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Consolidation parameters such as volume compressibility, mv, and permeability, k, of very soft slurry clay are difficult to obtain from a conventional oedometer test. A selfweight consolidation test in a centrifuge is available as an alternative test. The mv value is calculated from the f-log p relationship which is obtained from a correlation between volume ratio f and effective overburden pressure along the specimen depth after self-weight consolidation, and k is obtained from the initial settlement rate of a singly drained selfweight consolidation test. Some examples of determination of these parameters are shown for four highly plastic clays. The effect of particle segregation on these parameters in a high centrifugal acceleration field is also discussed.

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Mikasa's advanced consolidation theory and Mikasa's method of determining cv from the oedometer test are discussed. The latter consists of a curve rule method and correction of cv by primary consolidation ratio, r. Theoretical time-consolidation relationships are shown for the cases of finite strain both with and without cv change as the relation between time factor, Tv, and degree of consolidation in terms of settlement, Us. Examples on a clay and a peat show that the standard procedure of cv determination using the curve rule method and correction by r gives practically the same f-cv relationship as does the procedure based on the advanced consolidation theory, though a better curve fitting is always obtained by the latter. Advanced consolidation theory, however, is necessary to interpret the physical meaning of consolidation test results and also to make a settlement prediction in the field.

A newly designed independent principal stress control apparatus is presented together with some typical test results obtained by the apparatus. The minor principal stress on a cuboidal specimen, σx, is loaded by air pressure in the triaxial cell, and two couples of rigid platens are used to load the major and intermediate principal stresses, σz and σy. This apparatus has the following features: 1. The axial stress, σz, is applied from the underside of the specimen, the reaction being supported by a frame in the cell. It makes both the anisotropic consolidation and extension test possible; it also makes the preparation of sand or soft clay specimens very easy. 2. A new device to load intermediate stress, σy, was developed to minimize the friction between lateral loading platens and the specimen. 3. A new system to measure the specimen deformation is also developed with a no-contact gap sensor which moves up and down during the test. It can measure the total volume change and also the change of the shape of the specimen. Some typical results of triaxial test, plane strain test, and independent stress control test on two sands are presented. Deformation or distribution of strain of the specimen observed by no-contact gap sensor is also discussed.