深厚覆盖层上高面板坝建基条件及防渗设计综述

A review of foundation condition and design scheme for seepage prevention system of high CFRD built on deep alluvium deposit

覆盖层上修建混凝土面板堆石坝具有简化施工导流、缩短工期和节省投资等优点,但这类工程大坝防渗系统复杂,防渗系统的应力和变形控制是工程的关键。随着工程经验的积累和技术的发展,我国相继建成了那兰、察汗乌苏、九甸峡、苗家坝、老渡口等多个百米级趾板位于覆盖层上的高面板堆石坝,并有多座百米级深厚覆盖层上高面板坝处于在建和待建状态。覆盖层上高面板坝防渗系统应力变形特性与覆盖层的力学特性及防渗系统的设计关系密切,结合已建和在建的工程资料和研究成果,对覆盖层上高面板坝的建基条件和防渗系统设计进行总结,以期为类似工程设计提供借鉴,并为这一坝型的进一步发展提供技术支撑。总结分析结果表明,如果河床覆盖层变形模量达到40 MPa以上,覆盖层上百米级至150 m级面板坝防渗系统的强度和变形能够满足要求。

CFRD built on deep alluvium deposit has the advantages of simplified cofferdam, shortened construction period and less investment. These types of dams are built with complex seepage prevention systems, and the key problem is to control the stress and deformation of the seepage prevention system of the dam. Thanks to accumulating of engineering experience and developing of technique studies, there have been built many CFRDs such as Nalan, Chahanwusu, Jiudianxia, Miaojiaba and so on on deep alluvium deposit, and many dams are going to be built on the same deposit. The behavior of the stress strain of the seepage prevention system is related to the bearing capacity of the alluvium deposit and the design of the seepage prevention system obviously. Based on the engineering information and research results, this paper has summarized the foundation conditions and the seepage prevention system of those concrete faced roekfill dams built or to be built on the deep alluvium deposit. It can be used for reference in designing similar projects, and can provide technique supports for the development of this type of dams. The results show that if the deformation modulus of the alluvium deposit exceeds 40 MPa, the stress and deformation of the seepage prevention system of those CFRD built on the deep alluvium deposit with the height of 100 m to 150 m can be in the permitted range in the future.