新建铁路隧道下穿既有铁路施工时引起地表沉降,这时对既有铁路运营安全的影响主要受控于轨道的前后高低差.采用ANSYS二维有限元方法,对新建铁路隧道下穿既有铁路工程建立数学模型,模拟计算不同最大等效应力、地质条件、隧道埋深、隧道结构形式等96种工况下的地表沉降量.并利用Peck公式回归分析得到96种工况下的沉降槽宽度系数.对模拟结果和回归结果进行数据分析,推导出沉降槽宽度系数与隧道埋深的关系式,以及地表最大沉降最与地层弹性模量、最大等效应力、隧道埋深的关系式.在此基础上,根据地表沉降曲线的正态分布规律、沉降槽宽度系数的数学意义和轨道的前后高低差管理值,推导得到新建铁路隧道下穿各等级既有铁路时的地表沉降控制标准.%Ground surface settlement occurs when the new-built railway tunnel under-passing the existing railway is constructed. At this time, the influence on the operation safety of the existing railway is mainly controlled by track irregularities. ANSYS 2-D FEM was adopted to establish the mathematical model for the engineering of new-built railway tunnel under-passing the existing railway. By which ground surface settlement was simulated under 96 conditions of different maximum equivalent stress, geological condition, buried depth and tunnel structure, etc. Regression analysis was carried out by Peck formula to obtain the width coefficient of settlement trough under 96 conditions. Based on the simulation and regression results, the relation between the width coefficient of settlement trough and the buried depth was derived. The relation was also put forward between the maximum ground settlement and the elastic modulus of strata, maximum equivalent stress and the buried depth. On this basis, according to the normal distribution law of ground settlement curves, the mathematical meaning of the width coefficient for settlement trough and the management value of track irregularities, the control standards for the ground settlement of the new-built railway tunnel under-passing the existing railway of different grades were derived.
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