RELATION BETWEEN RESILIENT MODULUS AND STRESS CONDITIONS FOR COHESIVE SUBGRADE SOILS

The relation between stress conditions and resilient modulus, which is a necessary input parameter in fatigue design of asphalt concrete pavements is established. For a cohesive subgrade soil there is a relation between resilient modulus and deviator stress, confining pressure, and matrix suction. A proposed constitutive relation was experimentally checked by using samples of compacted glacial till from the Qu'Appelle Moraine in Saskatchewan, Canada. Four series of repeated triaxial tests were performed on the repeated-load triaxial system developed at the University of Saskatchewan. Matrix suctions were measrured on a pressure-plate device immediately after each repeated-load test. Experimental data indicate a good correlation between the resilient modulus and the stress variables. The stress variables of most significance with respect to changes in resilient modulus are deviator stress and matrix suction. An equation is proposed by which the resilient modulus of a compacted subgrade soil can be linked to these stress variables. /Author/