| Summary: | 碩士 === 國立成功大學 === 土木工程學系碩博士班 === 95 === A theoretical model for predicting effluent ratios (qt) and total effluents (Qt)in geosynthetic dewatering systems is established based on a series of falling head dewatering column tests using a silt-water mixture and four types of woven geotextiles reported by Huang and Luo (2007). Key elements of this model include :
(1) Permeability of the geotextile dewatering system is dictated by the hydraulic properties of soil cake deposited at the upstream of the geotextile,the influence of original permeability of the geotextiles to the permeability of geotextile dewatering systems is relatively small.
(2) Permittivity of the soil cake decreases non-linearly with the increase of the height of soil cake.
(3) The time for attaining final soil cake heights can be determined based on the descending of the particles, D6 and D10, to the level of final cake heights calculated based on the total volume of the suspended particles and the void ratio vs. cake heights relationship obtained in the tests. It is found that the experimental values of qt and Qt fell between the lower and upper bounds calculated using the proposed model for a major part of the test condition examined. For the test using a relatively small initial water height, Ho (=100 mm), the proposed model provided satisfactory values of qt, while provided under-estimated values of Qt due partially to the assumption on the permeability of the soil cake at early stage of cake formation, and also due partially to the relatively large error associated with the test with a relatively small initial water height.
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