川西地区水电站环境边坡危险源发育特征及分布规律

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

工程边坡"开口线"以上的自然边坡在风化、卸荷、地震动等的影响下,其表层任一局部失稳均会对其下工程和人员安全造成严重威胁。通过对川西6座重要水电站的环境边坡危险源的调查资料进行整理,研究不同种类危险源的发育特征及分布规律,结果表明:环境边坡岩体在顺倾、陡倾裂隙发育以及裂隙式和夹层式风化作用强烈等因素的控制下,形成危石、危石群和危岩体等危险源;危险源的体积集中在小型和中型规模范围内;危险源主要分布在环境边坡相对高程0~500m范围内,其中,危岩体的发育具有垂直分带性且集中分布在0~200m范围内;危险源所在环境边坡的坡度均大于25°,当坡度在35°~40°范围内时,危险源数量最多;对于相对高程0~500m、坡度35°~75°的环境边坡应进行重点勘察,根据危险源的种类和发育分布采取相应的防治措施。

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 thevolume 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 500 m 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 200 m. 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 500 m and gradient range of35°to 75° should be focused and the corresponding prevention measures are adopted on the basis of types and development distribution of hazardous sources.