Initiation and development of water film by seepag

Authors: Xiaobing Lu Peng Cui Kaiheng Hu Xuhui Zhang

Publish Date: 2010/11/09

Volume: 7, Issue: 4, Pages: 361-366

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Abstract

When water seeps upwards through a saturated soil layer the soil layer may become instability and water films occur and develop Water film serves as a natural sliding surface because of its very small friction Accordingly debris flow may happen To investigate this phenomenon a pseudothreephase media is presented first Then discontinuity method is used to analyze the expansion velocity of water film Finally perturbation method is used to analyze the case that a water flow is forced to seep upwards through the soil layer while the movement of the skeleton may be neglected relative to that of water The theoretical evolutions of pore pressure gradient effective stress water velocity the porosity and the eroded fine grains are obtained It can be seen clearly that with the erosion and redeposited of fine grains permeability at some positions in the soil layer becomes smaller and smaller and the pore pressure gradient becomes bigger and bigger while the effective stress becomes smaller and smaller When the effective stress equals zero ef liquefaction the water film occurs It is shown also that once a water film occurs it will be expanded in a speed of Ut/1 − ɛ

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