Numerical analysis of wetting‐induced instabilities in partially saturated soils under plane strain conditions

Rotisciani, G. M.; Desideri, Augusto; Prisco, Claudio di

doi:10.1002/nag.2939

Cited by 6 publications

(6 citation statements)

References 35 publications

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“…The pile response is studied by means of three-dimensional coupled analyses via the finite element code Abaqus/Standard. The constitutive soil model is implemented in a user-defined subroutine [35,36]. The hydro-mechanical behaviour of the kaolin is described with the Modified Cam Clay Model extended to unsaturated conditions and the modified Gardner SWRC previously introduced.…”

Section: Numerical Modelmentioning

confidence: 99%

A Numerical Model to Study the Response of Piles under Lateral Loading in Unsaturated Soils

et al. 2021

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The interaction between a laterally loaded pile and the surrounding soil is typically limited to the shallower soil layer. Often, this zone is above the water table and therefore the interaction takes place under unsaturated conditions. The available evidence is scarce but suggests that unsaturated conditions play a major role on the pile’s response. The actual mechanisms governing the soil–pile interaction under unsaturated soil conditions are not understood entirely, and this paper provides a useful insight on this topic. The analysis is carried out with a fully coupled three-dimensional numerical model, the soil behaviour is simulated with a Modified Cam Clay Model extended to unsaturated conditions. The model accounts for the increase in stiffness and strength of unsaturated soils as well as the volumetric collapse upon wetting. The constitutive model is calibrated on the laboratory data and validated against centrifuge data with satisfying agreement. The results highlight the substantial differences in the soil reaction against the pile depending on different water saturation profiles. The study also shows that the influence of unsaturated conditions on the pile response increases as the pile’s flexibility increases. Comparing the findings with currently available design methods such as the p–y curves, it is found that these do not adequately describe the unsaturated soil reaction against the pile, which opens the door for new research in the field. The proposed numerical model is a promising tool to further investigate the mechanisms underlying the soil–pile interaction under unsaturated soils.

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Section: Numerical Modelmentioning

confidence: 99%

A Numerical Model to Study the Response of Piles under Lateral Loading in Unsaturated Soils

et al. 2021

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“…In the proposed element test simulations, particular emphasis is placed on the failure conditions, with the aim of investigating the stability of the material by detecting the, so-called, loss of controllability domain. In fact, here we interpret the occurrence of actual or potential instabilities by means of the controllability theory, originally proposed by Nova [43] and then extended in Buscarnera and di Prisco [15], along the line of what discussed in Buscarnera and Nova [11,14], Buscarnera [11], Marinelli and Buscarnera [40], Buscarnera and Dattola [12] and in Rotisciani et al [52]. Moreover, simple analytical criteria for capturing soil instabilities are proposed and validated against numerical results.…”

Section: Introductionmentioning

confidence: 78%

Unsaturated structured soils: constitutive modelling and stability analyses

2021

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The paper presents a new single-surface elasto-plastic model for unsaturated cemented soils, formulated within the critical state soil mechanics framework, which should be considered as an extension to unsaturated conditions of a recently proposed constitutive law for saturated structured soils. The model has been developed with the main purpose of inspecting the mechanical instabilities induced in natural soils by bond degradation resulting from the accumulation of plastic strains and/or the changes in pore saturation. At this scope, the constitutive equations are used to simulate typical geotechnical testing conditions, whose results are then analysed in light of the controllability theory. The results of triaxial tests on an ideal fully saturated cemented soil and on the corresponding unsaturated uncemented one are first discussed, aiming at detecting the evidence of potentially unstable conditions throughout the numerical simulations. This is followed by similar analyses considering the combined effects of both the above features. For each analysed case, a simple analytical stability criterion is proposed and validated against the numerical results, generalizing the results, and highlighting the crucial role of state variables and model parameters on the possible occurrence of failure conditions.

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“…The similarities observed in the curves (u w , e w ) and ( v , e w ) stem from the mutual interaction between the two response variables. The S r increase due to the imposed water inflow and the consequent suction removal cause skeletal deformations that, in turn, affect the current values of suction and saturation degree ( [5]). The wetting process becomes unstable when the soil cannot sustain anymore the applied loading.…”

Section: Type Valuementioning

confidence: 99%

“…These instabilities are due to the reduction of matrix suction and, thus, shear strength resulting from water infiltration [1][2]. Additional hydraulically induced instabilities can occur before attaining shear failures for positive values of the hardening modulus [3][4][5]. These instabilities manifest as sudden and significant collapses of the solid skeleton accompanied by uncontrolled growth of pore water pressures and soil saturation.…”

Section: Introductionmentioning

confidence: 99%

Wetting-induced instabilities: triggering mechanism and predisposing factors

2023

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This paper addresses the topic of unsaturated soil stability focusing on wetting-induced instability mechanisms occurring before the attainment of the classical shear failure. The study was conducted by simulating a series of imbibition tests on elementary soil volumes by controlling water contentand net stresses. The behaviour of an ideal coarse-grained soil was described by combining the WR2-Unsat model for the solid skeleton and the Van Genuchten relationship for the definition of the water retention curve. The model reproduces the soil response upon wetting, modelling the activation mechanism of the volumetric instability and identifying the factors that most contribute to its triggering.

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Numerical analysis of wetting‐induced instabilities in partially saturated soils under plane strain conditions

Cited by 6 publications

References 35 publications

A Numerical Model to Study the Response of Piles under Lateral Loading in Unsaturated Soils

A Numerical Model to Study the Response of Piles under Lateral Loading in Unsaturated Soils

Unsaturated structured soils: constitutive modelling and stability analyses

Wetting-induced instabilities: triggering mechanism and predisposing factors

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