Derong County is located in Ganzi Tibetan Autonomous Prefecture in southern part of Sichuan Province, in the upper of the Jinsha River, where there is a subtropical plateau monsoon climate, abundant sunshine, and large amount of evaporation, so it is a typical dry-hot valleys region. Derong County is the area of more ups and downs in the terrain, deep valleys, steep mountains, complex geological conditions, intense tectonic activity, various climate types, and has obvious vertical zone effect by temperature, serious physical weathering of rock, and landslide, debris flow, collapse and other geohazards are easily induced under the influence of rainfall and human engineering activities. These geohazards have brought serious harm to the people's lives and property, and have a great impact on the socio-economic development. Through the analysis of geohazards in the study area to investigate its distribution and development trends, this paper provide a basis for geohazard prevention and economic development.

Failure analysis was carried out to find out the causes of burst on water-cooled wall tubes elbow for circulating fluidized bed (CFB) boiler.Through macro-observations, chemical composition analysis, macro structure observations，grain size measurements and water quality examinations, it can conclude that the high pH value of boiler water at the fire-facing side of weld dense phase zone will lead to alkali concentration that will cause alkali corrosion. The existence of residual stress in elbow under strong alkaline environment will cause alkali stress corrosion. Research results show that the tube failure is caused by both alkali corrosion and alkali stress corrosion. Strengthen water quality monitoring and elimination of stress can effectively prevent the alkali corrosion and alkali stress corrosion.