摘要
深厚低渗透土层天然地基上的土石围堰基础中,常常需要采用碎石桩等处理措施缩短固结排水距离,以控制堰基超孔隙水压力的累计幅度,加速其消散速度,从而减小堰基的变形,提高防渗体系的结构安全性和堰基的抗滑稳定性。基于拉哇水电站上游围堰设计论证和优化的需要,发展了围堰填筑和基坑开挖全过程渗流与应力变形耦合的二维和三维有限元仿真方法,并在LinkFEA软件中实现,成功用于拉哇上游围堰的计算分析。主要基于二维模型,介绍了二维模型中考虑三维绕渗效应、耦合计算中水中填筑与开挖边界条件处理、防渗墙与碎石桩施工仿真,二维模型中碎石桩与土复合地基的等效概化、低渗透土层的渗透系数随着压密而变化模拟等方面的方法,进行了拉哇上游围堰从地基初始应力计算、土体填筑与结构物施工、基坑开挖的全过程的渗流与应力变形的耦合计算,并对围堰戗堤填筑完成和堰体填筑完成两个典型时刻堰基的孔隙水压力、位移和土层与桩中的应力情况进行了分析。
The deep low permeability layers in earth-rock cofferdam foundation often need to use the treatment measures such as gravel piles to shorten the distance between consolidation drainages to control the cumulative quantitiy of the excess pore water pressure and to speed up its dissipation rate so as to reduce the deformation of dam foundation and improve the security of the seepage control system and stability against sliding of the dam foundation. Based on the needs of the design demonstration and optimization of the upstream cofferdam of Lava Hydropower Station, the 2 D and 3 D finite element simulation methods for the coupling of seepage and stress deformation in the whole process of cofferdam filling and foundation pit excavation are developed and implemented in the software LinkFEA, and are successfully used in the calculation and analysis of the cofferdam. The coupled simulation method for seepage and deformation of saturated soil foundation including gravel piles and its key simulation techniques are introduced, and the simulation of soil filling in water and construction of cutoff wall and gravel piles in the coupled calculation as well as the simulation of the permeability coefficient of low permeable soil layers changing with the compaction is realized. The pore water pressure and displacement at two typical stages are analyzed, and the variation characteristics of pore water pressure, stress and displacement are described.
作者
吴梦喜
宋世雄
吴文洪
WU Meng-xi;SONG Shi-xiong;WU Wen-hong(Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China;Power China Hydropower Zhongnan Engineering Corporation Limited,Changsha 410014,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2021年第4期613-623,共11页
Chinese Journal of Geotechnical Engineering
关键词
渗流
变形
有限元
固结
耦合模拟
seepage
deformation
finite element
consolidation
coupled simulation
