大藤峡水利枢纽主坝为混凝土重力坝。根据前期勘察及施工期开挖揭露,泄水闸坝段坝基岩体发育多条层间软弱夹层,性状较差、连续性好,产状缓倾下游偏左岸,可构成坝基深层滑移边界。针对上述工程地质问题,通过分析软弱夹层分布及性状,确定结构面力学参数;进行软弱夹层与断层、节理空间组合,确定滑移模式;以刚体极限平衡法进行滑面深度的敏感性分析,并进行坝基深层抗滑稳定性计算,评价坝基深层抗滑稳定性;对不满足规范要求的坝段,亦在计算成果基础上,提出了针对性处理措施,取得理想效果。研究成果可为大型水利水电工程重力坝深层抗滑稳定性研究提供启示和借鉴。

The main dam of the Datengxia hydro-project is a concrete gravity dam. According to survey and excavations, many soft and weak interlayers develop in the dam foundation rockmass of the release sluice segment. The soft and weak interlayers are characterized by poor performance, good continuity, gentle dip towards the downstream left bank, forming a deep sliding boundary of the dam foundation. In this study, the mechanical parameters of structural plane are determined by analyzing the distribution and properties of these soft interlayers, and the slid patterns are determined by the spatial combination of soft interlayers and faults. Moreover, the sensibility of sliding surface to depth is analyzed using rigid limit equilibrium method, and the deep anti-sliding stability of dam foundation is calculated and evaluated. According to the calculation results, treatment measures are put forward for dam segment which do not meet requirements. This research provides a typical case for the study of deep anti-sliding stability of gravity dams in large hydro-projects, and also provides enlightenment and reference for similar projects around the world.