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利用显微摄像可视化跟踪技术、数字图形的计算机实时处理技术,开展室内小尺寸堤基管涌物理模型的细观试验研究。从细观角度研究堤基管涌发展过程中的渗流过程、水头、管涌通道前端的颗粒运动、颗粒含量和水力梯度等参数变化的动态变化过程。研究结果表明:(1)堤基管涌的渗透破坏分为三个阶段,无明显渗透变形阶段、管涌通道形成阶段和堤基溃堤阶段;(2)从细观试验结果可看出,在无明显渗透破坏阶段,粒径小于0.075mm颗粒发生移动现象,稍大颗粒发生转动,但骨架颗粒没有变化。随着水力梯度的增大,当达到砂样的临界水力梯度时,砂样局部薄弱处的骨架颗粒发生移动,形成管涌通道并逐渐向上游扩展;(3)管涌通道前端的颗粒起动水头随粒径大小而不同,粒径越大,起动的临界水头越大;(4)管涌的发展是不断调整变化的,形成蜿蜒枝状沟道,主要原因是砂样颗粒的细观分布具有很大随机性,细颗粒流失形成的孔隙会被粒径大的颗粒填充,同时,也会引起周围更多的细颗粒流失使管涌通道变大。
Using the micro-camera visualization tracking technology and digital graphic computer real-time processing technology, the micro-scale experimental research on the physical model of indoor small-sized embankment pipe is carried out. From the microscopic point of view, the dynamic process of seepage process, head movement, particle movement at the front of the piping channel, particle content and hydraulic gradient were studied during the development of embankment pipe. The results show that: (1) The infiltration and destruction of the embankment pipe is divided into three stages with no obvious infiltration and deformation stage, the formation of piping passage and the embankment dike stage. (2) According to the results of the meso-scale test, Significantly infiltrated the destructive stage, particle size less than 0.075mm particles move, slightly larger particles rotate, but there is no change in the skeleton particles. With the increase of hydraulic gradient, when the critical hydraulic gradient of sand sample is reached, the skeleton particles in local weak sand sample move to form the tube channel and gradually expand to the upstream. (3) (4) The development of pipe piles is constantly changing and changing to form meandering dendritic channels, mainly due to the fact that the fine-grained distribution of sand-like particles is very large Randomness, the formation of fine particles lost pores will be filled with large particles, but also will cause the surrounding more fine particles of the loss of piping channels become larger.