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.