青藏铁路冻土区遮挡式路基结构安全可靠性预测分析

冻土区路基的安全可靠性取决于路基地温场特征和路基面抗自然侵蚀特征。在路基基床上部修筑遮阳棚和在边坡上修筑遮阳板既可阻挡太阳对路基面和路基边坡的直接辐射,改变路基地温场形态,降低土层温度,又可防止降水渗入路基或降雪覆盖路面。这对防止冻土退化,提高冻土区铁路路基安全可靠性是一种非常有效而又简单易行的工程措施。本文以青藏铁路冻土区遮挡式路基结构路基表面温度数据和该地段气象资料为基础,运用带有相变的一维热传导方程模拟分析了青藏铁路长期运营过程中遮挡式路基结构对冻土区路基人为上限的抬升效果及对路基稳定性的影响,认为遮挡式路基结构是一种安全可靠的冻土区路基工程结构形式,同时也是未来铁路运营过程整治路基病害的一种有效工程措施。

PREDICTIVE ANALYSIS ON SAFETY RELIABILITY OF UMBRELLAED EMBANKMENTS FOR QINGHAI-TIBET RAILWAY IN PERMAFROST AREA

The safety reliability of railway embankments in permafrost area largely depends on the thermal field and the erosion resistant of the embankment. The umbrellas such as awning above the embankment or shading plate on the embankment slope not only block the solar radiation directly onto the embankment and slope, but also prevent the embankment and slope from rain infiltration and snow accumulation, which can change the ground temperature and reduce the variation of the ground temperature and moisture contents. Such umbrella method can be effective and operational to prevent the embankment from permafrost degradation. In order to determine to the upper limit lift and the roadbed stability, this special embankment is modelled by applying one-dimension heat conduction equation in the paper. The modeling includes phase change, combines with temperature information and meteorologic report of the shading embankment. The field observation and modeled result have shown that the umbrella method is reliable and safe. This umbrella protection approach would be an effective measure to prevent the railway disease during operation.