Effects of Dilatancy and Particle Size Observed in Model Tests on Sand

Centrifuge Modeling of Granular Soil Response Over Active Circular Trapdoors

“…Although the shear band formed a similar narrow chimney when it touched the surface, the chimney size was not expanded compared to that in the 1 g test in the last stage. A similar bulging localization was observed The dominant factor controlling the direction in which localization can develop is the kinematic constraint associated with the angle of dilation mobilized within the localization (Stone and Wood, 1992). It is known that increasing the stress level tends to reduce the angle of dilation (Bolton, 1986).…”

Centrifuge model test on the face stability of shallow tunnel

“…Furthermore, grain size effects have been detected on the development of shear band patterns in a trap door test simulating chimney collapse [22,24,34]. While collapse load is not sensitive to the grain size, the propagation of a collapsing chimney is sensitive to B/d 50 , even for a ratio as large as 1,000, which cannot be modeled at small scale [13,28,39]. For these reasons, a small-scale model behaves stiffer than its prototype.…”

Discussion: Uplift resistance of buried submarine pipelines: comparison between centrifuge modelling and full-scale tests

“…10 (Stone & Wood, 1992). It is apparent from these tests that the relative displacement across the shear box (and hence across the shear band), which coincides with the peak and critical state friction angles, appears to be a function of the grain size.…”

“…This discussion concerns the scale effects reported by the authors, and is intended to confirm the hypothesis that any inconsistency in the conventional understanding of centrifuge tests is the result of the dependence of the mobilised shear stress across localisations (or shear bands) on the relative displacement across the localisation. It has been previously proposed (Scarpelli & Wood, 1982;Muhlhaus & Vardoulakis, 1987;Stone & Wood, 1992) that this relative displacement is primarily a function of the soil grading (characterised by the mean particle size, d 50 ), and thus for small-scale modelling of problems involving discontinuous soil mechanics, it may be necessary to scale the particle size (or, more correctly, the grading curve) to ensure that: (a) the kinematics of the reduced scale model are compatible with those of the corresponding prototype; (b) the scale of the localisations themselves does not adversely affect the model response; and (c) the mobilised strength on localisations in the model is compatible with that which would be present in the corresponding prototype.…”