SUMMARY

Landslide assessment along the road 4D (Sa Pa - Lào Cai) based on studying the relationship between geological structure and topographic features

Chu Văn Ngợi, Nguyễn Thị Thu Hà

Landslide usually occurs along roads in mountainous area in the North Việt Nam and in specified road sections. Implementing the project QG-05-29, the author group has surveyed the geological structure along the road 4D from Sa Pa to Lào Cai city and analyzed the cause of landslide, especially assessed the role of geological structure in the road sections, where landslide usually occurs.

The research results have been noting that not only climatic and human factors, but also the relationship between geological structure and topographic features have an important role in landslide occurrence. The role of this relationship expressed in different conditions: 1) In case of similar topographic feature, the landslide occurs mainly depending on the relationship between geological structure and topographic feature. If the geological structure is characterized by blocks of hard rocks or foliated sedimentary rocks, whose layer dip direction is perpendicular to the direction of talus dip, then the geological structure is a factor of slope stabilization and rare occurrence of landslide; if the talus of the road comprises foliated sedimentary rocks, whose layer dip direction is parallel to the trend of talus dip, then the landslide easily occurs due to the geological structure; 2) When the geological structure is effaced to form a new structure which is characterized by fractured materials, then landslide occurs mainly by gravity factor. The research results are scientific basis for applying technique methods in mitigation of landslide hazard.

Ngày nhận bài: 24/1/2007

Người biên tập: Lê Đức An.