变向渗流下的无黏性土颗粒起动机理研究

Non-Cohesive Particles Starting Mechanism Under the Changing Seepage Direction

通过自行设计的变角度模型槽,开展了一系列管涌发生时无黏性颗粒起动试验。研究在不同渗流方向时,水力梯度、渗流流速以及粒径对于细砂起动所造成的影响。试验结果表明:随着渗流方向与重力方向夹角的增大,同一粒径颗粒的临界起动流速以及对应的水力梯度均有增加,试样内部细颗粒通过空隙的难度加大。在同一渗流方向下,随着粒径增大,对应所需要的渗流流速和水力梯度也会相应增大。随着细颗粒不断的从空隙中被带走,试样的整体结构性受到影响,后续的渗流破坏速度会加快,形成了平均宽度由下游至上游变窄的渗流通道。

Through varying angle model slots designed by self a series of non-cohesive particles starting tests were researched.The hydraulic gradient flow velocity and particle size were studied under the different angle between the seepage direction and the horizontal direction. Results show that the incipient velocity and hydraulic gradient of gravel particles increases as the angle between the seepage direction and the horizontal direction. Particles permeating the gap scouring becomes more difficulty.At the same time the incipient velocity and hydraulic gradient of gravel particles increases as the particle size when the angle keeps constant. With the particles being carried out,integral structure of the test sample is affected,it accelerates the seepage velocity and forms seepage channels which the average width narrow from downstream to upstream.