Research Scientist, The Ohio State University, Columbus, OH
Geotechnical Engineer, Fugro-McClelland Marine Geosciences, Inc., Houston, TX
Graduate Research Associate, The Ohio State University, Columbus, OH
Associate Professor, The Ohio State University, Columbus, OH
Pages: 15 Published: Jan 2003
High positive pore pressures in subgrade soils can be expected to contribute to reduction in soil strength and stiffness. Measurement of elevated pore water pressures in the subgrades of instrumented sections of Specific Pavement Studies conducted in Ohio over the past several years have raised concerns about the long-term stability of these test sections. The objective of this study was to identify the effects of moisture content and pore water pressure on the resilient modulus (Mr) of unsaturated and saturated cohesive soils. Test results conducted on unsaturated cohesive soils at three different moisture contents (optimum, 2 to 4% dry of optimum, and 1 1/2 to 3% wet of optimum) showed that the resilient modulus and the effect of confining stress decreased with increasing moisture content. Laboratory tests on fully saturated cohesive soils showed that the resilient modulus of saturated soils decreased to less than half that of soil specimens tested at optimum moisture content. Residual pore water pressure increased with an increase in the deviator stress, and a decrease in the loading period. The time to dissipate residual pore water pressure, which was large in comparison to the load rate, increased with increasing deviator stress. The resilient modulus of fully saturated cohesive soil was much less under faster (1 second per cycle) cyclic loading than slower (8 seconds per cycle) cyclic loading.
cohesive soil, loading period, moisture content, pore water pressure, resilient modulus, residual, saturated, subgrade, unsaturated
Paper ID: STP12523S