堤防管涌产生集中渗漏通道机理与探测方法研究

本文对堤防渗流管涌发生后产生集中渗漏通道的机理进行了深入的分析探讨，在管涌发生初期采用井流理论模拟河水向管涌口补给时地下水的流场情况，确定管涌开始发生时的范围以及逐步的发展过程，根据管涌的临界水力梯度，通过模型可以求出管涌初期的临界面，管涌初期涌砂区的范围较大，由于管涌离堤坝最近的地层中的水力梯度最大，被带走的砂也最多，涌水量增加而水力梯度减小，造成接近管涌初期临界面附近的水力梯度达不到地层颗粒移动的临界水力梯度，造成临界面向里缩小，最终形成了集中渗漏带。本文还对管涌渗漏探测的天然示踪与同位素示踪方法进行了论述。

Study on piping leakage mechanism

In this paper, the mechanism of piping causing concentrated seepage in dyke is studied in depth. In the initial stage of piping, the theory of well flow is applied to imitate the seepage field of river water flowing from piping riser. The affected area of initial piping and its progressively developing process are determined according to the critical sepage gradient. The critical surface of piping can be defined by using the seepage model.At first, the sand rising range and the amount of sands to be flushed out are comparatively larger since the seepage gradient is highest in the vicinity of dyke surface. As piping discharge increased, the seepage gradient will be reduced. As a result, the critical surface draws back inside and a concentrated seepage band formed. The natural and isotope tracer methods for detecting the piping seepage leakage in site are also discussed in this paper.