砂と粘土のせん断特性の類似性とそのメカニズムについて

Abstract

Sand is an assembly of particles, therefore its mechanical proparties should reflect the micro-scopic behavior of the individual particles. It is also seen that clays, which consist of very fineparticles, show a granular property such as dilatancy. The granular nature of soil is considered tobe one of its most essential properties. Therefore, in this investigation, the shearing mechanism ofgranular soil such as sand and gravel have been studied from the microscopic point of view inorder to understand its macroscopic behavior better.For this purpose, the shearing tests were carried out using not only real soils but also horizontalpiles of alminium rods and rods made of a photoelastic material with various diameters in order tosimulate a two-dimensional granular mass. From these experiments, the slope angle of particlecontact surface C, the interparticle force f and the frictional angle between the particles 3 werechosen as the fundamental factors that control the shearing resistance of soils. The concept of "thefrequency distribution of θ" was introduced in order to represent the macroscopic shearing resist-ance and dilatancy.In this paper, the stress ratio (τ/σN) and strain-increment ratio (dεN/dγ) relation is derivedfrom these microscopic considerations as follows;and it is found that this relation is applicable not only to sands but also to clays. From these ex-perimental results the similarity of the shearing mechanism between sands and clays is shown.Furthermore it is made clear that this stress ratio and strain-increment ratio relation is related tothe stress dilatancy theory of P. W. Rowe.