DEVELOPMENT CHARACTERISTICS AND DISTRIBUTION LAWS OF HAZARDOUS SOURCES ON SLOPES SURROUNDING HYDROPOWER STATIONS IN WESTERN SICHUAN

Under the influence of weathering, unloading and earthquake, any local instability of natural slope surface above the"opening line" of engineering slope can pose a serious threat to engineering and personnel safety. According to the survey data of hazardous sources of slopes surrounding six important hydropower stations in Western Sichuan, China, the development characteristics and distribution laws of different types of hazardous sources are studied. The results show that under the control of factors of fracture development of down dip and steep dip and strong weathering of fracture type and sandwich type, the rock masses of surrounding slope generate the hazardous sources, such as collapse rock, collapse rock group and dangerous rock mass. It can be found that the volume of hazardous source concentrates upon the range of small and medium size. The hazardous sources are mainly distributed on the surrounding slope with the relative elevation range of 0 to 500m and the development characteristic of dangerous rock mass is vertical zoning, which are intensively distributed on the surrounding slope with the relative elevation scope of 0 to 200m. It also indicates that the surrounding slope gradient of hazardous sources distribution is more than 25°.The quantity of hazardous sources is most when the gradient is ranged from 35°to 40°. The investigation of surrounding slope with the relative elevation scope of 0 to 500m and gradient range of 35°to 75°should be focused and the corresponding prevention measures are adopted on the basis of types and development distribution of hazardous sources.