大型导流隧洞群下闸封堵风险分析及对策——以乌东德水电站为例

Risk analysis and countermeasures for gate closing and plugging of large scale diversion tunnel groups:case of Wudongde Hydropower Station

高拱坝通常会在坝身较低高程处设置导流底孔,以降低下闸安全风险,同时满足中后期导流和初期蓄水时下游生态供水需求。但由于高拱坝坝体底部空间有限,坝身设置导流底孔易导致坝体结构复杂、占用大坝直线工期、投资大、初期蓄水泄放生态流量小甚至下游脱水断流等问题。以中国首个坝身不设导流底孔的高拱坝——乌东德大坝为例,开展了复杂地质条件下超大型导流隧洞群下闸封堵风险分析及对策研究,分别从下闸遇超标流量、闸门失稳、下闸不到位、地下洞室失稳、异常渗漏、洞内气爆、工期延迟等安全风险方面展开具体分析,并研究制定相应对策,保障了乌东德水电站导流隧洞下闸封堵安全。相关安全风险应对措施和管理经验可为类似工程提供借鉴参考。

The bottom diversion outlets are usually set for high arch dams at the bottom of the dam body to reduce the safety risk of gate closing,and at the same time to meet the needs of the later diversion and the downstream ecological water supply in initial water storage.However,due to the limited space at the bottom of the high arch dam body,setting the bottom diversion holes in the dam body can easily lead to complex structure stress of the dam body,occupation of the straight time of dam construction,large investment,small ecological flow during initial water storage period and even downstream dehydration and disconnection.Taking the Wudongde dam,the first high arch dam without bottom diversion outlet in China as an example,the risk analysis and countermeasures for gate closing under complex geological conditions were carried out.The specific analysis was carried out from the safety risks of gate facing super flood,gate instability,inadequate gate closing,underground cavern instability,abnormal leakage,gas explosion in the tunnel and time delay.And then the corresponding countermeasures were studied and formulated to ensure the safety of gate closing.Relevant safety risk response measures and management experience can provide reference for similar projects.