This paper deals with the one-dimensional volume change behaviour of kaolinite, montmorillonite and black cotton soil, when soaked in the partly saturated state. These clays were compacted in a partly saturated state to different densities with different initial moisture contents in oedometer rings loaded to different pressures ranging from 0.0625 to 8.0 tons/sq. ft and then soaked with distilled water at these pressures. Further, consolidation was then carried out on these soaked samples, in the conventional manner. The results were analysed in the light of the modified effective stress concept together with the physical mechanisms involved.The results obtained clearly indicate that the volume change behaviour of these clays during soaking is controlled basically by two mechanisms which are governed by the modified effective stress concept which takes into consideration the electrical attractive and repulsive forces at particle level. In Mechanism I, the volume change behaviour is controlled by the shearing resistance at interparticle level and in Mechanism II, by the long range electrical repulsive forces. Although these effects operate simultaneously, Mechanism I primarily controls non-expanding clays like kaolinite, and Mechanism II the expanding lattice type of clays like montmorillonite.

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To design the machine foundation for vertical vibrations, the resonant frequency, f_n, and peak amplitude, A_max, of the machine foundation-soil system have to be determined to avoid resonance condition. Sung has worked out analytical solutions and readily usable curves for three probable types of contact pressure distribution to predict the above. However, it has been found that the prediction of machine foundation response is not possible from a single field vibration test using the existing solutions in as much as the contact pressure distributions along with the corresponding μ and G values obtained from a single field vibration test are only intermediate tools for the prediction of machine foundation response. In this paper, analytical solutions, their numerical evaluations and corresponding usable curves for Annular ring-Uniform loading contact pressure distribution are presented. It is found that the newly worked out solutions are satisfactory and they increase the probability of prediction of machine foundation response from a single field vibration test.

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A description is given of a series of full scale field tests in which air and water were injected into a deposit of laminated silt via a well system. The results of the tests are compared and it is shown that the pressure and head profiles resulting from air and water flow can both accurately be predicted by applying Fick's diffusion law.

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Shirasu in southern Kyushu is the deposits caused by volcanic activities, and structurally unstable. It is also called "special soil". This paper contains the descriptions on the formation and constituents of Shirasu, the engineering classification, and the physical and mechanical properties, for estimating the stability of slopes in undisturbed Shirasu and compacted earth fills.Shirasu possesses grains of peculiar shape and surface texture, and its chemical components are composed dominantly of silica and alumina. As for mineral composition volcanic glass greatly surpasses others in quantity. Shirasu deposits can be classified into five distinct groups from the standpoint of soil engineering with its geological aspects in consideration. Physical and mechanical properties are different with the kinds of Shirasu due to engineering classification. Research is needed in order to develop the specification of designs of structures in and of Shirasu and to prevent and decrease in disaster.

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The stabilization characteristics of the vibratory sand compaction pile method, popularly being adopted in Japan for stabilization of soft soil, as applied to cohesionless subsoils, have been examined in the aspect of its practical applications. Referring to numerous examples of standard penetration tests carried out before and after treatment to check the stabilization effect in the field, the influences of five factors related to cohesionless subsoil compaction, depth from ground level, sand/gravel content, N-value of original ground, sand pile area ratio and vibrator size, on the N-value of treated ground have been investigated.

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