Laboratory testing of undisturbed soft clay samples to determine engineering design parameters

This paper reviews laboratory methods for measuring the stress-strain-strength-flow behaviour of soft clays for determination of design parameters. It describes three levels of testing from simple classification tests to advanced testing for measurement of design parameters. The paper traces some of the major practical contributions of experimental research to our understanding of soft clay mechanical behaviour. Recommendations are given for implementation of these research results in practice with the goal of improving the engineering state-of-the-practice, which often lags well behind the research state-of-the-art. Significant advances in the understanding of clay behaviour have been realized in the past few decades including such issues as the influence of anisotropy, stress history, rate effects, and sample disturbance. Of these issues, sample disturbance remains by far the most difficult one to deal with in practice and in fact is often ignored. It is recommended that evaluation of sample disturbance be considered an essential aspect of any site characterization program.