为揭示不同洪水成因下河流交汇处堤防渗透特性的差异，依托忆马溪流域双河口交汇河段，首先根据伯努利方程推求干、支流上游分别或同时遭遇10年一遇设计洪水时河流交汇处各特征剖面的设计洪水位及水深，在此基础上以交汇处相应特征剖面堤防为研究对象，采用有限单元法对三种设计洪水位下河流交汇处堤防迎水面特征点孔隙水压力、最大渗透比降等渗透特性进行仿真模拟。仿真结果如下：（1）支流遭遇10年一遇设计洪水时，干流水位、水深高于支流，导致干流堤防孔隙水压力、最大渗透比降偏大，同时干流出口处最易发生渗透破坏；（2）干流单独遭遇或干支流同时遭遇10年一遇设计洪水时，支流水位、水深高于干流，导致支流堤防孔隙水压力、最大渗透比降偏大，此时支流出口处最易发生渗透破坏。由此可见，进行堤防防洪抢险时应根据不同洪水成因突出相应的重点防护区。%In order to reveal the differences of seepage characteristics of dikes at River confluence under flood levels of different origins,taking the Shuanghe Confluence of Yimaxi watershed as an example,the design flood levels and depths of River confluence at several typical sections are formulated according to the Bernoulli e-quation under different floods caused by occurrence of 10 years in upstream of mainstream and branch stream separately and at the same time.On the basis of these design flood levels ,the pore pressure of dike heel and maximum seepage gradient at the corresponding typical dike sections under the three different floods are simu-lated by the finite element method at three design flood levels.The simulation results are as follows:(1)When tributary stream encounters the design flood with the occurrence of 10 years ,the level and depth of main stream are higher than tributary streams;pore water pressure and maximum seepage gradient of the dike at mainstream are greater,and it is easiest to cause a failure by seepage at the exit of main stream;(2)When main stream suffered alone,or main stream and tributary streams encounter the design flood with the occurrence of 10 years at the same time,the level and depth of water in tributary stream are higher than main streams;a tributary of the embankment leading to pore water pressure drop larger than the maximum penetration ,then the most likely to occur at the outlet tributary infiltration and sabotage.Thus the conduct dike flood rescue should highlight the appropriate focus of protection ,depending on the causes of the flood zone.
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