Seismic damage analysis and reinforcement measure research for earth dams after a strong earthquake

Abstract

At present, there are more than 98,000 reservoirs and dams in China. Most of these projects are earth dams. As unexpected disasters and events occur frequently, emergency response problems facing reservoirs and dams are increasingly prominent. Especially during a strong earthquake, the dangerous problems of these dams will be more serious, which is a serious threat to people’s lives and property downstream. Therefore, the seismic damages and the measures of reinforcement need to be studied. Basic data of 379 reservoirs were at high-risk or at dam-break risk, as well as the damage situations of medium and small earth dams damaged in the Wenchuan earthquake, are collected and presented in this paper. Several main failure modes of earth dams during the earthquake are analyzed and summarized. For practical engineering, some reinforcement measures for the typical failure mode of an earth dam are also proposed. The Wenjiajiao earth dam, a typical medium reservoir in the high-risk category, located in Cangxi County, Sichuan Province, is selected as the analysis example. The dam safety and seismic stability are calculated and analyzed by the finite element software program ANSYS. The results indicate that the biggest permanent deformation caused by the earthquake occurred in the dam crest; the maximum deformation is mainly a downward subsidence of 21.8 cm. As the thickness of the dam top part decreases, the dynamic displacement and vibration velocity of the dam crest increases. This calculation is consistent with the actual situation where the parapet wall of a dam crest was seriously incline and the upper slope collapsed and cracked. The research results can provide a reference for the danger control and reinforcement of similar earthquake damaged reservoirs.