1.3 Outline of the Book

This book is composed of seven chapters.The organization of the book is introduced below:

Chapter 1 gives a brief introduction of this research study and the book.

In Chapter 2 a literature review is given based on the non-coaxiality of the directions of principal stresses and principal strain increments,and the background of hollow cylinder apparatus.Previous studies on non-coaxial soil behaviour are presented including both numerical and experimental work.Particular attention is focused on the investigation of non-coaxiality using a hollow cylinder apparatus.The principles of the hollow cylinder apparatus and the effect of specimen geometry is discussed in this chapter as well.

Chapter 3 introduces the details of the testing system,including the hollow cylinder apparatus and control software,followed by the physical properties of the tested materials.The specimen preparation and test procedures are also described.Then validation experimentation to check the test equipment and speicmen repeatability are presented.

Chapter 4 focuses on the results of monotonic loading tests on Portaway sand.Fourteen tests are designed on two densities following various stress paths to study the non-coaxiality of soil behaviour when specimen subjected to monotonic loading in a fixed principal stress direction.The effect of relative density is also discussed.

Chapter 5 describes the test results of pure rotation tests on Portaway sand and Leighton Buzzard sand.Ten tests are presented in this chapter.The general soil behaviour is described first,followed by discussion of the non-coaxial soil behaviour.Results are compared between densities and different materials to study the influence of density and specimen anisotropy.

Chapter 6 contains the results of two tests subjected to the combined loading.The effect of stress path on non-coaxiality is discussed in this chapter.

Chapter 7 summarises the main outcome of the research and gives some suggestions for future work.