Strength and deformation characteristics of degradable granular soils

Economical constraints and growing infrastructure developments in hilly areas accentuate the use of weak rockfill material. These soils disintegrate with time due to physical and chemical weathering. The objective of this research was to elucidate the possible mechanisms responsible for negative aging of such granular soils and its effects on their geotechnical behavior. The engineering properties of crushed soft rocks from Japan and Pakistan were investigated through a series of consolidated drained monotonic and cyclic torsional shear tests, under both saturated and dry conditions. Tests under dry conditions represented the response of intact grains, whereas saturated conditions simulated the potential reduction in strength and stiffness due to water-induced decomposition. A degradation index based on the particle size distribution of the materials before and after the each test was used to quantify the degree of deterioration. The results under dry and saturated conditions were compared and the correlation of degradation index with strength and deformation characteristics of test materials were explored. The degradation index can be used to assess the loss of strength and stiffness of granular soils due to water-induced disintegration of grains with time, quickly in the field.