HIGHWAY GEOLOGICAL HAZARDS OCCURRING ON MULTI-STAGE ACCUMULATIONS OF DEBRIS FLOWS——A CASE STUDY OF THE BIETUO SECTION OF THE WEST APPROACH OF THE ERLANG MOUNTAIN TUNNEL,SICHUAN-TIBET HIGHWAY

The main communication lines in western China are mostly located in mountainous areas, where in history there exist multi-stage accumulations of debris flows which have preferable stability and structural strength in the natural state.How to make rational use of this kind of accumulation and avoid occurrence of engineering geological hazards in highway construction has practical significance.In this paper the multi-stage accumulation of debris flows in the Bietuo section of the west approach of the Erlang Mountain tunnel along the Sichuan-Tibet Highway is selected to study its development, distribution and evolutionary trend, and then the highway engineering geological hazards such as landslides, uneven settlement of the roadbed and deformation of bridge foundation occurring in this section are analyzed and evaluated.At last the authors give some important advices for highway construction on multi-stage accumulations of debris flows.