The magnitudes of impact force on civil engineering structures depend significantly on the total rockfall volumes and the evolution of rockfall processes.

The magnitudes of impact force on civil engineering structures depend significantly on the total rockfall volumes and the evo- lution of rockfall processes.

Obviously,risk analysis of encountering rockfalls along these traffic routes is of extreme importance for zoning of rockfall hazards and optimum scheme of mitigation costs.

Engineering geological investigation on mountainous hazards along Basu-Linzhi section of the south line of Sichuan-Tibet highway,is conducted,which indicates that rockfall hazard is extremely serious and should be treated as a special kind of hazard with great attentions.

On the basis of analysis on rockfall hazards at home and abroad,the studies on rockfall are classified as four aspects,risk analysis,rockfall trajectory,rockfall impact force a.

With the ceaseless extent and intensity of human activities, the problems of rockfalls and rockfall hazards become more and more prominent, especially in the mountainous regions.

The problems of debris flow disasters will be more important in the town planning and construction.

In accordance with special hills terrain and debris flow disasters in Miyun county,access to relevant literature and research results,select a typical debris flow groove,investigate the type of mud-rock flow,the formation of conditions,treatment status and human activities and so on.