| In the last few years, cyclic simple shear testing has been analyzed experimentally and theoretically and the advantages and limitations of the test presented. The main drawback concerns the sample size, in that for a small sized sample, the test results are affected by the nonuniformity of the stress in the sample.;From both the experimental and the theoretical study, a statistical models correlating the shear modulus and damping values with the sample size were developed and the ideal size for a sample to be tested in cyclic simple shear apparatus was defined. In addition, correction factors for the data obtained in simple shear testing were developed to be used if the sample size differed from the ideal size.;A comprehensive experimental program to investigate the sample size effect on the primary dynamic soil properties, namely the shear modulus and damping, was undertaken. The sample sizes used varied in diameter from three to twelve inches and in height from one fourth inch to four inches. Thus a wide range of diameter to height ratios were investigated. The soil tested was Ottawa Sand and the samples for all testing were prepared by air pluviation. Other variables studied in addition to the sample size were the shear strain amplitude, the number of cycles, the relative density and the vertical applied pressure. In all tests the sinusiodal shear strain was applied and controlled by an electro-hydraulic closed loop system. In addition, a linearly elastic finite element analysis was performed on samples of the same size as those tested experimentally, to augment the experimental results. |
