瀑布沟大坝为砾石土心墙堆石坝,如果上游库首右岸拉裂变形体边坡失稳,滑体涌浪是土石坝的重大安全隐患,可能堵塞引水和泄水建筑物进口,影响其正常运用。综合考虑各因素后,库首右岸拉裂变形体按B类1级边坡设计。边坡分为松动带、拉裂变形带和正常岩体3个带,表层以小规模塌滑为主,后退式地逐步发展;深部变形以卸荷拉裂为主。在地质条件详细勘探的基础上,分析坡体拉裂变形体结构和破坏模式,并进行边坡稳定性分区和计算分析。根据坡体变形和破坏特点,结合瀑布沟工程总体施工进度安排,采取不开挖、强支护(深层锚索与浅层支护相结合)、分区和分期支护、整体控制的加固措施,实时监测成果并进行动态设计和调整。根据一期、二期初步治理后的监测分析表明变形已趋缓、无异常变形的迹象、未出现滑移带,但仍需要重视边坡监测成果的反馈分析,为后期支护设计优化提供依据,以确保边坡的长久安全稳定。瀑布沟库首右岸拉裂变形体位治理的设计思路、加固措施、计算方法、监测手段及评价过程,可为其它类似变形体边坡的治理提供借鉴。

Pubugou dam is a gravel-soil-core rock-fill dam, if the upstream slope fails, the surge wave would pose great danger to the dam and block the intakes. Given those factors, the deformation and fracture mass is designed as a B1 slope. The slope is divided into 3 zones surface loose zone with small scale slip from the surface to inner layer, off-load deformation zone with relaxed-tension crack and sound rock zone. After detailed exploration, we analysed the slope structure, failure pattern and stability zoning according to the geological conditions. In line with the deformation and failure features and the construction progress of pubugou hydropower station, we took reinforcement measures which contain no excavation, strong support (deep anchorage and surface support), support at different periods and areas, and integral control. Those measures are dynamically adjusted and designed with real time monitoring results. Analysis on the monitoring result after the first stage and preliminary treatment of second stage shows that the deformation trend is becoming slower and no abnormal deformation or sliding layer occurs. In order to provide basis for optimization and make sure the slope is stable in the future, the analysis on the monitoring result is highlighted. This paper provides design idea, reinforcement measures, calculation method, monitoring apporoaches and evaluation process for other similar conditions.