Evaluating mass of soil particles eroded into geosynthetic drainage layer in landfill final cover system

摘要

The mass of internal soil erosion adjacent to a geosynthetic drainage material due to precipitation and percolation was evaluated. Down-flow precipitation/percolation tests using a column were conducted on sandy soils under several precipitation intensities. The experimental results showed that there are two patterns which can be differentiated in terms of the masses of soil losses; Entire soil erosion and Locally soil erosion. Entire soil erosion occurred when sufficient precipitation/percolation intensity for the hydraulic conductivity of soil was continuously given, and is attributed to the seepage failure which occurred when the wetting-front reached the bottom of the column specimen and the condition for all the depth of the specimen reached saturation. In contrast, only preferential flow occurred either with insufficient precipitation/percolation intensity or with a limited period of precipitation with sufficient intensity resulting in Locally soil erosion. The formation of the eroded portions depends on the falling droplets. A theoretical method to estimate the magnitude of erosion is proposed based on the balance of weight of the droplet and the capillary force.