Using modified state surface approach to select parameter values in the Barcelona basic model

Zhou, Xiong; Xiao, Ming

doi:10.1002/nag.2112

Cited by 14 publications

(14 citation statements)

References 25 publications

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“…The maximum settlement regarding to self-weight occurred at mid-height of the embankment as the model was constructed gradually and the accumulative displacement was reported since the placement of each level. The results in both studies [37] with the present research) match very well, as are being observed in Fig. 7.…”

Section: Numerical Analysessupporting

confidence: 91%

Numerical and experimental modeling of geomechanical behavior of partially saturated soils

2021

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The 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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Section: Numerical Analysessupporting

confidence: 91%

Numerical and experimental modeling of geomechanical behavior of partially saturated soils

2021

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“…It was found that the initial yield stress for most soil specimens can be refined to be 200 kPa, and analysis was performed again for the new data. The numerical approach as discussed in Zhang and Xiao was used to solve the

X = {[\begin{matrix} left \\ left N (0) & left λ (0) & left β & left r & left p^{c} \end{matrix}]}^{T}

. Table shows the final results for the calibrated model parameters.…”

Section: Verifying Shape Of Yield Curve For Unsaturated Soils Using Rsupporting

confidence: 72%

Limitations of suction‐controlled triaxial tests in the characterization of unsaturated soils

Zhang

2015

Num Anal Meth Geomechanics

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SUMMARYBehavior of unsaturated soils is influenced by many factors, and the influences of these factors are usually coupled together. Suction-controlled triaxial (SCTX) tests are considered to allow researchers to investigate influences of individual variables on unsaturated soils under specified stress path with controls of stresses, pore water, and air pressures. In the past 50 years, SCTX testing method has been established as a standard approach to characterize constitutive behavior of unsaturated soils. Most important concepts for modern unsaturated soil mechanics were developed upon results from the SCTX tests. Among these, one of the most important contributions in the constitutive modeling of elasto-plastic behavior for unsaturated soils is the Barcelona basic model (BBM) proposed by Alonso et al. in 1990. The BBM successfully explained many features of unsaturated soils and received extensive acceptance.However, the SCTX tests are designed based upon the divide-and-conquer approach in which an implicit assumption is used: soil behavior is stress-path independent. However, it is well-established that unsaturated soil behavior is elasto-plastic and stress-path dependent. It is found that the SCTX tests in fact cannot control the stress path of an unsaturated soil during loading. This incapability, in combination with complicated loading/collapse behavior of unsaturated soils, makes the SCTX tests for characterizing unsaturated soil questionable. This paper discusses the limitations of the SCTX tests in the characterization of unsaturated soils. A possible solution to the problem was proposed based on a newly developed modified state surface approach. The discussions are limited for isotropic conditions.

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“…Wheeler and Sivakumar [27] experimentally verified the uniqueness of the virgin loading void ratio surface for unsaturated soils. Taking advantage of the uniqueness of the virgin loading surface and bypassing the incremental approach, the MSSA is a macro-level framework that simplifies the process of constitutive modeling and creates a clear guide for model development [24], model calibration [28], and comparisons across existing constitutive models [16,24,29]. Under isotropic stress conditions, the MSSA is illustrated by Fig.…”

Section: Overview Of the Mssamentioning

confidence: 99%

A Unified Two Independent Stress Variable Approach to Moisture-Change-Induced Unsaturated Soil Volume Change

Houston

Zhang

2023

E3S Web of Conf.

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In 1968, Matyas and Radhakrishna introduced the concept of the state surface, demonstrating that unsaturated soil volume change is dependent on two independent stress state variables, net total stress and suction. For decades the basic theory of unsaturated soils has been known, and a holistic view of the elastoplastic response of unsaturated soils, based on a modified state surface approach (MSSA), makes it clear that a method accounting for independent roles of net total stress and suction is required to quantify volume change of unsaturated soils. Still, reliance on pre-unsaturated-soil-mechanics-era methods persists, particularly within the geotechnical practice community. Unsaturated soil theory forms the basis for compelling arguments for discarding long-held efforts to classify unsaturated soils as exclusively expansive or exclusively collapsible with respect to volume change response. A more fundamental and unified approach to thinking about volume change of unsaturated soils supports the use of a consistent Stress Path Method to practice-based volume change analyses. Implications of geotechnical engineers’ continued reliance on expansive and collapsible soil classifications, often based on index-based correlations and non-stress-path appropriate laboratory testing, are explored. Recommendations for laboratory testing and modeling for moisture-change induced unsaturated soil volume change are made.

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Using modified state surface approach to select parameter values in the Barcelona basic model

Cited by 14 publications

References 25 publications

Numerical and experimental modeling of geomechanical behavior of partially saturated soils

Numerical and experimental modeling of geomechanical behavior of partially saturated soils

Limitations of suction‐controlled triaxial tests in the characterization of unsaturated soils

A Unified Two Independent Stress Variable Approach to Moisture-Change-Induced Unsaturated Soil Volume Change

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