Some Factors Affecting Cyclic Undrained Triaxial Strength of Sand

Abstract

ABSTRACT A series of cyclic undrained triaxial tests was performed to evaluate the effects of several factors on the cyclic undrained behavior of Toyoura Sand. This study was performed in parallel with a cooperative test program (Toki et al., 1986) where at five laboratories similar tests were performed following the same specified tes tprocedure. It was found by the present study that the cyclic undrained triaxial strength of air-pluviated loose and dense Toyoura Sand is rather insensitive to the change in (1) the loading frequency between 0.05 Hz and 1. 0 Hz, (2) the height to diameter ratio H/D between 1.5 and 2.7 for non-lubricated ends, (3) the sustained compression period between 6 minutes and 16 hours and (4) the degree of end restraint for H/D = 2.0 and 2. 4, whereas the strength is affected by the change in (1) the method of pluviating sand through air when specimens are loose, (2) the speciman diameter and (3) the deviation from the isotropic stress condition during compressing the specimen. It is also suggested to evaluate the effects of various kinds of system compliance in such a unified form as shown in the paper. It is concluded that unaccountable and subjective scattering in the cyclic undrained triaxial strength data can be reduced to a small value without large difficulties by controlling the factors which influence the data, whereas the effects of system compliance on the measured strength should be taken into account appropriately even for fine sands as Toyoura Sand.