Compressive Strength for an Aggregated and Partially Saturated Soil
- Mark A. Nearing
Soil strength increases with the application of soil water suctions, which impart an increasing level of effective confining stress on the soil mass. The relationship between effective confining stress and suction is influenced by soil water content. For sands, effective confining stress is approximated by the multiple of soil water suction and total saturation of the soil pores. For aggregated soils this is not true. This study was undertaken to test the hypothesis that the saturation of interaggregate pores in aggregated soils controls the level of effective stress and, subsequently, soil strength relationships. The soil used is a highly aggregated, mixed mineralogy, Paulding clay (very-fine, illitic, nonacid, mesic Typic Haplaquept) from northwestern Ohio. Unconfined compressive strength was measured for five different aggregate size groups across a range of soil water suction levels. Triaxial compression strength was measured on saturated soil samples for which effective confining stress was well defined within the triaxial test cell. Results indicated that axial stress at failure for the soil was linearly related to the product of soil water suction and the saturation level of the interaggregate soil pores. Also, the slope of the regression line was statistically equivalent to the slope of the line relating axial failure stress and effective confining stresses in the saturated triaxial tests. The experimental results support the hypothesis that interaggregate pore water controls the effective confining stress level, and hence compressive strength, for aggregated soil.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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