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以上海地铁9号线三期工程为背景,对隧道周边1.5倍隧道外径范围内土体长期沉降进行现场监测。为分析上海软黏土在列车长期循环动荷载下的变形特征,通过引进考虑长期循环荷载作用效应的控制参数对现有动力循环加载弹塑性本构模型进行改进;采用改进的本构模型分析列车振动、工后固结2种工况下软黏土沉降发展规律。结果表明:通车850 d后,隧道拱底相对于地面的沉降实测值为4.7 mm,计算值为4.6 mm,其中由列车振动引起的沉降为3.1 mm,误差为2.0%,表明改进后的本构模型能够较好地模拟软黏土在列车振动荷载下的累积变形特征;振动荷载下隧道长期沉降符合指数型增长规律;在隧道埋深13.2 m情况下,列车振动引起的隧道拱底相对于地面的沉降经过约8 a趋于稳定,稳定后相对沉降量为4.2 mm。
Taking the third phase of Shanghai Metro Line 9 as the background, on-site monitoring of long-term subsidence of soil within 1.5 times of the tunnel’s outer diameter is carried out. In order to analyze the deformation characteristics of Shanghai soft clay under long-term cyclic loading of train, the existing elasto-plastic constitutive model of power cycle is improved by introducing control parameters that consider the long-term cyclic loading effect. The improved constitutive model is used to analyze the vibration of train , Post-construction consolidation of two conditions of soft clay settlement development. The results show that the measured settlement of the base of the tunnel with respect to the ground after the opening for 850 d is 4.7 mm and the calculated value is 4.6 mm. The settlement due to train vibration is 3.1 mm with an error of 2.0%, indicating that the improved structure The model can well simulate the cumulative deformation of soft clay under the train vibration load. The long-term settlement of the tunnel accords with exponential growth under the vibration load. Under the tunnel depth of 13.2 m, the tunnel arch bottom relative to the ground After about 8 a, the settlement stabilized, and the relative settlement after stabilization was 4.2 mm.