八一水库溃坝原因分析

Analysis of dam break of Bayi Reservoir

八一水库是中型水库,由于新建泄洪涵洞与原土坝之间新填土体坝顶裂缝渗透破坏,于2004年1月溃决。破坏原因是新建泄洪涵洞处原土坝开挖断面狭窄,左侧边坡偏陡,涵洞外壁截渗环过密,环径大,新填坝体填筑速度快,上部质量低,完工后立即蓄水,新填土坝左侧不均匀沉降过大,坝顶出现横向裂缝,当库水位接近正常蓄水位时,渗流从下游坝坡较高处逸出,出口无反滤保护,坝顶裂缝渗流冲刷,导致溃坝。

The dam of the Bayi Reservoir, which is a medium-size project, breached in January 2004 due to seepage failure at the junction between the newly filled earth dam section and the old embankment section. The junction was close to the embedded sluice conduit.The space for excavation was too narrow and the slope on the left bank was very steep. The cutoff collars of the conduit were too close to each other and too large in diameter. The filling placement was too fast and compaction quality was poor, thus created weak areas in the section. The reservoir impounding started immediately after completion of the new earth dam section. Excessive differential settlement at the left portion of the new dam section was resulted and some transverse cracks appeared. When the reservoir water level rose close to the normal water level, a seepage outlet emerged at the downstream dam slope at a high point where no filter protection was provided. The dam finally collapsed as a result of all the processes above mentioned.