Effect of suction on unconfined compressive strength in partly saturated soils

Unconfined compression tests are performed in this study to evaluate the effect of matric suction on the strength and the deformation characteristics of dynamically and statically compacted silt soils. In order to estimate the suction stress, the change in suction and the volume change of the soil samples are measured, and the relationship between suction stress and unconfined strength is established. Under different conditions of the initial degree of saturation and the dry density in soils, the relationship between suction and the degree of saturation at failure can be expressed by a unique soil-water characteristic curve. This result shows a similar tendency to that of a predicted equation using the same parameters for the soil-water characteristic curves. The unconfined compressive strength is also affected by the suction stress which seems to work as a confining pressure for unsaturated conditions. These results demonstrate that the suction stress can be used for estimating the relationship between suction and the unconfined compression test.