Contributions in geotechnical engineering: Soil mechanics and foundation engineering

Abstract

This paper summarizes the author’s contribution to Soil Mechanics and Foundation Engineering while at the Asian Institute of Technology (AIT) for over twenty years. It describes the research work carried out on coastal deposits of soils, and in particular the Bangkok sub-soils, in relation to infra-structure development. It draws extensively upon thesis research carried out by graduate students in the field of Soil Engineering at AIT. The Engineering behavior of the Bangkok sub-soils are analysed in terms of Critical State Soil Mechanics concepts and the results of analyses were then used in numerical solutions related to Highway Embankments, Deep Foundations and Deep Excavations. Deterministic numerical analyses were carried using finite element methods with inputs of the soil properties as required by Critical State Soil Mechanics. These data were then compared with the values computed from the traditional analysis. Higher order statistics and simple probabilistic analysis were also combined with the finite element methods to obtain more meaningful parameters that would allow engineers to make better judgments than using traditional safety factors. Various types of ground improvement techniques are described and the use of polymer grids in shallow reinforcements and the use of surface and deep seated chemical stabilisations which involve lime and cement additives are recommended. The use of proper in-situ tests such as the piezo-cone, the pressuremeter and the dilatometer is strongly advocated in comparison to the traditional dominant role played by the Standard Penetration Tests. Promising areas for research and developments are also touched upon: these include the use of the Centrifuge in pollution control; liquefaction studies and accelerated tests of a week duration in time scale, realising the effects of several hundred years in the field. Non-traditional, problematic soils, natural mixed gradational soil deposits, and soft rocks could dominate the research work in the next decade to re-examine the empirical conclusions which appear in routine soil mechanics text based on the experiences of saturated and well behaved soils.