砂の変形特性について

Abstract

This paper is a report of some experimental researches and their discussion on therelations between stress, strain and volumetric change with Toyoura standard sand undervarious stress condition in triaxial apparatus. Stress condition are as follows; (1) meanprincipal stress a~m is kept constant (a-rn-constant test). (2) isotropic compression test, (3)allround pressure 6~3 is kept constant (a-3-constant test), (4) deviator stress (a-1 a-3) is keptconstant ((a-1 -a-3)-constant test), (5) repetitional deviatoric stress is applied, Result fromthese tests following conclusions are summerized, (1) In a-rn-constant test, if void ratio of sand is same, its stress-strain curve chieflydepends on (a-1-a-3)/a-m (Fig. 3).(2) In a-rn-constant test, relation between volumetric change A V/V and shearing strain~represented by straight line on the logarithimic paper (Fig. 7, Fig. 8).(3) In isotropic compression test, relation between volumetric change A Vi V and isotropicpressure a- is not always linear on logarithmic paper as proposed by Wilson & Suttonand Jakobson (Fig. 10, Fig. 11).(4) Instead of the second term of Eq. (3), which represents the dilatancy effect of sand, the following term is proposed.D*(_a-1a-3) (where D* coefficient)(5) It is obsarved in repetitional loading test that the effect of repetitional stress appearsmore remarkable if deviator stress (a-1-a-3) becomes larger as shown Fig. 18 (a).