针对我国部分坝址覆盖层深厚、地质条件复杂且适宜就地取材的工程背景,发展安全可靠的新型筑坝技术与环境友好型材料,以提升新建大坝抵御极端灾害的“韧性”,具有重要的工程意义。提出采用结构化胶结技术对传统堆石坝坝面散粒体进行处理,使其形成具有一定强度与整体性的结构化胶结材料。基于50∶1比尺的水槽溢流冲刷模型试验,系统探究了入流量、胶结深度及胶结范围对胶结堆石坝漫顶冲刷演化规律的影响。研究结果表明:与普通堆石坝相比,胶结堆石坝可有效延缓溃坝进程并显著减小峰值溃决流量。当胶结深度为堆石粒径D的2~2.5倍、表面胶结占比达到0.603时,胶结堆石坝在相同入流量条件下,相较于普通堆石坝可将峰值溃决流量降低约5%,峰值流量出现时间延后约230%,溃坝历时延长可达74%。若进一步将坝面胶结占比提高至0.855,甚至可实现漫顶不溃。当胶结深度继续增至(3.5~4)D时,虽无法进一步推迟峰值流量的出现时间,但仍能减小峰值流量并延长溃坝历时;然而,胶结深度超过此范围后,对抗冲缓溃能力的提升已不明显。本研究结果可为大坝的韧性设计及除险加固提供理论依据与技术支撑。

[Objective] To improve the resistance of conventional rockfill dams to overtopping erosion and mitigate the consequences of dam breaching, this study proposes a structured surface cementation technique for rockfill dams. By cementing the loose granular material on the dam surface, a protective cemented layer with sufficient strength and structural integrity is formed. This study aims to investigate the effects of inflow discharge, cementation depth, and surface cementation area on the overtopping erosion and breach evolution of cemented rockfill dams, determine appropriate cementation parameters, and evaluate the feasibility of this technique for resilient dam design and risk-mitigation retrofits of existing rockfill dams. [Methods] A series of 1∶50-scale flume model tests on overtopping erosion was conducted on conventional and cemented rockfill dams. The experimental program included different inflow discharges, cementation depths, and surface cementation area ratios. The cementation depth was normalized by the characteristic rockfill particle diameter D and the surface cementation area ratio was defined as the ratio of the cemented surface area to the corresponding total dam surface area. The results for conventional and cemented rockfill dams under identical inflow conditions were compared to evaluate the effectiveness of the surface cemented structure in delaying erosion, reducing peak discharge, and preventing dam breaching. [Results] Structured surface cementation significantly altered the overtopping erosion and failure processes of rockfill dams. Compared with conventional rockfill dams, cemented rockfill dams exhibited markedly slower surface erosion, longer breach durations, lower peak breach discharges, and delayed times to peak breach discharge. When the cementation depth was (2-2.5) times the characteristic rockfill particle diameter D and the surface cementation area ratio reached 0.603, the peak breach discharge of the cemented rockfill dam was reduced by approximately 5%, the time to peak breach discharge was delayed by approximately 230%, and the breach duration was extended by up to 74% under the same inflow discharge conditions. When the surface cementation area ratio was further increased to 0.855, the dam was able to withstand overtopping without breaching. When the cementation depth was increased to (3.5-4)D, no further delay in the time to peak breach discharge was observed; however, the peak breach discharge was further reduced and the breach duration was prolonged. Once the cementation depth exceeded this range, further increases produced no significant improvement in erosion resistance or breach-mitigation performance. [Conclusions] Structured surface cementation can effectively enhance the overtopping resilience of rockfill dams. By transforming the erosion-prone loose granular surface into an integrated protective structure, the proposed technique restrains particle movement, slows the propagation of erosion into the dam body, and delays the breaching process. The surface cementation area is a key parameter governing the overtopping failure mode of the dam. A sufficiently large cemented area can change the failure mode from progressive breaching to overtopping without breaching. Increasing the cementation depth also improves the erosion resistance of the dam. However, the marginal benefit gradually decreases when the cementation depth exceeds approximately (3.5-4)D. Therefore, both the surface cementation area and cementation depth should be rationally determined in engineering design. The proposed technique provides a potential approach for enhancing the resilience of new and existing rockfill dams in regions with thick overburden layers, complex geological conditions, and a preference for using locally available rockfill materials. The findings provide experimental evidence for reducing peak breach discharge under extreme overtopping conditions, extending the time available for emergency response, and supporting risk-mitigation design for rockfill dams.