Experimental investigation on the stress-dilatancy response of aggregate-geogrid interface using parameterized shapes

Abstract

In resisting and distributing applied loads of reinforced soil structures, the interface interaction between soil particle and geogrid is influenced by the particle shape. The direct shear tests were carried out in this paper to demonstrate that varying the particle shape alters the geosynthetic-soil interface shear response under different normal stresses (σn) and geogrid apertures (Ag). Crushed limestone (CS) with an 8-mm particle size (D) was mixed with different uniform spherical granular (SG) medium percentages (0%, 25%, 50%, 75% and 100%) to attain samples with different particle shapes, which was described and quantified in terms of the overall regularity. The test results revealed that all samples exhibited shear softening during shearing, and the residual factor characterized the post peak displacement softening behavior. Moreover, the interface shear strength, shear contraction and dilation, and interface peak and residual friction angles decreased with increasing overall regularity. An equation was proposed to estimate the stress-dilatancy response for different particle shapes. For the different geogrid apertures, the maximum shear stress ratio Ag/D was 3.75 at an overall regularity between 0.707 and 0.774, while the other Ag/D values were 4.375. The observation obtained are expected to provide better understanding of soil-geogrid interaction using parameterized shapes.