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The influence of non-plastic fines on undrained monotonic behaviour of sand was investigated over a wide range of fines content (FC = 0–40%), global void ratio and initial mean effective stress ( p 0 ′ = 100 kPa to 500 kPa), by performing triaxial compression tests with isotropic and anisotropic consolidation. For the sand–silt mixtures, steady-state line in the e − log(p′) space was found to be dependent on fines content with the existence of a limiting fines content, which defines the transition from a "fines in sand" to a "sand in fines" soil fabric. It is demonstrated that by means of the concept of equivalent granular void ratio, e*, all steady-state/critical state data points can be well described by a unique relationship in the e* − log(p′) space called the equivalent steady-state line (EG-SSL), regardless of fines content. The equivalent granular state parameter (ψ*), defined in terms of e*, and the EG-SSL can be effectively adopted for predicting the undrained monotonic behaviour of sand–silt mixtures and the onset of static instability, irrespective of fines content and initial state of the sand–silt mixtures. [ABSTRACT FROM AUTHOR]

The paper presents a dynamic finite-element analysis of the deformation of saturated cohesionless soil in the vicinity of the toe of a vibrating cylindrical pile. The soil behaviour is described by a hypoplastic constitutive model with intergranular strain assuming locally undrained conditions for the pore fluid. Emphasis is placed on the detailed analysis of stresses and displacements in the soil. It is shown that, starting from a homogeneous stress state, the first several cycles of vibration lead to the formation of a permanent liquefaction zone with vanishing effective stresses at a certain distance from the pile. The displacement field reveals an accumulation of residual displacements in the soil in the form of rotation. The influence of the initial stress state, the pore fluid compressibility, the pile displacement amplitude and the soil density on the formation of a liquefaction zone, on the stress amplitude in the soil and on the intensity of the permanent rotation is investigated. [ABSTRACT FROM AUTHOR]

Although the hypoplastic models for sands have exhibited good predictive capability in monotonic loading, they are not able to reproduce memory effects and predict excessive plastic accumulation under cyclic loading. To overcome these issues, a loading surface has been incorporated into a hypoplastic model. This surface is capped and has two hardening variables. Notions from the bounding surface plasticity were borrowed in order to formulate the hardening functions. With this novel model, some salient features can be described: the model can account for the accumulation of plastic deformation, a memory effect is provided by the new surface, and stress-induced anisotropy effects observed in sands are successfully simulated. A short calibration guide of the parameters is given, and some simulations for Hostun RF loose sand and Toyoura sand are presented. [ABSTRACT FROM AUTHOR]

Shear banding represents a local failure mechanism of a soil structure as a response to shear loading. In soil structures of different spatial scales systems of regularly spaced shear bands can be observed as a consequence of extensional loading. The phenomenon of single shear bands, defined as thin zones of localized deformation with a discontinuity of the strain field at its boundaries, is well understood. Inside the shear band the material undergoes inelastic strain softening accompanied by shearing and dilation, whereas the material outside the shear band unloads accompanied by elastic contraction in extension tests. Despite numerous experimental and numerical investigations, the physical mechanisms and parameters determining the spacing of parallel shear bands remained unknown. The paper in hand presents an analytical solution for the spacing of the shear bands and a comparison with a large base of experimental data gained from 1 g and ng (geotechnical centrifuge) model experiments. The analytical solution is based on the assumption that the elastic energy rate in the unloaded zone between the shear bands tends to a minimum value. The spacing was calculated as the energetically preferred solution for a broad range of cohesive-frictional granular materials. The dependency of the calculated spacing on initial and boundary conditions as well as on material parameters was found to be in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

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Copyright of Archive of Applied Mechanics is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)