Axisymmetric Strain-Path and Stress-Path Tests on CARES-Dry Clayey Sand

Abstract

Abstract : This report documents results of laboratory tests in which the responses of remolded and undisturbed specimens of CARES-Dry clayey sand were measured under controlled strain-path and stress-path loadings. The strain-path investigation measured the response of the CARES material when subjected to: (1) two strain-path shapes (designated SP2 and SP3) with three levels of peak strain (designated A, B, and C), (2) two strain-path shapes, (3) reverse strain-path tests, (4) one strain path (SP3B) conducted at several different strain rates, and (5) one strain path (SP3B) conducted at four different levels of initial prestress. Stress-path tests were conducted to attempt to characterize the hardening response of the CARES material under several load-unload-reload cycles with each cycle extending into the compression and extension regime of stress space. Test results proved that, in all ot he strain-path tests conducted on remolded specimens, a unique stresspath was produced by following a given strain path at a single strain rate. However, because of the inherent nonhomogeneity of the undisturbed specimens, significant variability was observed in the test data. Specimens and th followed the SP3 strain path reached a point of continuing strain with little change in principal stress difference or mean normal stress; during this time the stress paths were in the proximity of the failure envelope.