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2. Pre - Engineer Research and Development Center (ERDC)
3. Structures Laboratory - (4/16/1978 - 2/22/2001)
4. Publication
5. Technical Report

Title:	Axisymmetric strain-path and stress-path tests on CARES-Dry clayey sand
Authors:	United States. Defense Nuclear Agency Akers, Stephen A.
Keywords:	Clayey sand Compression Extension Laboratory tests Remolded specimens Strain-path tests Stress-path tests Undisturbed specimens Soil testing Soil mechanics Clay soils
Publisher:	Structures Laboratory (U.S.) Engineer Research and Development Center (U.S.)
Series/Report no.:	Technical report (U.S. Army Engineer Waterways Experiment Station) ; SL-86-23.
Description:	Technical Report Abstract: This report documents the results of a laboratory test program conducted by the US Army Engineer Waterways Experiment Station (WES ) 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 designated 1T and 2T, (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. The stress-path tests were conducted (1.) to attempt to characterize the hardening response of the CARES material as either isotropic or kinematic and (2.) to measure the 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 of the strain-path tests conducted on remolded specimens, a unique stress path 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 data from those tests. Specimens that 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. With knowledge of this behavior, it was shown that the data from several tests, which followed a SP3 strain path and were conducted at different levels of prestress, would define a failure envelope. Results from the reverse strain-path tests proved that a unique strain path was not obtained by following a given stress path; in this case, one generated by SP3B. The resulting strain magnitudes were dependent upon the length of time the stress path moved along the failure envelope. The strain-rate tests showed a slight increase in peak stress difference with increasing strain rate. In the stress-path test phase, WES conducted both compression and extension tests under constant axial and constant radial stress boundary conditions with its manually controlled pressure system. The available test data were insufficient to characterize the hardening response of the CARES material as either isotropic or kinematic. Several load-unload-reload tests were successfully conducted; the information gained from these tests was used for constitutive model fitting.
Rights:	Approved for public release; distribution is unlimited.
URI:	http://hdl.handle.net/11681/11240
Appears in Collections:	Technical Report