Rock mass types and their bearings on the geologic hazards in the Luding region,Sichuan

The initiation,development and occurrence of geological hazards are attributed,without exception,to different types of activity of rock masses.The exposed strata in the Luding region,Sichuan may be classified,on the basis of physical properties,hardness and lithology,into three engineering geological rock associations,including friable rocks,semihard-hard rocks and hard rocks.The friable rocks are generally easy to bring about the geological hazards such as landslides,debris flows and unstable slopes.The semihard-hard rocks may be related to the geological hazards such as landslides,rock avalanches and unstable slopes.As the hard rocks,there is no possibility for the acidic rocks to result in the geological hazards;only the intermediately basic to ultrabasic rocks may be responsible for the generation of rock avalanches.