Development of Prediction Method with Numerical Calculation and Clarification of Mechanism of Failure in Foundation of the Hydraulic Structure

利用蠕变理论推导出的蠕变长度，对堰下透水地基渗流破坏进行了稳定性分析。由于这是一种简单的经验性方法，不能反映基础随堰上下游水头增大而发生的变形过程。本研究开展了一系列渗流破坏模型试验，并将试验结果应用于弹塑性有限元分析，重新考虑渗流破坏问题。所得模型试验结果表明，用蠕变长度计算渗流破坏的临界水头是不正确的。分析结果表明，Terzaghi方法适用于堰下地基渗流破坏临界水头的计算。

The stability analysis for seepage failure of pervious foundations under a weir has been conducted by means of the creep length derived from the creep theory. As this is a simple method developed empirically, it does not show the deformation process of the foundations along with the increase of the water head between upstream and downstream of the weir. In the present study, series of model tests of seepage failure were carried out and the test results were applied to elasto-plastic finite element analysis to reconsider the seepage failure problems. The obtained model test results showed that the critical water head for seepage failure could not be correctly evaluated by the creep length in the previous theory. The analysis results suggested the applicability of Terzaghi's method to evaluate the critical water head for seepage failure of foundations under a weir.