Assessment of low-frequency plateau debris flow risk along expressway considering the threatened highway facility constructures

The transition area between the Tibet plateau and the Sichuan basin has a big elevation difference and sensitive environment, the new build expressway from Wenchuan to Marcon suffering debris flow before it formally running. After investigation and data analysis, the reason caused debris flow is heavy rainfall cause some landslide in the both banks of gully, investigation also found different structure of the expressway cause different result. In order to make effective mitigation for expressway, a susceptibility analysis of struck area was made, the geology environment, rainfall intensity map from TRMM and GPM data and NDVI and the loose material evaluation from remote sensing data were used in gully scale, the susceptibility model is AHP method and compared with the synthetic model proposed by Liu xilin(2002). The expressway suffering debris flow because the exposure and the facility structures, with this idea and the concept of risk given by the UNESCO, the disaster resistance were classed by 5 kind of structures, the final result show the right bank is much higher risk and some corresponding mitigation works were proposed.