Visualisation of seepage-induced suffusion and suffosion within internally erodible granular media
Visualisation of seepage-induced suffusion and suffosion within internally erodible granular media
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DOI：
10.1680/jgeot.17.p.161
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发表时间：
2018-10-01
期刊：
影响因子：
5.8
通讯作者：
Bowman, E. T.
中科院分区：
文献类型：
--
作者：
Hunter, R. P.;Bowman, E. T.
研制了一种硬壁“透明土”渗透仪，用于直观地研究向上流动条件下易受渗流作用的散体介质中渗流引起的内部侵蚀的机理。实验用硼硅酸盐玻璃颗粒代替土壤，用光学匹配的油和荧光染料混合代替水。这项被称为平面激光诱导荧光(PLIF)的技术使人们能够在渗透仪内观察到远离墙壁的颗粒和流体的二维平面。试验结果与其他研究人员在具有相似颗粒级配的土壤上的结果非常一致。不稳定材料在低至i=0.25的平均水力坡度下表现出细粒的迁移，而稳定材料最终在接近1的水力坡度下因隆起而失效。负载主要由较粗组分支撑的内部不稳定土壤表现为水淹(细粒迁移而不破坏承载系统)；粗颗粒和细颗粒同时支撑的土壤表现为窒息(即细粒迁移过程中的体积变化)。对一个不稳定的样品进行的定量图像分析显示，如Skempton和Brogan在1994年定义的那样，在接近临界的低水力坡度下，开放的空隙区域在样品中迁移。这发生在外部测量的当地水力坡度开始明显偏离平均值之前。开发的测试技术表明，光学匹配的玻璃和石油的机械行为类似于土壤和水，PLIF技术与图像分析相结合可以提供对内部侵蚀机制的额外洞察。
A rigid-walled 'transparent soil' permeameter has been developed to study visually the mechanisms occurring during seepage-induced internal erosion in susceptible granular media under upward flow. The experiments use borosilicate glass particles in place of soil, and an optically matched oil mixed with fluorescent dye in place of water. The technique known as plane laser-induced fluorescence (PLIF) enables a two-dimensional plane of particles and fluid to be viewed inside the permeameter, away from the walls. Results of tests have provided close agreement with those of other researchers on soil of comparable particle size grading. Unstable materials showed migration of fine grains under mean hydraulic gradients as low as i = 0.25, whereas stable materials eventually failed by heave at hydraulic gradients close to unity. Internally unstable soils where the loads were predominantly supported by the coarser fraction exhibited suffusion (fines migration without disruption of the load-bearing system); those supported by both coarse and fine particles exhibited suffosion (i.e. volume change during fines migration). Quantitative image analysis conducted on one unstable sample showed areas of open void space migrating through the sample at low hydraulic gradients near critical, as defined by Skempton and Brogan in 1994. This occurred before the externally measured local hydraulic gradients began to diverge significantly from the mean. The testing technique developed shows that optically matched glass and oil behave mechanically similarly to soil and water, and that the PLIF technique coupled with image analysis can provide an additional insight into the mechanisms of internal erosion.