Numerical and experimental modeling of geomechanical behavior of partially saturated soils

AbstractThe Barcelona Basic Model (BBM) has been implemented in a finite difference-based computer program to simulate the behavior of unsaturated soils subjected to wetting. The BBM implementation was verified using analytical solutions, and the proposed model has been used to simulate the response of a compacted embankment under complete saturation and suction induced conditions. Numerical analyses indicate that considerable amount of total and differential settlements could develop at the top surface of the embankment. BBM is executed into FLAC2D extending a defined module for modified Cam Clay (MCC) and has been set up an analytical solution for suction-dependent stress and strain. Evaluating the effect of anisotropy and nonlinear apparent tensile strength in unsaturated soils, a modification to BBM formulation has been proposed and optimized by developing numerical analyses to reduce the size of elastic region of loading collapse (LC) curve. Then, an experimental study in the literature is investigated by utilizing comparative curves from BBM and modified BBM indicating well agreement with natural circumstances. As a result of the work presented in this research, finite difference codes with BBM and modified BBM has the capability of simulating the real behavior and is operational being applied to problems associated with earthen structures in unsaturated or partially saturated of expansive soils as a three-phases medium.

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Dynamic Analysis of Unsaturated Soils Subjected to Large Deformations

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.846.354 ◽

2016 ◽

Vol 846 ◽

pp. 354-359 ◽

Cited By ~ 3

Author(s):

Javad Ghorbani ◽

Majidreza Nazem ◽

John Phillip Carter

Keyword(s):

Constitutive Model ◽

Dynamic Analysis ◽

Unsaturated Soils ◽

Experimental Studies ◽

Mixture Theory ◽

Saturated Soils ◽

Deformation Analysis ◽

Mechanical Coupling ◽

Partially Saturated ◽

Partially Saturated Soils

This paper deals with the large deformation analysis of partially saturated soils subjected to dynamic loading. The so-called ‘mixture’ theory is employed to consider the hydro-mechanical coupling involved in this kind of problem. The finite element method is used to discretise the problem domain and the generalized-α algorithm is employed to integrate the governing equations over time. Some of the most challenging aspects of dynamic analysis of partially saturated soils will be discussed. One of the key challenges is selecting a consistent constitutive model within the theory of mixtures that can incorporate the pore suction forces into the description of stress. The necessity of such incorporation has frequently been reported in experimental studies of unsaturated soils. To tackle this problem, a unique strategy for integrating the constitutive model for unsaturated soils is adopted. Moreover, an absorbing boundary condition, which prevents wave reflection from rigid boundaries, is introduced and implemented into the numerical algorithm. Finally, a solution for the problem of dynamic compaction of soil in a partially saturated condition is presented.

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Biocolloid retention in partially saturated soils

Biologia ◽

10.2478/s11756-006-0163-0 ◽

2006 ◽

Vol 61 (19) ◽

Cited By ~ 18

Author(s):

Tammo Steenhuis ◽

Annette Dathe ◽

Yuniati Zevi ◽

Jennifer Smith ◽

Bin Gao ◽

...

Keyword(s):

Unsaturated Soils ◽

Saturated Soils ◽

Partially Saturated ◽

Partially Saturated Soils ◽

Visualization Experiments

AbstractUnsaturated soils are considered excellent filters for preventing the transport of pathogenic biocolloids to groundwater, but little is known about the actual mechanisms of biocolloid retention. To obtain a better understanding of these processes, a number of visualization experiments were performed and analyzed.

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Bearing Capacity Behavior of Skirted Foundations on Unsaturated Soils

E3S Web of Conferences ◽

10.1051/e3sconf/202131801014 ◽

2021 ◽

Vol 318 ◽

pp. 01014

Author(s):

Muthana S. Mohammed ◽

Mahmood R. Mahmood ◽

Saad F. A. Al-Wakel

Keyword(s):

Bearing Capacity ◽

Unsaturated Soils ◽

Experimental Models ◽

Performance Ratio ◽

Offshore Platforms ◽

Test Results ◽

Partially Saturated ◽

Partially Saturated Soils ◽

Improve Cost ◽

Installation Time

One of the most important factors for designing a safe foundation is the amount of bearing soil capacity and allowable settlement according to the type of structure. Therefore, in geotechnical engineering, the aim is to improve foundations' bearing capacity in many ways, some of which are expensive, and the other section is difficult to implement in some sites. Skirted foundations consider as an ideal solution to improve cost-wise soil tolerance by reducing materials and installation time. At present, there are several applications, including offshore platforms, bridges, turbines, oil installations, and high-load facilities. This paper investigates the behavior of carrying capacity of skirted foundations through experimental models on the sand. To examine the effect of various saturation conditions, various ratios of length to width of the footing base at different relative densities and different conditions for saturations dry, saturated, and partially saturated soils are considered. It was found that the magnitude of soil bearing enhances with increasing ratios of length to the width of the base of the footings for all cases. The increase in performance ratio increased linearly to 1.5 in footing depth (D/B) and then decreased according to the test results after this point.

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Constitutive Modeling and Discontinuous Bifurcation Assessment in Unsaturated Soils

Journal of Applied Mechanics ◽

10.1115/1.2202349 ◽

2006 ◽

Vol 73 (6) ◽

pp. 1039-1044 ◽

Cited By ~ 11

Author(s):

Ricardo Schiava ◽

Guillermo Etse

Keyword(s):

Porous Media ◽

Unsaturated Soils ◽

Material Model ◽

Partially Saturated ◽

Partially Saturated Soils ◽

Material Formulation ◽

Discontinuous Bifurcation ◽

Failure Predictions ◽

Partially Saturated Porous Media ◽

Stress States

In this work an elastoplastic constitutive theory for unsaturated soils is presented. The proposed material model is formulated in the general framework of the theory of porous media and of the flow theory of plasticity. The model is based on an extension of the well-known MRS Lade model whereby the suction and the effective stress tensor are introduced as additional independent and dependent stress components, respectively. Consequently the cap and cone yield conditions of the MRS Lade model both in hardening and softening as well as the internal evolution laws in these regimes are redefined to include the dependency on the suction. The paper illustrates the predictive capability of the extended MRS Lade model for partially saturated soils. Finally, the condition for discontinuous bifurcation in elastoplastic partially saturated porous media as well as the localized failure predictions of the proposed material formulation for different suctions and stress states are also analyzed and discussed.

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MODELING THE SOUTH ATLANTIC OCEAN FROM MEDIUM TO HIGH RESOLUTION

Brazilian Journal of Geophysics ◽

10.22564/rbgf.v31i2.27 ◽

2014 ◽

Vol 31 (2) ◽

Author(s):

Mariela Gabioux ◽

Vladimir Santos da Costa ◽

Joao Marcos Azevedo Correia de Souza ◽

Bruna Faria de Oliveira ◽

Afonso De Moraes Paiva

Keyword(s):

High Resolution ◽

Atlantic Ocean ◽

Large Scale ◽

South Atlantic ◽

Surface Relaxation ◽

The South ◽

Small Surface ◽

Basic Model ◽

Basic Set ◽

Set Up

Results of the basic model configuration of the REMO project, a Brazilian approach towards operational oceanography, are discussed. This configuration consists basically of a high-resolution eddy-resolving, 1/12 degree model for the Metarea V, nested in a medium-resolution eddy-permitting, 1/4 degree model of the Atlantic Ocean. These simulations performed with HYCOM model, aim for: a) creating a basic set-up for implementation of assimilation techniques leading to ocean prediction; b) the development of hydrodynamics bases for environmental studies; c) providing boundary conditions for regional domains with increased resolution. The 1/4 degree simulation was able to simulate realistic equatorial and south Atlantic large scale circulation, both the wind-driven and the thermohaline components. The high resolution simulation was able to generate mesoscale and represent well the variability pattern within the Metarea V domain. The BC mean transport values were well represented in the southwestern region (between Vitória-Trinidade sea mount and 29S), in contrast to higher latitudes (higher than 30S) where it was slightly underestimated. Important issues for the simulation of the South Atlantic with high resolution are discussed, like the ideal place for boundaries, improvements in the bathymetric representation and the control of bias SST, by the introducing of a small surface relaxation. In order to make a preliminary assessment of the model behavior when submitted to data assimilation, the Cooper & Haines (1996) method was used to extrapolate SSH anomalies fields to deeper layers every 7 days, with encouraging results.

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