Dam safety |
Designing earthquake- resilient temporary dam works
Despite growing hydropower development in seismically active regions, no international
standard governs the seismic design of river diversion works. Chongjiang DU examines current practice, highlights critical design gaps, and proposes risk-based criteria and thresholds to ensure safer cofferdams and temporary diversion structures during dam construction
Right: Huang and Liu3 reported
severe damage to temporary works at Upper Trishuli-3A hydropower project in Nepal during the 2015 Gorkha earthquake (magnitude of 7.8), which occurred while the project was under construction. Image courtesy of ELC Electroconsult
WORLDWIDE, THERE IS CURRENTLY no recognised standard or code governing the seismic design of river diversion works in dam projects, leaving a significant gap in dam engineering practice. As a result, seismic actions on temporary structures such as cofferdams and diversion facilities are frequently treated inconsistently – or ignored altogether – even in regions of high seismicity. This article examines this design deficiency by focusing specifically on the seismic design of river diversion works. Commonly adopted approaches for cofferdams and other temporary structures are reviewed and critically assessed, and a practical threshold for when seismic actions should be considered is proposed. Using peak ground acceleration interpolation from Eurocode 8 alongside probability-of-exceedance risk analysis, the seismic criteria currently applied in practice are evaluated and their associated risks quantified. The article recommends aligning seismic design criteria for temporary works with those used for flood design, and discusses the accuracy and practical limitations of the Eurocode 8 interpolation method when applied to construction-phase structures.
24 | January 2026 |
www.waterpowermagazine.com
1. Introduction A construction earthquake (CE) is defined as a seismic
event considered specially for the design of temporary structures during the construction period. Among various temporary structures, this paper focuses primarily on river diversion works, including cofferdams, diversion tunnels, diversion channels and culverts. These structures enable dewatering of the construction site of the main permanent dam, temporarily creating dry land and protected working conditions throughout construction.
Although cofferdams are typically much smaller than the main dam and the risk exposure period is only the construction period of the main dam, the potential risk to downstream communities must not be underestimated. The temporary nature of these works should not negate the need for rigorous engineering. Rather, appropriate dam engineering principles must be applied to their design and construction to ensure safety and to manage seismic risk during the construction of the main dam. This is signifcant, as seismic loads can impact both the internal and external
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