A STUDY OF THE BEHAVIOR OF SOIL AND ROCK SUBJECTED TO HIGH STRESS LEVELS.
Final rept. for Mar 63-May 64,
ILLINOIS UNIV URBANA
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An analytical and experimental investigation has been conducted to study the behavior of sand and clay under high stresses. The analytical work developed equations for the stress-strain properties of a medium composed of elastic equi-radii spheres in a face-centered cubic array. Theoretical relationships between the coefficient of earth pressure at rest, the angle of internal friction, and the coefficient of friction between the spheres were also derived. A special zero-lateral-strain device was developed for one-dimensional compression tests on sand and clay. The tests were carried to axial stresses of 3300 psi on four sands and 2200 psi on five remolded clays. The tests on sand demonstrated that the grain shape and gradation were as important as relative density in influencing the stress-strain properties. Controlled radial strain tests on the sand, with axial stresses up to 5000 psi, disclosed a failure envelope with a significant decrease in slope under the high pressures. Unloading of the sands and clays caused the coefficient of earth pressure at rest to increase and approach the coefficient of passive earth pressure. Author