THE STRENGTH AND DEFORMATION PROPERTIES OF COARSE-GRAINED MATERIALS FROM CYCLIC AND MONOTONIC LOADING TRIAXIAL COMPRESSION TESTS UNDER VARIOUS CONDITIONS

Abstract

To analyse the seismic behaviour of a fill dam that was actually damaged during a recent earthquake, a series of triaxial tests were performed on gravel including fines retrieved from the site. To understand different performances of the downstream and upstream slopes of the rock shell, saturated specimens were subjected to monotonic and cyclic loading histories under undrained conditions, while specimens that were moist as in the field under drained conditions. With undrained saturated specimens and drained moist specimens, the effects of cyclic loading conditions on the peak strength when subsequently subjected to monotonic loading were evaluated. In all the test conditions, the effects of compacted dry density on the strength and deformation properties were evaluated. The following was found. The residual strain by cyclic loading is much larger with the undrained saturated specimens than with the drained moist specimens. The increase in the strength with an increase in the compacted dry density is significant in both cases. The effects of cyclic loading on the subsequent compressive strength are negligible with drained moist specimens, while the strength may decrease significantly by cyclic loading with undrained saturated loose specimens.