Critical State Soil Mechanics for Cyclic Liquefaction and Postliquefaction Behavior: DEM study

Rahman, M.F.; Nguyen, Hoang Bao Khoi; Fourie, Andy; Kuhn, Matthew R.

doi:10.1061/(asce)gt.1943-5606.0002453

Cited by 48 publications

(11 citation statements)

References 56 publications

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“…Therefore, taking N ɛa as the failure criterion was more conservative due to its smaller soil deformation under this condition. The dynamic strength relationship of soil is defined as the relationship between the cyclic stress [for cyclic triaxial shear tests (σ d ) or for cyclic direct simple shear tests (σ τ )] and N f , and their relationship can be expressed as a power function (Rahman et al 2021) as σ d /p a or σ τ / p a = χ σ (N f ) −ϑ σ , where the normalized dynamic strengths (σ d /p a and σ τ / p a ) are defined as the ratio of dynamic strength to p a , and χ σ and ϑ σ are the fitting parameters. Then, ϑ σ was set at the same value (i.e., 0.15) for all sands, for example, calcareous (Xiao 2020), Snake River (Burbank et al 2013), Ottawa O'Donnell et al 2017b), Nevada , and Fraser River sands (Riveros and Sadrekarimi 2020b) with biotreatment or no treatment.…”

Section: Cyclic Resistance Strength Of Biotreated Soilsmentioning

confidence: 99%

Review of Strength Improvements of Biocemented Soils

Xiao

Zaman

et al. 2022

Int. J. Geomech.

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Microbially induced calcium carbonate precipitation (MICP) has attracted great attention recently for its ability to improve the mechanical properties of soils. Calcium carbonate (CaCO 3 ) precipitates that formed at the contact points and on the surface of particles or in the pore space of soil matrixes could increase the bonding strength, friction, and interlocking resistances due to the enhancement of the interparticle bonds, particle roughness, and packing density, and therefore, greatly improve the macroscopic performances of biocemented soils that were subjected to external loading. Strength is one of the key factors when determining the application of biotreatments in geotechnical engineering during the construction and operation periods. This study presented a systematic, objective, and extensive review of the strength of biocemented soils that was based on previous research. The improvement characteristics were comprehensively investigated under compression, tension, and static and cyclic shear conditions, for unconfined compressive (UCS), splitting tensile (STS), yielding, shear, and cyclic resistance strengths. Particle scale regimes were elaborated to interpret the improvement mechanism in the biotreatment and failure modes in biocemented specimens under external loading. Furthermore, the challenges of biocementation were discussed, and future investigations were envisioned.

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Section: Cyclic Resistance Strength Of Biotreated Soilsmentioning

confidence: 99%

Review of Strength Improvements of Biocemented Soils

Xiao

Zaman

et al. 2022

Int. J. Geomech.

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“…The CS data points in the classical e-log(p ) space formed a unique equation of e = 0.68 − 0.02 × p p a 0.73 ; where p a is the reference stress which is approximately 101 kPa [3,7,19]. The CSL is well known as the reference line to predict the liquefaction or instability behaviour of granular materials in the CSSM framework [2,3,69,70]. The specimen with the initial state starting above the CSL exhibits flow liquefaction under undrained conditions, whereas the specimen with the initial state starting below the CSL shows dilative or non-flow behaviour.…”

Section: Critical State Soil Mechanics Framework In Demmentioning

confidence: 99%

An Investigation of Instability on Constant Shear Drained (CSD) Path under the CSSM Framework: A DEM Study

2022

Self Cite

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Soil liquefaction or instability, one of the most catastrophic phenomena, has attracted significant research attention in recent years. The main cause of soil liquefaction or instability is the reduction in the effective stress in the soil due to the build-up of pore water pressure. Such a phenomenon has often been thought to be related to the undrained shearing of saturated or nearly saturated sandy soils. Notwithstanding, many researchers also reported soil instability under a drained condition due to the reduction in lateral stress. This condition is often referred to as the constant shear drained (CSD) condition, and it is not uncommon in nature, especially in a soil slope. Even though several catastrophic dam failures have been attributed to CSD failure, the failure mechanisms in CSD conditions are not well understood, e.g., how the volumetric strain or effective stress changes at the triggering of flow deformation. Researchers often consider the soil fabric to be one of the contributors to soil behaviour and use this parameter to explain the failure mechanism of soil. However, the soil fabric is difficult to measure in conventional laboratory tests. Due to that reason, a numerical approach capable of capturing the soil fabric, the discrete element method (DEM), is used to investigate the CSD shearing mechanism. A series of simulations on 3D assemblies of ellipsoid particles was conducted. The DEM specimens exhibited instability behaviour when the effective stress paths nearly reached the critical state line. It can be clearly observed that the axial and volumetric strains changed suddenly when the stress states were close to the critical state line. Alongside these micromechanical observations, the study also presents deeper insights into soil behaviour by relating the macro-observations to the micromechanical aspect of the soil.

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“…Alternatively, the discrete element method (DEM) proposed by Cundall and Strack 29 has been widely employed to investigate sand liquefaction behaviors. [30][31][32][33] The DEM could not only ensure the repeatability of simulation results and the stability of the deformed sample but also capture the particle-scale mechanism underlying the macroscopic stressstrain response. Therefore, the DEM was employed in this study to explore the evolution of sand reliquefaction resistance with residual EPWP under the mainshock-aftershock sequences and simultaneously reveal the mesoscopic mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, large shear strain was caused after initial liquefaction, and thereby the liquefied sample may not be stable and the cross‐section area of the tested sample may change greatly when employing conventional element test apparatus. Alternatively, the discrete element method (DEM) proposed by Cundall and Strack 29 has been widely employed to investigate sand liquefaction behaviors 30–33 . The DEM could not only ensure the repeatability of simulation results and the stability of the deformed sample but also capture the particle‐scale mechanism underlying the macroscopic stress–strain response.…”

Section: Introductionmentioning

confidence: 99%

Effects of reconsolidation degree on reliquefaction resistance under mainshock–aftershock sequences: A DEM investigation

Xie

Zhao

2022

Num Anal Meth Geomechanics

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Aftershock events may immediately follow mainshock events. In liquefiable deposits, the excess pore pressure caused by mainshock events may not dissipate completely in a short time interval between the mainshock and the aftershock. Sandy soil with different reconsolidation degrees (Ur) may present different reliquefaction resistances during the aftershock, which was not fully considered into the previous studies of reliquefaction. In this study, discrete element method (DEM) was employed to simulate a series of cyclic triaxial tests to evaluate the effects of Ur on reliquefaction resistance under mainshock–aftershock seismic sequence. The initially liquefied specimen was reconsolidated from two states with small and large residual shear strain respectively. Reconsolidated specimens reliquefied under different cyclic stress ratios (CSRs). Simulation results show that reliquefaction resistance increased gradually with increasing Ur, which was closely related to the previous residual shear strain during the first liquefaction event. Specimens that having large residual shear strain reliquefied easily, and the reliquefaction resistance of those specimens increased slightly with increasing Ur. On the contrary, reliquefaction resistance of the specimens that having small residual shear stain increased obviously with increasing Ur. The ratio of initial mechanical average coordination number to initial mesoscopic fabric anisotropy of reconsolidated specimens had a good correlation to the contraction potential and increased gradually with increasing Ur.

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Critical State Soil Mechanics for Cyclic Liquefaction and Postliquefaction Behavior: DEM study

Cited by 48 publications

References 56 publications

Review of Strength Improvements of Biocemented Soils

Review of Strength Improvements of Biocemented Soils

An Investigation of Instability on Constant Shear Drained (CSD) Path under the CSSM Framework: A DEM Study

Effects of reconsolidation degree on reliquefaction resistance under mainshock–aftershock sequences: A DEM investigation

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