A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1982

A study on the effect of drain resistance on the rate of consolidation of soils with vertical drains was conducted experimentally as well as analytically. the experiments which were named the Vertical Drain Model Tests, were carried out in a Rowe Oedometer Apparatus, having an inner diameter of 6". The tests were carried out on undisturbed samples, having thickness of 2". In order to force the excess pore water pressure to dissipate radially, vertical drain, having a diameter of 0.5" was installed at the center of each sample. The drain materials used were composed of mixtures of sand - dry clay powder with different proportions by weight, to obtain drain materials with different permeabilities. Permeability tests for each drain material were conducted in a Triaxial apparatus. With this method, it was possible to measure the coefficient of permeability of each drain material at different axial effective stresses. The results of the Vertical Drain Model Tests were compared with the analytical solutions available, based on the free strain theory and the equal strain theory. Finite difference method was used to solve the analysis based on free strain theory. A computer program has been prepared for this purpose. For the equal strain theory, the formula developed by HANSBO (1979) was used. In both analysis, the effect of drain resistance and variations of consolidation parameters during consolidation process were included. A good agreement between the experimental results and the results of the analysis has been obtained.