STUDY OF THE DYNAMIC STRESS-STRAIN AND WAVE-PROPAGATION CHARACTERISTICS OF SOILS; REPORT 2, CORRELATION OF STRESS-STRAIN AND WAVE-PROPAGATION PARAMETERS IN SHOCK-LOADING DRY SANDS
UNITED RESEARCH SERVICES CORP BURLINGAME CA
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Wave propagation studies conducted on laterally confined columns of three granular materials which exhibit nonlinear stress-strain behavior are described. Under these conditions, axial and lateral stresses and strains, wave velocities, and particle velocities measured at points along the column are reported. A new technique for measuring free-field displacements without physically contacting the soil is also described. A correlation between the moduli computed from the stress wave velocity, particle velocity, and the secant drawn to the stress-strain curve is presented. Relationships between stress, strain, wave velocity, and particle velocity are shown to be such that if any two of the parameters are known, the other two may be determined. Comparison of the data is made with the Hertzian theory relating confining stress to wave velocity or constrained modulus. Several interesting though preliminary observations on stress precursors resulting from initial axial stresses are presented. Based on these observations, an explanation is presented for the disparity between moduli based on constrained compression tests and those back- figured from seismic velocities.