The Effect of End Restraint on Volume Change and Particle Breakage of Sands in Triaxial Tests

Abstract

The distributions of volume change and particle breakage within specimens were compared for uniform sands in drained triaxial tests with and without lubricated end platens. The results showed that the volume change at failure, either dilation or compression, of the sands was slightly higher for lubricated specimens at a higher failure strain than for unlubricated specimens, and the difference was proportional to the total volume change at failure. The sands exhibited insignificant differences in uniformity of volume change for specimens with and without lubricated ends under loading before the peak strength. However, a distinctly larger volume change at the middle portion of unlubricated specimens was observed after the loading reached the peak strength. Similar results were obtained for the particle breakage within the specimens in triaxial tests. End lubrication induced more uniform particle breakage of sands after the peak strength was reached. Finally, Rowe's stress-dilatancy theory was evaluated with considerations of dilatancy factor and particle breakage. Particle breakage was found very important in considering strength and volume change of sands.