Effluent Analyses of Geotextile Dewatering Systems

Abstract

A theoretical model for predicting effluent rates(qt) and cumulative effluent volume (Qt) in geotextile dewatering systems is established based on the a series of falling head dewatering tests(FHDT) using two reservoir sediments and four types of woven geotextiles similar to the ones reported by Huang and Luo (2007). The experimental results obtained from these series of FHDT were also presented and vital parameters obtained from the test were used for predicting the analytical results with the model. The predicted performance was compared with laboratory observations. Two particle travel velocities were incorporated in the model used to determine the particle settling velocity at given time (Stokes and Gibbs). It has been found that final cake height can be calculated based on the total volume of the suspended particles and the time-dependent void ratio. It is also found that, the final cake height is influenced by the time-dependent void ratio rather than the change in the hydraulic conductivity of the soil. The model gives a closed prediction of the experimental results of qt and Qt better with upper bound ksoil(permeability of soil cake) and the particle size D50 while lower prediction were obtained with lower bound ksoil and particle size D10 regardless of the change of the initial water height. Also the simulation with Stokes equation gives more agreeable results to the measured data compared to equation given by Gibbs et al (1971) for most of the cases examined.