基于尖端坡降变化的双层堤基渗透破坏通道上溯研究
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摘要
双层堤基渗透破坏集中渗流通道产生后,有继续上溯和保持稳定两种可能,传统方法中外江与管涌口之间的整体水力坡降只能判定渗透破坏发生与否,无法判定已有通道是否会继续上溯。是否继续上溯关键在通道尖端坡降的发展趋势,其根源是尖端土体颗粒在尖端坡降作用下的稳定性。当通道上溯后,其内沿程各处断面会发生冲淤变化,进而影响尖端坡降,在此作用下对尖端处土体颗粒进行稳定性计算,分析在进一步上溯后,尖端坡降的变化趋势。若尖端坡降随着通道的上溯持续增长,则说明该上溯会进一步发展,若通道上溯后尖端坡降维持稳定,则说明该通道不会持续上溯。编制有限元程序,同时考虑通道断面扩展和上溯与尖端坡降之间的相互影响,判定通道发展趋势。有限元程序中,对集中渗流通道断面进行等效代替,以加快计算速度。在室内进行模型试验,观测预设渗流通道的发展,通过数值模拟与室内试验数据对比,证明本理论方法及所编制程序可行可用。
After piping channel appears, the length of the channel may elongate or remains stable. The traditional method is to calculate the hydraulic gradient between river and piping port, and it is not precise enough. In fact, the hydraulic gradient at the tip of the channel determines the results. Considering the effects of the channel expansion, the stability of particles at the tip of the channel is analyzed, and change of the hydraulic gradient at the channel tip after channel elongation is also investigated. If the hydraulic gradient continues to grow with the channel elongation, the channel will be extended. If the hydraulic gradient keeps steady, the channel will be stable. The finite element program is compiled, to simulate the cross-section expansion and up-tracking of the channel. The program speed is accelerated by the equivalent substitution of the channel section for concentrated seepage. The model tests are carried out to observe the development of the piping channel. By comparing with the laboratory test data, it is proved that the theoretical method and the finite element program are feasible and usable.
After piping channel appears, the length of the channel may elongate or remains stable. The traditional method is to calculate the hydraulic gradient between river and piping port, and it is not precise enough. In fact, the hydraulic gradient at the tip of the channel determines the results. Considering the effects of the channel expansion, the stability of particles at the tip of the channel is analyzed, and change of the hydraulic gradient at the channel tip after channel elongation is also investigated. If the hydraulic gradient continues to grow with the channel elongation, the channel will be extended. If the hydraulic gradient keeps steady, the channel will be stable. The finite element program is compiled, to simulate the cross-section expansion and up-tracking of the channel. The program speed is accelerated by the equivalent substitution of the channel section for concentrated seepage. The model tests are carried out to observe the development of the piping channel. By comparing with the laboratory test data, it is proved that the theoretical method and the finite element program are feasible and usable.
引文
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[2]沙金煊.多孔介质中的管涌研究[J].水利水运科学研究,1981(3):89-93.(SHA Jin-xuan.Piping study in porous media[J].Hydro-Science and Engineering,1981(3):89-93.(in Chinese))
[3]刘杰.土的渗透变形特性和控制[J].人民黄河,1984(5):24-28.(LIU Jie.Soil seepage deformation characteristics and control[J].Yellow River,1984(5):24-28.(in Chinese))
[4]屈智炯,吴剑明.压实石碴料渗透变形的试验研究[J].成都科技大学学报,1984(2):67-76.(QU Zhi-jiong,WUJian-ming.Experimental study on seepage deformation of compacted stone[J].Advanced Engineering Sciences,1984(2):67-76.(in Chinese))
[5]陈建生,李兴文,赵维炳.堤防管涌产生集中渗漏通道机理与探测方法研究[J].水利学报,2000(9):48-54.(CHENJian-sheng,LI Xing-wen,ZHAO Wei-bing.Study on piping leakage mechanism[J].Journal of Hydraulic Engineering,2000(9):48-54.(in Chinese))
[6]李广信,周晓杰.堤基管涌发生发展过程的试验模拟[J].水利水电科技进展,2005(6):21-24.(LI Guang-xin,ZHOUXiao-jie.Experimental simulation of the development process of the embankment[J].Advances in Science and Technology of Water Resources,2005(6):21-24.(in Chinese))
[7]张刚,周健,姚志雄.堤坝管涌的室内试验与颗粒流细观模拟研究[J].水文地质工程地质,2007(6):83-86.(ZHANG Gang,ZHOU Jian,YAO Zhi-xiong.Study on mesomechanical simulation of piping with model tests and PFC2D[J].Hydrogeology&Engineering Geology,2007(6):83-86.(in Chinese))
[8]陈建生,张华,王霜,等.多层堤基中土层结构变化对管涌影响的试验研究[J].岩土工程学报,2014,36(12):2213-2219.(CHEN Jian-sheng,ZHANG Hua,WANGShuang,et al.Experimental researches on effect of foundation structure on piping in multilayer embankment[J].Chinese Journal of Geotechnical Engineering,2014,36(12):2213-2219.(in Chinese))
[9]刘昌军,姚秋玲,丁留谦,等.堤基管涌小尺寸模型的细观试验研究[J].水利学报,2014,45(增刊2):90-97.(LIUChang-jun,YAO Qiu-ling,DING Liu-qian,et al.Mesoexperimental research on piping failure with small size model test for dike foundation[J].Journal of Hydraulic Engineering,2014,45(S2):90-97.(in Chinese))
[10]贾恺,曹洪,李兴华.双层堤基管涌通道扩展机制和计算方法研究[J].岩石力学与工程学报,2013(11):2368-2376.(JIA Kai,CAO Hong,LI Xing-hua.Research on mechanism and computational method ofPiping channel expansion of double-layer dike foundation[J].Chinese Journal of Rock Mechanics and Engineering,2013(11):2368-2376.(in Chinese))