A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering at the Asian Institute of Technology, Bangkok, Thailand.

Thesis (M.Eng.) - Asian Institute of Technology, 1973

A study of the effect of soil structure on dilatation was carried out on an artificially sedimented kaolinite clay. Various soil structures were produced by the use of different pore fluids i.e. distilled waters, sodium chloride and sodium hexametaphosphate. Conventional isotropically consolidated undrained triaxial compression tests with pore pressure measurements and oedometer tests were conducted in the investigation. In the oedometer tests, two samples for each soil were consolidated anisotropically at 320 psi and then rebounded at unloading ratios of 1.5 and 3.0 respectively. In the triaxial tests, the samples for different soil structures were first consolidated to a maximum past pressure of 120 psi and then allowed to swell under smaller consolidation pressures prior to shear. It was observed that the magnitude of rebound decrements did not affect appreciably the stored strain energy. The strength of the bonds and the tendency of the soil to dilate increased with higher over consolidation ratios. The greater the amount of locked in strain 'energy released after failure of interparticle bonds, the greater would be the tendency of the soil to dilate. Furthermore, it was observed that the dispersed soil, with weaker bonds, exhibited slightly greater tendency to dilate than those of the flocculated soils.