Effect of Soil Suction On Shear Strength and Resilient Modulus of Subgrade Soils.

Pavements are constructed on compacted soils that are typically unsaturated. The negative pore-water pressure (soil suction) is due to the ingress of water into soil particle interstices and having a significant effect on pavement foundation stiffness and strength. This study characterized the effects of soil suction on shear strength and resilient modulus of four soils representing different regions of Minnesota. The deviator stress generated from shear strength measurements followed a power function relationship with soil suction. Resilient modulus also followed the power function relationship with suction but these relationships fell within a narrow range. Presented are models for incorporating suction effects in shear strength and resilient modulus measurements of highly compacted subsurface soils.