Case histories involving volume change and shear strength of residual soils

Abstract

Chapters 1 to 7 have described the origin and formation of residual soils and how their behaviour and properties differ from those of transported soils. The index properties of residual soils and the difficulties and pitfalls attendant on their measurement have also been set out, in addition to methods of classifying these materials. This was followed by a description of site exploration, profile description and sampling methods suitable for residual soils. Because residual soils very often, even most often, occur in semi-arid to arid climates where the wet and dry seasons are clearly demarcated, many residual soils exist in a seasonally or permanent state of unsaturation and even desiccation. For this reason, the concepts and methods of unsaturated soil mechanics were very early introduced and integrated into the descriptions given in each chapter. Two more technical aspects of residual soil mechanics followed, namely compaction and the mechanics of compacted residual soils, and permeability and fluid flow through saturated and unsaturated soils. These led to the two most extensive chapters, on compressibility, settlement and heave and also shear strength behaviour and the measurement of shear strength. Because Geotechnical Engineering is a science practised both in the laboratory and the field, most of the impetus for laboratory or field research, as well as for the development of new engineering methods of construction and materials has come from the need to solve practical problems in design, construction and remedial work. It is therefore appropriate to end the book by describing a series of case histories that illustrate applications of the techniques described earlier to the solution of practical geotechnical problems. In order of appearance, the case histories will describe the following: