MECHANISM ON STRENGTH CHARACTERISTIC OF LATERITIC SPECIMENS PREPARED WITH DIFFERENT WATER CONTENTS

The compacted lateritic specimens, prepared at dry side of optimum water content(dry specimens) and wet side of optimum water content(wet specimens) in proctor, were applied suctions by axial transform technique(ATT)or vapor equilibrium technique(VET),respectively. The specimens were firstly carried out suction-controlled shear tests under constant net stress by unsaturated triaxial apparatus, to investigate the effect of specimen prepared water content on the strength characteristic of lateritic clay. The obtained results illustrate that peak strength and dilatancy of specimens increase with an increase in suction, no matter dry specimens or wet specimens. And strain-softening and shear-dilatancy in the stress-strain curves are observed in the specimens with high suctions. In addition, the dry specimen has higher peak strength and more dilatancy than that of wet specimen at the same suction, which verifies that the specimen prepared water content has great influence on the strength characteristics of compacted lateritic specimens. Then, the results obtained from the mercury intrusion porosimetry(MIP)on both dry and wet specimens, indicate that the pore size distributions(PSDs) are different for dry and wet specimens with the same void ratio and suction. The bimodal PSDs exhibits in the dry specimens, while the unimodal PSDs exhibits in the wet specimens. Besides, the dry specimen has higher peak strength than that of wet specimen with the same void ratio, which can be attributed to less cumulative volume of macro-pores(d>0.2 μm). Moreover, the peak strength of clay exponential decreases with an increase in the cumulative volume of macro-pores.