新建并行工程对高铁轨道位移影响的概率分位研究

Probability quantitative study on influence of newly-built concurrent engineering on existing high-speed railway track displacement

目前,既有高速铁路用地范围内新建并行工程越来越普遍。在计算新建并行桥梁对既有高铁轨道位移的影响过程中,针对土层力学参数离散性大造成的计算结果可靠性难以评估的问题,建立土体-桥梁-轨道有限元模型,采用参数敏感性分析方法计算轨道位移变化对土层力学参数摄动的敏感性,提取敏感系数较大的参数,利用响应面法获得轨道变形与敏感的土层力学参量的多项式关系。根据土层参数的概率分布进行响应面函数计算,并评估计算结果的可靠度。研究结果表明:依托工程所处地区,轨道位移对含砾质黏土和粉质黏土的力学参数敏感性系数较大,其中内摩擦角对轨道位移的影响最为显著。对响应面函数进行评估,高铁轨道位移响应面预测值与有限元模型计算值的误差在1%之内,响应面函数可以代替有限元模型进行既有高铁轨道位移计算;以95%的置信水平计算土层参数变异时依托工程的桥墩位移,得到墩顶横向位移值为1.119 mm,竖向位移值为-0.725 mm,工程的可靠性较高。通过响应面拟合有限元计算结果,可以极大地提高计算效率,获得考虑土层参数离散性时既有高铁轨道位移计算结果的概率分位值,能为今后类似工程预测轨道位移提供一种可靠度分析方法。

Concurrent projects are becoming more and more common within the existing high-speed railway land. In order to solve the problem that the reliability of the calculation results was difficult to evaluate due to the large discreteness of soil mechanical parameters in the process of calculating the impact of new parallel bridges on the displacement of existing high-speed railway tracks, a soil-bridge-track finite element model was established. The sensitivity of the track displacement change to the perturbation of soil mechanical parameters was calculated by the parameter sensitivity analysis method. The parameters with larger sensitivity coefficients were extracted, and the track deformation and sensitivity were obtained by the response surface method. Then,according to the probability distribution of soil layer parameters, the response surface function calculation was carried out, and the reliability of the calculation results was evaluated. The results are drawn as follows.Depending on the area where the project is located, the sensitivity coefficient of track displacement to the mechanical parameters of gravel clay and silty clay is relatively large. The influence of internal friction angle on track displacement is the most significant. The response surface function is evaluated, and the error between the predicted value of the high-speed rail track displacement response surface and the value calculated by the finite element model is within 1%. The response surface function can replace the finite element model to calculate the displacement of the existing high-speed rail track, with a confidence level of 95%. When calculating the variation of soil layer parameters, relying on the pier displacement of the project, the lateral displacement value of the pier top is 1.119 mm, and the vertical displacement value is-0.725 mm, and the reliability of the project is high. By fitting the finite element calculation results with the response surface, the calculation efficiency can be greatly improved. The probability quantile value of the existing high-speed rail track displacement calculation results considering the discreteness of soil parameters can be obtained, which can provide a reliable method for predicting the track displacement for similar projects in the future.