管涌发生发展过程的细观试验研究

Meso-laboratory Study on Initiation and Evolution of Piping

利用显微摄像可视化跟踪技术进行了管涌模型试验,从细观角度观察到了管涌从开始到破坏的整个过程。较详尽地分析了管涌过程中颗粒的移动规律及通道的形成特点,表明骨架颗粒,可动颗粒以及与水之间的相互作用行为贯穿管涌发展的全过程。结合伯努里方程和临界牵引力理论,得到了基于临界速度的临界水力梯度公式;基于试验数据,从孔隙率对临界水力梯度的敏感性角度验证了模型的有效性,表明在分析孔隙率对临界水力梯度的影响度时,该模型优于太沙基模型。

Using micrographic visual tracing technique, model tests on piping are carried out. The process of piping from initiation to failure is observed. The moving rule of the particle and formation of leakage passage are analyzed in detail. The results indicate that the interaction of primary fabric and movable particles and fluid exists through the whole piping process. Coupling the Bernoulli＇ s equation and critical tractive stress theory, a critical hydraulic gradient model based on critical velocity is developed. Based on the experimental data, the adequacy of the model is evaluated. It turns out that this model is superior to Terzaghi＇ s model in explaining the dependency of critical gradient on porosity.