城际铁路地下段运营振动对上部埋地燃气管道的影响

Impact of the vibrations induced by the subsurface coverage of the intercity railway on the buried-below gas pipeline

以某城际铁路下穿埋地燃气管道工程为例,应用车辆-轨道耦合动力学理论建立了车辆-轨道垂向耦合动力学模型,计算了250 km/h行车速度下的钢轨扣件支点反力;利用ANSYS建立了包括轨道、隧道结构、土体和燃气管道的三维有限元模型,以钢轨扣件反力为输入荷载,分析了列车运营条件下燃气管道的振动响应特性,并分析了会车对燃气管道振动响应特性的影响。结果表明,当列车单向运营速度为250 km/h时,燃气管道的最大振动加速度为1.175×10^(-3)m/s^2。如果在管道下方会车,列车运行振动对埋地燃气管道的影响范围显著增大,振动位移幅值和加速度幅值增幅分别为85.2%和75.8%,最大位移为2.21×10-5m,最大振动加速度为2.12×10^(-3)m/s^2。根据预测计算结果判断,本工程列车单向运营引起的埋地燃气管道的振动烈度小于I度,会车时振动烈度略大于I度。

The paper is inclined to make a study on the impact of the vibration induced by the intercity railway＇s subsurface coverage on the beneath-buried gas pipeline. As a matter of fact,vibrations induced by the moving trains may cause damage to the buried gas pipelines,which is of a major concern in recent years not only to the gas pipeline builders,but also to the whole urban communities. In order to investigate such a kind of impact of vibration with the CRTS I bi-block endless track on the buried gas pipeline,the paper has established a vehicle-track coupled dynamical model in the vertical direction based on the theory of vehicle-track coupled dynamics,with the rail-supporting force being calculated at a speed of 250 km/h. At the same time,we have also set up a 3D dynamic finite element model in this connection via the ANSYS so as to disclose such impact of the vibration while taking into account the conditions of one way traffic and the trains by-way passing at a speed of 250 km/h. In addition,we have also modeled the soil and the monolithic track bed with eight node brick solid element. Furthermore,we have modeled the tunnel line and the gas pipeline with four-node shell element and pipe element in numerical simulated manner,too. In this way,we have adopted the non-reflected boundary in the 3-D finite element model to ignore the boundary effect. The numerical simulation results have shown that the maximum accelerated displacement of the pipeline can be 1. 175 × 10-3m/s2 under the condition of one way traffic. The impact range induced by the meeting trains is likely to be remarkably greater. The peak displacement and the peak acceleration of the said pipeline in case of by-way passing trains at a speed of 250 km/h have been found equal to 2. 21 × 10- 5m and 2. 12 × 10-3m/s2. Technically speaking,the displacement tends to be bigger than those of the one way traffic by 85. 2% and75. 8%,respectively. Therefore,if measured on the railroad vibration intensity scale,the vibration intensity of the buried gas pipeline can be lower than I magnitude number under the condition of one way traffic,and slightly higher than I magmitude in case of crossing of two opposite trains. Therefore,the results of our monitoring and measurement indicate that the impact of the vibration induced by the operating intercity trains on the buried gas pipeline proves to be insignificant.