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Unsaturated soil mechanics has undergone tremendous amount of research both in field and laboratory creating new concepts and theories for practicing engineers. The behavior of unsaturated soil in the field is very sensitive to the flex changes of ground water table and rainfall infiltration. This research covers in depth the study of unsaturated residual soil behavior in both laboratory and field. Various research tools were used to measure important data such as matrix suction, rainfall records, infiltration rate, surface runoff, unsaturated and saturated soil shear strength and soil moisture characterizes. The basics of this study is to perform full scale research on every aspect of unsaturated soil theory by performing site investigation, laboratory testing, field instrumentation, field rainfall simulation experiment and computer analysis. All the data are compiled to conclude the influence of rainfall infiltration on insitu soil shear strength, drop in matric suction with time and the effect on slope factor of safety during rainfall.

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Ir.Dr.Saravanan Mariappan is the principal engineer of Nexus Engineering Consultant. He has undertaken projects related to structural and geotechnical works. He received his B.Eng.(Civil) and M.Eng.Sc. from University Malaya, Malaysia and PhD from Kyoto University, Japan. He has authored numerous articles on matrix suction, landfill liner and slope.

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