复杂大气环境作用下高铁路基水分迁移响应

Moisture migration in a high-speed railway embankment under complex atmospheric environment

高铁路基作为列车和轨道结构支承体,直接暴露在复杂大气环境中,受降雨、蒸发等长期循环作用,含水率、基质吸力和剪切强度响应复杂,影响路基长期稳定性。建立了考虑大气作用的水-热耦合高铁路基水分迁移计算模型,通过法国鲁昂路基现场试验案例分析验证了计算模型。利用北京、上海两地2013年实测气象数据,对高铁路基含水率响应进行计算,研究了不同气候和填料类型对体积含水率变化的影响。结果表明:填料和气候类型对路基含水率响应影响显著。大气对砂土路基影响深度较浅(深度<3.0 m),浅层(深度≤1.0 m)受大气环境影响非常显著,含水率波动范围较大;粉土和黏土路基的含水率受大气影响的深度较深,超过3 m深度,但含水率波动范围较小。北京气候条件下路基含水率季节性差异较大,上海气候条件下路基含水率随单次降雨波动更明显。

High-speed railway embankment as the supporting body of the train and track is directly exposed to the complex climate conditions such as the rainfall, evaporation and other environmental events. These conditions change the water content, suction and shear strength of the filling soil, and further affect the stability of the embankment. A moisture migration model of the high-speed railway embankment with considering environmental effects is proposed. The model is verified by comparing with the measured data of a highway embankment in Rouen, France. Based on the meteorological data of Beijing and Shanghai in 2013, the volumetric water content（VWC） response of the high-speed railway embankment is calculated to investigate effects of climate conditions and soil types. The result shows that, the soil type and climate condition significantly affect the moisture variation of high-speed railway embankment. The influential depth of atmospheric environment on the VWC of sandy embankment is small, but the shallow embankment is affected by the atmospheric environment significantly with a large amplitude of VWC fluctuation. The influential depths of atmospheric environment on the VWC of silty and clayey embankment are relatively deep, but the amplitude of VWC fluctuation is small at every depth. The VWC of embankment under weather condition of Beijing has a huge seasonal variation and the VWC of embankment under weather condition of Shanghai fluctuates significantly with each rainfall.