长江干堤双透水堤基渗流稳定有限元分析

Fem Analysis of Dike Foundation Seepage Stability of the Changjiang River Main Levees

利用饱和稳定渗流理论,对长江干堤典型的双透水堤基天然状态、采取水平防渗措施、采取垂直防渗措施的渗流场进行了有限元数值模拟,根据各计算工况下的总压力水头、渗透流速和水力梯度等值线图的对比分析,研究了这种工程地质条件下的堤坝渗流稳定性,研究发现单一渗流控制措施很难彻底解决所有渗流稳定问题,并最终确定垂直防渗措施为单一防渗措施条件下控制效果最好的方法。在此基础上,设计了综合防渗措施,并用数值方法检验了其合理性,经分析其渗流场,发现采取垂直措施、堤后戗台和沙壤土堤后盖重等措施所有渗流不稳定的因素都得到了有效控制。

Typical double-permeable dike stratum of the Yangtze River main levee is studied by the saturated stable seepage theory. The seepage field of the dike under conditions of natural status, horizontal seepage control and vertical anti-seepage measure is simulated by FEM. Based on the comparison of magnitude contours of total water pressure head, seepage velocity and hydraulic gradient under different computation schemes, the seepage stability of the dike is analyzed. It is found that it is hard to solve the problem of seepage by single anti-seepage measure and that the vertical seepage-control measure is the best of all single measures. Furthermore, the comprehensive anti-seepage measure is designed, and the reliability is simultaneously tested by numerical method. Finally, it is found that all seepage stability problems are solved by taking measures of vertical control, setting platform behind dike, and weightloading behind the dike of sandy loam soil.