云口水电站重要工程地质问题及对策

Key Engineering Geological Problems and Countermeasures of Yunkou Hydropower Station

云口水电站左岸河间地块的岩溶渗漏问题和左坝肩边坡稳定问题是本工程最重要的地质问题,前者直接关系到成库条件及工程的成败。通过岩溶水文地质调查、勘探试验工作,查明库区的岩溶发育特征,为水库的蓄水方案提供地质依据。根据岩溶水文地质在平面上分区、垂向上分层的特点,对库区岩溶渗漏问题进行分析计算,并确定大坝防渗帷幕方案。坝址边坡陡峭,左坝肩为顺向斜向坡,岩层产状及裂隙发育特征对边坡稳定极为不利,开挖边坡的稳定性较差,施工难度也相当大。针对不利的地质条件,左坝肩施工开挖采取窑洞式开挖方式,并控制梯段开挖规模,尽量避免扰动岩体,同时对裂隙岩体采取锚索、系统锚杆、挂钢筋网喷护的组合支护措施。实践证明,支护工作取得了良好的效果。

Karst leakage in the interstream area on the left bank and slope stabilization on the left abutment ol Yunkou hydropower station are the most salient geological problems, and the former is ol vital important to the forming condition lor the reservoir and the success or failure ol whole project. Through the investigation and survey on the karst hydrogeolo-gy ,the features ol karst development are detected,which provides geological evidences for selecting the reservoir storage scheme. According to the characteristics ol plane divisional and vertical stratification for the karst hydrogeology, the res-ervoir leakage problems are analyzed and calculated,and then the anti-seepage curtain lor the dam is determined. The ge-ological claim is that the steep slope at dam sites, the left abutment with consequent slope structure, and the characteris-tics ol the attitude ol rock lormation and lracture development place the slope stability at a signilicant disadvantage. These results go against the excavation slope and increase the difficulty for practical construction. Aiming at disadvanta-geous geologic conditions,the excavation ol the left abutment is conducted by the method ol cave-dwelling and controlling the bench dimension to reduce disturbance on rock mass. At the same time, the combination ol anchor lines, system bolts and steel mess shotcrete is applied lor the fractured rock mass as support measures,which proved to be effective.