Study Of Stability Of Embankment Upon The Slope In The Permafrost Area At Anduo Section Of Qinghai-Tibet Railway

There is a potential threat to long-period operation in the sector of embankment upon the slope, so it is important for instructing correct design and construction to evaluate the inclined embankment of recent or future time. Stability assessment of railway roadbed slope in permafrost area is difficult from others, because the location of interface between frosting and thawing is an allimportant factor to the stability of the embankment. Through monitoring the features of temperature and displacement of embankment, and forecasting the trend of temperature and displacement during 50 years in the paper, the recent and future appraisal models are built which is considerated the influence factors such as longitudinal cracks, geogrids, rainfall infiltration and earthquake, etc. After analyzing, the conclusions are as followed:1. Field is ground temperature field of embankment is re-distributed due to building railway in permafrost area. Since the asymmetry of aspect and geometric in the railway, the field of temperature of embankment is presented dissymmetry at ubac and solar slope, which causes the roadbed asymmetric settlement.2. The roadbed horizontal displacement mainly occurs in the soil above the roadbed artificial permafrost table, thus, author deems the freezing-thawing interface is the latent sliding surface. The interface is not the normal rock bounding surface, while the crossing surface of thawed layer and frozen layer. According to the location of the interface and feature of the ground temperature in active layer, embankment in permafrost area is divided into four times, that are server cold time in winter (Jan. to Feb.), thawing time in spring or summer (Mar. to Aug.), the time of deepest thawed depth in summer (Sep. to Oct.) and freezing time (Nov. to Dev.).3 The stability coefficient in the time of deepest thawed depth is lowest through evaluating the embankment in different times.4. The evaluation result indicates the lowest stability coefficient of roadbed slope do not occur the time which the rain just stops, while in two days later.5. The result indicates that permafrost soils in roadbed begin to gradually degenerate after 20years from the numerical simulation. The plastic yield zone of permafrost embankment is close to lowest coefficient surface in limited balance method. Though analyzing the future assessment model, the stability coefficient reaches the lowest in the tenth year.