A Generalized Plasticity approach for describing the behaviour of silty soils forming the Venetian lagoon basin

Tonni, Laura; Cola, Simonetta; Pastor, Manuel

doi:10.1201/9781439833766.ch13

Cited by 10 publications

(12 citation statements)

References 12 publications

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“…The laws proposed by Tonni et al . 12 and Ling and Yang 13 are worth mentioning, where H 0 is a function of void ratio. Here, we have chosen the law where H

_{′}^{0}

y β

_{′}^{0}

are additional model parameters.…”

Section: State Parameter‐based Generalized Plasticity Modelmentioning

confidence: 99%

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Generalized plasticity state parameter‐based model for saturated and unsaturated soils. Part 1: Saturated state

Manzanal¹,

Merodo

Pastor

2010

Num Anal Meth Geomechanics

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SUMMARYThe behavior of granular materials is known to depend on its loose or dense nature, which in turns depends both on density and confining pressure. Many models developed in the past require the use of different sets of constitutive parameters for the same material under different confining pressures. The purpose of this paper is to extend a basic generalized plasticity model for sands proposed by Pastor, Zienkiewicz and Chan by modifying the main ingredients of the model flow-rule, loading-unloading discriminating direction and plastic modulus-to include a dependency on the state parameter. The proposed model is tested against the available experimental data on three different sands, using for each of them a single set of material parameters, finding a reasonably good agreement between experiments and predictions.

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“…The laws proposed by Tonni et al . 12 and Ling and Yang 13 are worth mentioning, where H 0 is a function of void ratio. Here, we have chosen the law where H

_{′}^{0}

y β

_{′}^{0}

are additional model parameters.…”

Section: State Parameter‐based Generalized Plasticity Modelmentioning

confidence: 99%

“…Since then, several improvements have been proposed to describe several important features of soil behavior. Works on anisotropic soils 6, continuous plasticity 7, unsaturated soils 8, 9, degradation phenomena 10 and unified approach for sand 11–13 are worth mentioning.…”

Section: Introductionmentioning

confidence: 99%

Generalized plasticity state parameter‐based model for saturated and unsaturated soils. Part 1: Saturated state

Manzanal¹,

Merodo

Pastor

2010

Num Anal Meth Geomechanics

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“…3. Silt is the prevailing lithology of the salt-mashes located in the northern lagoon basin close to the actual littoral strips (Tonni et al, 2006;Biscontin et al, 2007;Cola et al, 2008). Mudflat deposits are composed mainly of clayey silt whereas channel units are medium to fine sand layers, often with shell fragments, interbedded by silt laminations.…”

Section: The Study Areamentioning

confidence: 99%

Characterizing marshland compressibility by an in-situ loading test: design and set-up of an experiment in the Venice Lagoon

et al. 2020

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The fate of coastal marshlands in the near future will strongly depend on their capability to maintain their elevation above a rising mean sea level. Together with the deposition of inorganic sediments during high tides, organic soil production by halophytic vegetation, and organic matter decomposition, land subsidence due to natural soil compression is a major factor controlling the actual elevation of salt-marsh platforms. Due to their high porosity and compressibility, the marsh sedimentary body undergoes large compression because of the load of overlying more recent deposits. The characterization of the geotechnical properties of these deposits is therefore of paramount importance to quantify consolidation versus accretion and relative sea level rise. However, undisturbed sampling of this loose material is extremely challenging and lab tests on in-situ collected samples are not properly representative of in-situ conditions due to the scale effects in highly heterogeneous silty soils such as those of the Venice lagoon. To overcome this limitation, an in-situ loading test was carried out in the Lazzaretto Nuovo salt-marsh in the Venice Lagoon, Italy. The load is obtained by a number of plastic tanks that are filled with seawater, reaching a cumulative load of 40 kN applied on a 2.5 × 1.8 m 2 surface. Specific instrumentations were deployed before positioning the tanks to measure soil vertical displacement at various depths below the load (0, 10, and 50 cm) and distances (0, 40, and 80 cm) from the load centre. Moreover, six pressure transducers were used to record overpressure dissipation over time. The collected datasets will be interpreted through a 3-D flow-deformation model that, once calibrated, provides reliable estimates of the compressibility values for each monitored depth interval.

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“…The Newton-Raphson iteration procedure at the local level, i.e. at each Gauss point of the finite element mesh is expressed by Equations (33) and (34). Given a previous constitutive state defined by stress tensor, total and elastic strain tensor and plastic modulus, and a total strain increment the procedure will produce an updated constitutive state.…”

Section: Drained Triaxial Test With Adige Sandmentioning

confidence: 99%

“…The extension of the original SandPZ model to take into account density and stress level dependency through the introduction of a state parameter has already been developed by several authors [33][34][35]. In unloading conditions irreversible strains are contractive.…”

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confidence: 99%

A generalized midpoint algorithm for the integration of a generalized plasticity model for sands

Mira¹,

Tonni²,

Pastor³

et al. 2008

Numerical Meth Engineering

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SUMMARYThis paper describes a method of performing the integration of generalized plasticity models, in which, unlike classical elastoplasticity, the yield surface is not explicitly defined. The algorithm is based on a generalized midpoint scheme and is applied to a specific generalized plasticity model for sands, in which a hyperelastic formulation is introduced to describe the reversible component of the soil response instead of the hypoelastic approach originally proposed. In this way, an efficient integration scheme is developed in the elastic strain space. The consistent, algorithmic tangent operator is derived. Isoerror maps are generated to study the local accuracy of the numerical integration algorithm. Results from a series of numerical examples based on the simulation of drained triaxial tests are given to illustrate the accuracy and convergence properties of the algorithm, both at the local and at the global level. Finally an example is given of the simulation of a cyclic triaxial test to illustrate the improvement on accuracy caused by the use of a hyperelastic law into the constitutive equations, as opposed to the hypoelastic formulation initially adopted in the model.

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A Generalized Plasticity approach for describing the behaviour of silty soils forming the Venetian lagoon basin

Cited by 10 publications

References 12 publications

Generalized plasticity state parameter‐based model for saturated and unsaturated soils. Part 1: Saturated state

Generalized plasticity state parameter‐based model for saturated and unsaturated soils. Part 1: Saturated state

Characterizing marshland compressibility by an in-situ loading test: design and set-up of an experiment in the Venice Lagoon

A generalized midpoint algorithm for the integration of a generalized plasticity model for sands

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