Degradation of permeability of ground due to clogging

在本研究中，旨在阐明土壤颗粒外流引起的地面失稳与内部侵蚀机制之间的关系。这里进行了两个实验。首先，通过一维垂直流动地基中土粒流出试验，研究了土粒和花岗岩土的渗透性变化。土粒外溢的发生使地面松散，土粒外溢使地面其他部分致密。最后，部分地面的局部水力梯度增大。其次，采用介电常数式土壤水分计对土壤的渗透性和孔隙度进行了测量。饱和土的体积含水量等于土的孔隙度，因此可以测量射流过程中孔隙度的变化。利用堤下水平流动优势的土槽，测量了孔隙度变化和局部水力梯度。

In this study, it is intended to clarify it about relationship between the destabilization of the ground by the soil particle outflow and the mechanism of the internal erosion. Here, two experiments are conducted. At first, the permeable changes of Toyoura sand and Granite soil are investigated by the test of efflux of soil particles in the one-dimensional vertical flow ground. The occurrence of the efflux of soil particle makes the ground loose, and soil particle effluxed makes other part of the ground dense. Finally, the local hydraulic gradient at the part of the ground increases. Second, authors measure the permeability and the porosity of soil by Dielectric constant-type soil water meter. The volumetric water content is equal to the porosity of soil in saturated soils, therefore, the porosity change can be measured during efflux. With the soil tank that a horizontal flow excels under the levee, the porosity change and the local hydraulic gradient are measured.