Engineering characteristics of british over-consolidated clays and mudrocks I. Tertiary deposits

Abstract

There is much information in the literature relating to the classification, strength, deformability, permeability and other geotechnical properties displayed by British overconsolidated clays and mudrocks. The opportunity has been taken in this paper to collate published values of the more important geotechnical parameters for a number of Tertiary formations and to present ranges and averages in a convenient form. The data are intended to serve as a reference of typical values of parameters, but it must be recognised that the results were derived from tests on material from particular locations and will not necessarily be typical of formations as a whole. Meaningful interpretation is possible only when there is complete awareness as to why values may vary. Since the degree of weathering is particularly important, values for both weathered and unweathered material are presented, where possible. However, discussion of the data indicates that mineralogical composition, geological loading, present burial depth and method of testing are also significant causes of variation. Some of the implications regarding the choice of design parameters are discussed; of particular relevance is the degree and orientation of fissuring present in the material.