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Fem validation of a double porosity elastic model for consolidation of structurally complex clayey soils
No full textLaboratory consolidation of structured clayey soils is analysed in this paper. The research is carried out by two different methods. The first one treats the soil as an isotropic homogeneous equivalent Double Porosity (DP) medium. The second method rests on the extensive application of the Finite Element Method (FEM) to combinations of different soils, composing 2D or fully 3D ordered structured media that schematically discretize the complex material. Two reference problems, representing typical situations of 1D laboratory consolidation of structured soils, are considered. For each problem, solution is obtained through integration of the equations governing the consolidation of the DP medium as well as via FEM applied to the ordered schemes composed of different materials. The presence of conventional experimental devices to ensure the drainage of the sample is taken into account through appropriate boundary conditions. Comparison of FEM results with theoretical results clearly points out the ability of the DP model to represent consolidation processes of structurally complex soils. Limits of applicability of the DP model may arise when the rate of fluid exchange between the two porous systems is represented through oversimplified relations. Results of computations, obtained having assigned reasonable values to the meso-structural and to the experimental apparatus parameters, point out that a partially efficient drainage apparatus strongly influences the distribution along the sample and the time evolution of the interstitial water pressure acting in both systems of pores. Data of consolidation tests in a Rowe's cell on samples of artificially fissured clays reported in the literature are compared with the analytical and numerical results showing a significant agreement. Copyright (C) 2000 John Wiley and Sons, Ltd
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An analysis of strong discontinuities in a saturated poro-plastic solid
Full text linkWe present in this paper an analysis of strong discontinuities in fully saturated porous media in the infinitesimal range. In particular, we describe the incorporation of the local effects of surfaces of discontinuity in the displacement field, and thus the singular distributions of the associated strains, from a local constitutive level to the large-scale problem characterizing the quasi-static equilibrium of the solid. The characterization of the flow of the fluid through the porous space is accomplished in this context by means of a localized (singular) distribution of the fluid content, that is, involving a regular fluid mass distribution per unit volume and a fluid mass per unit area of the discontinuity surfaces in the small scale of the material. This framework is shown to be consistent with a local continuum model of coupled poro-plasticity, with the localized fluid content arising from the dilatancy associated with the strong discontinuities. More generally, complete stress-displacement-fluid content relations are obtained along the discontinuities, thus identifying the localized dissipative mechanisms characteristic of localized failures of porous materials. The proposed framework also involves the coupled equation of conservation of fluid mass and seepage through the porous solid via Darcy's law, and considers a continuous pressure field with discontinuous gradients, thus leading to discontinuous fluid flow vectors across the strong discontinuities. All these developments are then examined in detail for the model problem of a saturated shear layer of a dilatant material. Enhanced finite element methods are developed in this framework for this particular problem. The finite elements accommodate the different localized fields described above at the element level. Several representative numerical simulations are presented illustrating the performance of the proposed numerical methods
Editorial for the Special Issue: Innovative numerical methods for soil internal erosion processes
No full textIn today’s society, with environmental loads acting with unexpected great magnitude and increasingly populated areas, earth structures for water containment and water defence must be designed and monitored with utmost care, to reduce the risk where the exposure increases [Jongman et al., 2012]. Soil internal erosion is regarded to as one of the major causes of earth embankment and dam failures, leading in the past to high death toll and economic losses [Foster et al., 2000; Richards and Reddy, 2007]. Moreover, internal erosion poses a threat of broader impact to the natural and built environment, as it may lead to slope failure, soil subsidence and structure damages, and it is of concern also in industrial engineering problems such as the sand production in oil wells [Climent et al., 2014; Fox and Wilson, 2010; Gao et al., 2022; Sterpi, 2003; Vardoulakis et al., 1996; Zhang et al., 2020].
Since its establishment in 1993, the European Working Group on Internal Erosion of Dams, Dikes and Levees, and their Foundations (EWG-IE) represents a community committed to share their interest and knowledge in soil internal erosion related matters. The Group organizes Annual Meetings, the last three being held in 2018 in Milano, Italy [Bonelli et al, 2018], in 2019 in Vancouver, Canada [Fannin, 2019], and in 2022 in Sheffield, UK [Bowman, 2022].
To maintain a link among the EWG-IE members during the Covid-19 pandemic, between 2020 and 2021 online workshops on diverse topics were organized by local groups. Given the interest raised at the workshop on “Innovative numerical methods for soil internal erosion processes”, the local organizers decided to open a call to the entire scientific community and to serve as guest editors of a themed issue on the journal Geomechanics for Energy and The Environment.
The valuable contents of the submissions, that bring up a well-balanced mix of topics involving the soil internal erosion, reflect that the call reached a broadly interested and lively community of researchers. This editorial aims at outlining the relevant key points of these contributions and placing them in the context of the state of the art
Representativeness of a double porosity model for the consolidation appraisal of highly fissured clayey soils
No full textLocalization Analysis in Dilatant Elasto-Plastic Solids by a Strong-Discontinuity Method
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mixed isogeometric collocation methods for the simulation of poromechanics problems in 1D
No full textIsogeometric collocation is for the first time considered as a simulation tool for fluid-saturated porous media. Accordingly, with a focus on one-dimensional problems, a mixed collocation approach is proposed and tested in demanding situations, on both quasi-static and dynamic benchmarks. The developed method is proven to be very effective in terms of both stability and accuracy. In fact, the peculiar properties of the spline shape functions typical of isogeometric methods, along with the ease of implementation and low computational cost guaranteed by the collocation framework, make the proposed approach very attractive as a viable alternative to Galerkin-based approaches classically adopted in computational poromechanics
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