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Influence of particle angularity on the suffusion in gap-graded granular soils remains unclear up to now. In this study, systematical numerical simulations that consider the particle shape as quasi-spherical polyhedra in different angularity are performed with the coupled discrete element method (DEM) and the computational fluid dynamics (CFD) approach. The suffusion of six gap-graded soil samples with 25% fines content is examined by imposing an upward seepage flow. Conventional triaxial tests are also conducted on the pre-eroded and post-eroded specimens to study the coupling influence of angularity and suffusion on the mechanical characteristics of granular soils. Fines loss, vertical displacement, soil strength, volume flow rate, microstructural analyses of force networks, the cumulative percentage of contact force, and the anisotropy of contact are investigated. Results turn out that the angularity intensifies the internal erosion resistance as the fines loss decreases significantly with the increasing angularity. The soil peak strength and friction angle are approximately linearly correlated with angularity. Erosion-induced particle redistribution reduces the degree of anisotropy of contact normal and contact normal force. This study may improve our understanding of the effect of particle angularity on suffusion with both microscopic and macroscopic evidence. [ABSTRACT FROM AUTHOR]

This paper establishes a semi-analytical lower-bound dynamic shakedown method to investigate the shakedown of the pavement on saturated subgrade based on dynamic Biot's consolidation theory, considering a rolling-sliding contact between vehicle tire and pavement. This analysis has demonstrated that properties of the saturated subgrade generally have negative effects on the shakedown limit of the pavement system under high-speed traffic loadings. In general, the classical single-phased shakedown theorem overestimates the shakedown limit of the pavement on the soft ground of low permeability, particularly under high-speed traffic loadings. The shakedown limit of the pavement on a saturated subgrade gradually reduces with decreasing permeability of the subgrade. The sliding-induced friction significantly affects the shakedown limit and the location of critical shakedown failure. The permeability of the saturated subgrade has considerable effects on the shakedown limit for the case of low tire-pavement friction. The shakedown limit of the pavement on a saturated subgrade and a single-phased subgrade shows a considerable difference at the optimum modulus ratio, at which the critical shakedown failure tends to shift from the saturated subgrade to the pavement layer. The proposed method will be more desirable to evaluate the performance of the pavement in the saturated soft ground. [ABSTRACT FROM AUTHOR]