粗粒土淤堵模式判别及最优淤堵粒径区间确定

Clogging types distinguishing of coarse-grained soil and determination of optimal range of clogging grain size

以高原水库坝基松散介质为研究对象，对粒径区间为8--16mm、4～8mm、2-4mm、1-2mm及0．5～1mm的5种样品进行了室内淤堵模拟试验。依据试验结果，提出表层堆积淤堵、内部堵塞以及不淤堵3种模式，其中内部堵塞又分为内部部分孔隙堵塞和表面一内部双重淤堵两种类型，且以表层一内部双重淤堵模式下产生的淤堵效果最佳；得出等效粒径判别法和有效孔隙直径判别法两种粗粒土淤堵模式的判别方法；提出了“特征孔径”的概念，并结合有效孔隙直径判别法，得出5组不同粒径区间材料的特征孔径；将产生表层一内部双重淤堵模式下的粒径区间作为最优淤堵粒径区间，与室内试验中淤堵效果最佳的添加颗粒粒径区间对比，说明有效孔隙直径判别法可直接确定产生最佳淤堵效果的颗粒粒径。

A series of clogging simulation tests in laboratory were conducted on five kinds of samples to re search the clogging effect on permeability of highland reservoir dam, and the grain size ranges of samples were distributed in 8-16mm, 4-8mm, 2-4mm, 1-2mm and 0.5-1mm, respectively. According to the test results, the clogging can be further divided into three types： surface clogging, internal blockage and unclog ging. Then the internal blockage also can be divided into two types： internal partial pore blockage and sur face-internal clogging. It was found that the occurrence of significant clogging is the surface-internal clog ging type. Two kinds of clogging types distinguishing method for coarse grained soil were obtained, and characteristic aperture proposed for different grain size samples was calculated by clogging types distinguish ing with effective aperture of grain. Compared with the range of clogging grain size corresponding to the phenomenon of obvious clogging in indoor test, the optimal range of clogging grain size calculated by effec tive aperture of grain in the condition of the surface-internal clogging was more consistent. It shows that using effective aperture of grain can provide a basis to select the clogging grain size under the different range of grain size.