2019 Volume 7 Issue 2 Pages 154-158
During the construction of the South-to-north water transfer middle line and Jilin-Hunchun high-speed railway line, a lot of excavations in swelling rock and soil were performed to achieve acceptable grades, eventually forming extensive swelling rock and soil slopes. Many of them slid after water storage and rainfall events. One interesting observation is that most of the landslides are south-facing. In this paper, the causes of this direction variation were thoroughly examined on the basis of the geological characteristics of project sites. It is concluded that the water storage and rainfall event are the direct external trigger of landslides while the intensive soil-atmosphere interaction is the main reason for the landslides in south-facing direction. Because of the influence of slope orientation, the solar radiation, temperature and humidity on south-facing and north-facing slopes are materially different. The unloading fissures caused by excavation unloading and the shrinkage fissures act as a main channel for the exchange of moisture and energy between soil and atmosphere. Owing to the intensive solar radiation and high temperature on the south-facing slopes, they are subjected to dramatic wetting-drying and freezing-thawing cycles, which can lead to a remarkable decrease in the strength of swelling rocks and soils. They are therefore more possible to slide.
