1.2 Research Objectives

A new hollow cylinder apparatus commissioned from GDS Instrument Ltd.was being used in this project.The ultimate goal of this project is to provide an understanding of non-coaxial soil behaviour using HCA testing.The aims of this project can be stated as:

1)To evaluate the new HCA system in Nottingham Centre of Geomechanics and design possible testing stress paths.

2)To gain a good understanding of the soil behaviour under various stress paths by testing on Portaway sand.

3)To analyze the stress-strain response from the tests and study the non-coaxial soil behaviour.

4)To study the factors that affect the degree of non-coaxiality by employing various stress paths,different specimen void ratios and different materials,which were Portaway sand and Leighton Buzzard sand.

The following specific objectives are required to achieve these aims:

1)A literature review on the non-coaxial soil behaviour and HCA testing methods.

2)Determination of physical characteristics of the Portaway sand and Leighton Buzzard sand.

3)Experimental tests to understand the equipment well and to use the control software confidently,as well as for the validation of the testing program.

4)Design stress paths for the HCA experiments.

5)Analysis of the experimental results to obtain the relationship between principal stresses directions and principal strain increments directions.