宝兰客专路堤段地面振动特性试验研究与数值分析

Experimental study and numerical analysis on ground vibration characteristics of subgrades section of Baoji-Lanzhou high-speed railway

基于高速列车动荷载激励引起的无砟轨道-路基-黄土地基体系的地面振动问题,对宝兰客专DK993+110处路堤区段地面振动进行试验研究和数值分析。对试验数据从时域和频域2个方面进行分析,研究不同车型的动荷载引起地面垂向振动加速度在黄土地基中的衰减规律,研究结果表明;在距离线路中心线10～24m衰减较快,随着距离增大,距离线路中心线24～42m衰减速度趋于平缓,且在30～42m处各型车引起地面振动均出现了振动反弹增大现象。建立车辆-轨道-地基系统模型,研究列车动荷载作用下的地面响应,发现与实测结果吻合良好,验证模型的合理性与计算的正确性,依据不同场地速度结构,通过改变地基介质模量比和覆盖层厚度的方式,分析地基介质模量比和覆盖层厚度对振动反弹增大的影响。分析车速对地面振动的影响,发现地面振动随车速增大呈增大趋势,且不同车速列车引起振动反弹区域也有一定差异。按《城市区域环境振动标准》评价该处地面振动Z振级,回归分析得出各型车引起Z振级符合对数衰减规律,但在振动反弹区30～42m处拟合效果较差,表明拟合公式适用范围应当限定在10～30 m之间。

Based on the ground vibration problem of ballastless track-subgrade-loess caused by high-speed train dynamic load, the experimental study and numerical analysis in subgrade of Baoji-Lanzhou High-speed Railway were carried out. Combined with experimental data, this paper analyzes the transverse attenuation law of soil vibration acceleration caused by dynamic load of different train, The results show that the attenuation is faster at 10~24 m from the central line of the line. With the increase of the distance, the attenuation speed of 24~42 m from the central line of the line tends to be flat, and the vibration rebound and increase of the ground vibration were caused by each type of vehicle at the distance of 30~42 m are observed. The model of vehicle-track-foundation system was established, and the ground response under the action of train dynamic load was studied. It is found that the model is in good agreement with the measured results, which verifies the rationality of the model and the correctness of the calculation. By changing the modulus ratio of the foundation medium and the thickness of the overburden, the effects of the ratio of the modulus ratio of the foundation medium and the thickness of the overburden on the increase of the vibration rebound are analyzed. The influence of vehicle speed on ground vibration was analyzed. It is found that the ground vibration increases with the increase of speed, and the vibration rebound region caused by different speed trains is different to some extent. According to the Standard of Environmental Vibration in Urban area, the Z vibration level of ground vibration is evaluated. The regression analysis shows that the Z vibration level caused by each type of vehicle conforms to the logarithmic attenuation law, but the fitting effect is poor at 30~42 m in the vibration rebound area. It shows that the applicable range of fitting formula should be limited between 10~30 m.