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

Thesis (M.Eng.) - Asian Institute of Technology, 1989

In this study , deformation and flow parameters were determined by inverse analyses using two tes·t embankments improved with prefabricated vertical drains and granular piles. Asaoka{u2022}s method based from Barron's Theory was used with some modifications from Hansbo ' s Theory to take into account of the effect of smear in the case of embankment on vertical drains. The back- analyzed parameters (Eu , Ch and Cv ) were used to predict the amount and rate of settlements. Excellent agreements were obtained in the case of One Dimensional (Oedometer ) , Skempton- Bjerrum and Asaoka ' s methods . One-Dimensional method with inclusion of initial settlement over estimate the predictions. For the embankment on granular piles, inverse analysis was carried out in two stages. Good agreements were obtained on the predicted amount and rate of settl~ments by Asaoka and Balaam ' s methods on the final stage loading al though both slightly overpredicted at the initial stage loading. The equilibrium method always over estimate the predictions. Inverse analyzed Ch r1e 1d / Ch 1ab is about 1.5 to 4.0, Cvr1e1d/Cv1ab is between 1. 3 to 12 and Eu /Su is 150 . ·The back-analyzed C11 value is about 4.90 t / m2 {u2022} Consolidation tests and fi e ld vane tests showed an improvement in shear strength and analysis using three different methods of stress distributions showed that the embankment on vertical drains is now normally consolidated and is undergoing secondary compression while the embankment on granular piles is still undergoing primary consolidation and is about to be normally consolidated. The preconsolidation pressures obtained from EOP-24hr consolidation tests are 5% to 10% higher than those obtained from conventional tests . Very high preconsolidation pressures are obtained from EOP Loading tests which can be finished in 15 to 180 minutes. Laboratory model test on clay sample improved with granular piles showed a decrease in n value with the increase in loading magnitudes. The settlements in slow tests indicate that the reduction in settlements are reduced by about 30% as compared with that of quick tests. Greater settlement reduction is obtained for higher area ratio and using gravels as granular pile materials.