Numerical modelling of the response of an unsaturated silty soil under wetting and gravitational loading processes

Rotisciani, G. M.; Lalicata, Leonardo Maria; Desideri, Augusto; Casini, Francesca

doi:10.1051/e3sconf/202019502012

Cited by 7 publications

(5 citation statements)

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“…Taking advantage of the symmetry of the model and of the perturbations applied, an axisymmetric analysis has been set up to reproduce the soil stress history prior to the loading of the pile. The details of this procedure are presented in Rotisciani et al [37]. Here, only the main aspects are reported.…”

Section: Stress History Of the Modelmentioning

confidence: 99%

“…The simulations are compared with the gathered data (surface movements, pore pressures, and volume water absorbed) with satisfying results. For the sake of brevity, the comparisons will not be shown here but they are thoroughly discussed elsewhere [19,37]. Figure 4 shows the profiles of the stresses and state variables during the analysis.…”

Section: Stress History Of the Modelmentioning

confidence: 99%

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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: Stress History Of the Modelmentioning

confidence: 99%

Section: Stress History Of the 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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“…R is defined as the ratio between p c and the intersection of the yield surface passing through the current stress state with the horizontal axis. Finally, the initial void ratio was determined once known the initial stress state and the position of the NCL related to the current S r (procedure described in detail in [19]).…”

Section: Activation Mechanism Of Volumetric Instabilitymentioning

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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“…The initial void ratio is determined consistently with the position of the NCL related to the current S r , for a fixed p c (Fig. 2, procedure described in detail in [53]), while it is assumed constant in the elastic domain, given the low compressibility of the material.…”

Section: Controllability Theorymentioning

confidence: 99%

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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Numerical modelling of the response of an unsaturated silty soil under wetting and gravitational loading processes

Cited by 7 publications

References 10 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

Wetting-induced instabilities: triggering mechanism and predisposing factors

Unsaturated structured soils: constitutive modelling and stability analyses

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