Characteristics and potential engineering perniciousness of the debris flow group in one station of the Sichuan-Tibet Railway

Abstract

One station of the Sichuan-Tibet Railway is located in the Dongcuoqu valley in southeast Tibet of China, and also lies in the debris-flow-prone area. Based on field investigations and remote sensing interpretation, we revealed the predisposing conditions and characteristics of the debris flow group, which have significant influence on the station safety. The results suggest that this region is characterized by ten rainstorm-induced debris flows and two glacier lake outburst-induced debris flows. Geomorphology, water sources and material sources exert dramatical controls on the characteristic of debris flows. Complex geological and environment background provides adequate material sources and potential energy conditions prone to the formation of catastrophic debris flows. The integrity coefficient of the debris flow gullies ranges between 0.15 and 0.55, with the morphology of long strip and oak leaf shape. The longitudinal slope of the main channel is relatively large, which is conducive to the water catchment and occurrence of debris flow. The slope of the channel bank slope in the debris flow basin is mostly 20°−40°, which provides appropriate supply to the material sources. We also calculated the kinetic parameters of 12 debris flows, and analyzed their dynamic characteristics and development tendency. The deposition fans of the debris flow group are ubiquitous without mitigation measures. Large-scale debris flows are prone to occur under the extreme rainstorms. Finally, we evaluated the potential engineering perniciousness of debris flow on railway in single debris flow-occurring circumstance and in debris flow-occurring in the both banks of the Dongcuoqu circumstance. It is suggested that drainage channels should be built for the railway at the deposition fan of gully for return flow, and safety measures should be taken to prevent boulders impact on the proposed bridge piers. Results in this study are expected to guide the design of the debris flow mitigation project in Sichuan-Tibet Railway, and also provide scientific basis for the reasonable selection of the vital traffic line in the mountainous areas.

Keywords

• sichuan-tibet railway
• debris flow group
• hazard-inducing environment
• glacier lake outburst
• dongcuoqu valley