浙江仙居拱坝拱座稳定不利结构面的处理

浙江省仙居水电站拱坝左岸坝头山体较雄厚,且软弱夹层出露的高程较高,故采用扩大基础的推力墩结构。右岸由于软弱夹层与陡倾角节理形成底裂面和侧裂面的组合,对坝基的抗滑稳定不利,采用开挖置换混凝土回填基础的处理方案,同时对软弱夹层采取混凝土洞塞处理。通过对影响拱座稳定的各滑裂面和临空面的分析研究,对于不同的不利结构面采取了相应的工程措施,既节省了开挖方量,又确保了拱座稳定。

Treatment of unfavorable structural plane to stability for abutments of Xianju Arch Dam

For the arch dam of Xianju Hydropower Station in Zhejiang Province,the mountain body of the abutment on the left bank is quite thick with the emergence of weak intercalated layers at higher elevation;therefore,the thrust pier with enlarged base is adopted.Furthermore,the combination of the bottom cracking surface and the side cracking surface created by both the weak intercalated layers and the steeply inclined joints on the right bank is unfavorable to the stability of the dam foundation against sliding.Under this condition,the treatment method of replacing the excavated portions with backfill concrete for the foundation is adopted together with concrete plugging in the weak intercalated layers.Through the analysis on the effects from all the sliding surfaces and the free surfaces on the stability of the abutments,relevant engineering measures are applied to the various unfavourable structural surfaces;by which not only the excavation amount is saved,but the stabilities of both the abutments are also guaranteed.