Risk assessment of rockfall hazards on highways

With the rapid development of the west region of China, a great number of highways are being or to be built in the western mountainous region. Rockfalls constitute a major hazard in numerous adjacent rock cuts or steep natural rock slopes along these highways. In this paper, the connotations, extensions and characteristics of rockfall are discussed and the triggering mechanism is analysed. The widely accepted relative rockfall rating systems are introduced. Based on the Italian modified rockfall hazard rating system, the weights of all categories including five rockfall hazard factors and four vehicle vulnerability factors are introduced to enhance the major categories and weaken the minor categories. In addition, according to the different influence degrees of risk environment and road forms, the modified coefficients are introduced to improve the initial results. Finally, an example with this method to assess a section along Shuifu-Maliuwan highwayin Yunnan Province was developed. Through rockfall hazard assessment, in this section, we find four intervals which are very hazardous. Some further analysis and investigation on geotechnical stability was recommended. And some necessary measures should be taken to reduce rockfall hazards in these four intervals.