为明确混凝土高趾墙复式结构对特高面板坝力学性能的改善效果,依托国内在建的某250 m级特高面板坝工程,分别采用二维和三维非线性有限元方法,比较了采用混凝土高趾墙复式结构和常规结构2种设计方案时大坝应力变形的差异性。结果表明:混凝土高趾墙显著抑制了堆石体顺河向变形,堆石体上游向变形最大减幅为23%,面板挠曲变形明显降低,挠度极值降低10%;大坝施工分层填筑及多级蓄水过程堆石体内部应力分布平整,应力水平较低,无应力集中与塑性极限状态区域;面板、混凝土高趾墙所受压应力均在混凝土抗压容许值范围内,变形值在工程合理范围内。研究结果进一步论证了特高面板坝采用复式结构方案的合理性与安全性,为同类高坝工程的结构优化设计提供了理论依据与技术参考。

[Objective] With advances in dam construction technology and equipment, faced rockfill dams have emerged as a highly competitive dam type. The development of concrete-faced rockfill dams (CFRDs) in China is progressing toward the goal of “taller dams and larger reservoirs.” For ultra-high CFRDs, a gravity-type concrete high toe wall is incorporated at the upstream heel area of the riverbed, replacing a portion of the lower face slab. This not only reduces the face slab length but also improves maintainability in the lower dam zone. This study aims to further evaluate the rationality and safety of adopting this composite structural scheme for ultra-high CFRDs. [Methods] An ultra-high (250m) CFRD under construction in China was taken as the research subject. Two-dimensional nonlinear finite element analysis was employed to compare the stress and deformation differences between the composite structure with a concrete high toe wall and the conventional structural scheme. A three-dimensional nonlinear finite element model was further applied to examine the mechanical behavior of the composite-structure ultra-high CFRD during staged construction filling and multi-level reservoir impoundment. The rockfill was modeled using Shen Zhujiang’s double-yield-surface elastoplastic constitutive model, while concrete structures—including the face slab, toe slab, and riverbed high toe wall—were simulated with a linear elastic model. Interfaces between rockfill and concrete were modeled using thin-layer elements with low modulus. [Results] The concrete high toe wall significantly restrained the streamwise deformation of the rockfill, reducing the maximum upstream deformation by 23%. Face slab deflection was notably decreased, with a 10% reduction in peak deflection. During staged filling and multi-stage impoundment, the internal stress distribution in the rockfill remained uniform, with low stress levels and no evidence of stress concentration or plastic limit zones. Compressive stresses in the face slab and concrete high toe wall were within the allowable compressive strength of concrete, and all deformations fell within acceptable engineering limits. [Conclusions] (1) The composite “concrete high toe wall-faced rockfill dam” structure, which replaces the lower face slab in the riverbed with a gravity concrete wall, effectively restrains streamwise rockfill deformation, reduces face slab deflection and improves its stress distribution, while also enhancing maintainability at the slab bottom. This scheme provides a new research direction for CFRD construction and merits further promotion and application. (2) Validation and wider adoption of novel dam structural schemes require support from field monitoring data. This study only considered the stress-deformation behavior of the composite-structure CFRD under static water load. In practice, stress and deformation in faced rockfill dams involve complex conditions such as dynamic actions, seepage, and multi-field coupling. The actual performance and feasibility of the composite structural scheme still need to be verified by long-term operational monitoring data from the project.