变,双线工况基底土体回弹应变大于单线工况下的回弹应变。(5)单线工况下基底超静孔隙水压力峰值约为2.5kPa,双线工况下的峰值约为5kPa,且基底超孔隙水压力最大值随距离的增加呈指数型减小。(6)隧道下卧层孔隙水压力与总应力的比值在0.6左右波动,下卧层粉砂层不会发生液化。
[Abstract]:The dynamic response of surrounding soil is caused by train operation, including acceleration, stress, strain, displacement, pore water pressure and so on.The engineering geological conditions of the tunnel crossing the river are complex, and the influence of the dynamic response of the soil caused by the subway operation on the engineering properties of the soil can not be ignored.At present, the research of soil dynamic response around single tunnel and double line subway tunnel has not been carried out systematically at home and abroad.The crossing section of Nanjing Metro Line 10 is the first single-hole double-line shield tunnel across the Yangtze River in China. This paper takes the section of this section near the north of the Yangtze River as an example.Using PLAXIS 2D, the dynamic response of soil around the tunnel caused by subway train operation is simulated by finite element method, and the liquefaction of sand under tunnel is analyzed.The following conclusions are obtained: 1) the dynamic response of soil is periodically changed by train dynamic action.Within the train passing time, 24 peaks appear, corresponding to 12 bogies and 24 wheelsets of a single train during wheel-rail contact.The acceleration decreases with the increase of the distance from the center of the tunnel.In the course of ground acceleration propagation,A maximum value appeared in the horizontal direction 10 m from the center of the tunnel.) the maximum value of dynamic stress below the base of the tunnel is 3.6 KPA under the single-line working condition, and the maximum value of the dynamic stress under the base of the double-line working condition is about 7.2 KPA, and the dynamic response of the soil produced by the double-line working condition is about 7.2 KPA.The maximum value of force is about 2 times that of the maximum dynamic stress of soil under single line working condition.The dynamic stress attenuation is faster in the range of 5m below the tunnel base, and it is exponentially attenuated with the depth of the tunnel, and the compressive strain of the foundation soil under the single line condition is obviously smaller than that of the soil under the double line working condition.The springback strain of soil in double line working condition is larger than that in single line condition.) the peak value of excess pore water pressure in single line condition is about 2.5 KPA, the peak value in double line condition is about 5 KPA, and the maximum value of excess pore water pressure in basement is with distance.The ratio of pore water pressure to total stress fluctuates around 0.6.There is no liquefaction of the silt layer in the underlying layer.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U452.11;U231.1

【引证文献】