Soil Moisture Conditions and their Effects on the Engineering Properties of Compacted Soils

As the properties of compacted soil conditioned for a construction work may change after the construction is completed, it is essential for a reliable design for the construction to investigate not only the strength of the compacted soil directly after compaction but also the future strength of it. In either case the strength of the soil is affected mainly by the moisture content and the dry density. For this purpose the authors studied in this paper several subjects concerning (a) qualitative moisture scales to estimate future moisture condition, (b) the effect of moisture content and dry density on the strength of compacted soil, and (c) future moisture content and future dry density of compacted soil

Mechanical Model of Particulate Material Based on Markov Process

In this paper a mechanical model for particulate materials, such as sand, is proposed to analyse their stress-strain behaviours during shear. In modelling, the motion of individual particles is assumed to be a Markov process, which is one of the well-known stochastic processes, because the irregularity of particles in both shape and volume, and the complicated fabric of particulate material are considered to prohibit the deterministic approach to the motion of individual particles in a particulate material. The strain of the particulate material is then derived by the motion of particles. It is shown that the stress-strain relationships of a particulate material derived from the proposed model compare favorably with those of Toyoura sand which are obtained from the drained compression tests and the proposed model can comprehensively evaluate the inherent anisotropy due to the fabric of particulate material, the extrinsic anisotropy due to the stress history and the non-linearity of stress-strain relationship

Dynamic Behavior of Foundations (Studies on the Failure and the Settlement of Foundations)

In this paper, studies on certain dynamic behavior concerning various kinds of foundation and a device of vibration measuring are reported in four separate sections. The first section is a theoretical research on the consolidation settlement of a clayey ground, assuming the clay constitution to be a visco-elastic body constructed of an elastic element and a Voigt element in series. Though this assumption is adopted to solve the secondary time effect, sufficient experiments to examine this assumption are still left to the future. So this report can be described chiefly as a mathematical solution of the onedimmensional consolidation of a clayey foundation due to such an oscillating load applied on the boundary as the periodical change of ground water pressure, machine vibration etc. The second section is an experimental study on the gravel layer placed on the surface of the soft ground. The purpose of this study is to get some engineering information for designing such a gravel layer. One of the most important problems of the gravel layer lies in the railroad ballast bed, which is subjected to a heavy dynamic traffic load, especially in the case of the narrow gauge. The remarkable point which is cleared by this experiments is that the modulus of the ballast bed by the dynamic load varies with the vibration amplitude and differs from that by the static load. The third section is a study on the free vibration of the foundation pile, which is an important element in earthquake-proof construction. In this section a newly devised method for numerical solution is introduced. With this method it is possible not only to calculate the eigenfrequency of the foundation pile subjected to any form of soil reaction pressure but also to solve general eigenvalue problems. Results by this method are checked with the rigorous solution and applied to the investigation of the field experiment of a reinforced concrete pile. In the experiment, the pile supports no vertical load, but the numerical solution may be developed to solve an actual foundation pile loaded with a heavy structure. The fourth section is a report on an accelerometer made on trial to measure the low frequency vibration (5-50 c. p. s.) expected on the measurement in soil. This accelerometer is made with a small cantilever of a barium titanate ceramic bar as a vibration transducer, and has many merits such as good sensitivity, flat characteristics, small volume, same unit weight with soils and cheap cost. After amplified, the excited piezoelectricity is recorded electro-optically by a galvanometer on bromide paper. With this accelerometer, the vibration displacement may be obtained by integrating the record of acceleration using a suitable integraph