UNDRAINED STRENGTH CHARACTERISTICS OF NORMALLY CONSOLIDATED AGED CLAY

Soft clay deposits have generally been aged for hundreds to thousands of years since deposition and consequently they possess an additional strength developed by aging effect. Because of this additional strength, soft clay deposits are usually in an overconsolidated state even though they have not been subjected to release of the overburden. This type of clay is so called normally consolidated aged clay. Undrained strength characteristics of this type of clay are discussed in detail in this paper. Fundamental concept required for evaluating the properties of clay subjected to aging effect is first presented and a method to evaluate the effect of aging is indicated. Undrained strength of normally consolidated aged clay in terms of both total and effective stresses are discussed and various characteristics obtained are presented. Discussions are also given to the stress-strain behaviour and the k0 value of this clay. It is demonstrated that these characteristics of clay subjected to aging effect are quite different from those of overconsolidated clay formed by release of the overburden. (Author/TRRL)