斋堂水库“23·7”洪水后上游坝坡裂缝成因分析

Causes of upstream dam slope cracks in the Zhaitang Reservoir after the“23·7”flood

2023年7月,北京发生新中国成立以来最大的暴雨,此次洪水致使大部分水库工程坝体结构受到影响。本文以“23·7”洪水过后斋堂水库上游坝坡裂缝为研究对象,在现场调查测绘的基础上,结合高密度地震映像法、裂缝内部管窥摄影以及坝顶高程及坝坡高程复核,研究了上游坝坡裂缝产生原因。结果表明,“23·7”洪水期间水库水位降幅大,水位下降快,造成坝体内渗水不能及时外排,增大了渗水对坝坡向下的渗透压力,砌石护坡及下部垫层料向下滑动,是导致裂缝产生的主要原因;由于新、老坝体料密实程度不同,产生的不均匀沉降变形是裂缝产生的另一原因;护坡石下部未发现裂缝,大坝上、下游面均较为平整,坝顶高程及坡比与设计参数基本一致,“23·7”洪水后上游坝坡出现的裂缝未对大坝坝体安全造成影响。

In July 2023,Beijing experienced the heaviest rainfall since the founding of the People’s Republic of China,which resulted in the impact on the structural integrity of many reservoir dams.This paper focuses on the cracks that appeared on the upstream dam slope of the Zhaitang Reservoir following the“23·7”flood.Based on field investigations and surveys,combined with methods such as high-density seismic imaging,internal crack borescope photography,and verification of dam crest and slope elevations,the causes of the upstream dam slope cracks were studied.The results show that during the“23·7”flood,the reservoir water level dropped significantly and rapidly,preventing seepage from being discharged from the dam in time,which increased the downward seepage pressure on the dam slope.The sliding of the masonry slope protection and the underlying base materials was the main cause of the cracks.Additionally,uneven settlement and deformation due to the difference in the compactness of the materials between the new and old dam bodies was another cause of the cracks.No cracks were found under the slope protection stones,and the upstream and downstream faces of the dam were relatively flat.The dam crest elevation and slope ratio were basically consistent with the design parameters.The cracks on the upstream dam slope after the“23·7”flood did not affect the safety of the dam structure.