Post-liquefaction undrained monotonic behaviour of sands: experiments and DEM simulations

Sitharam, T. G.; Vinod, Jayan S.; Ravishankar, B. V.

doi:10.1680/geot.7.00040

Cited by 108 publications

(43 citation statements)

References 17 publications

(27 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These values are similar to those frequently used in previous DEM simulations of quartz sands (e.g. [26,28]). A nonlinear Hertz-Mindlin model is used to describe the particle contact behaviors in loading and unloading.…”

Section: Discrete Element Simulation Of Cyclic Liquefactionsupporting

confidence: 87%

See 1 more Smart Citation

Microstructure evolution of granular soils in cyclic mobility and post-liquefaction process

Wang

Wei

2016

Granular Matter

View full text Add to dashboard Cite

Understanding the evolution of microstructure in granular soils can provide significant insights into constitutive modeling of soil liquefaction. In this study, micromechanical perspectives of the liquefaction process are investigated using the Discrete Element simulation. It is observed that during various stages of undrained cyclic loading, the soil exhibits definitive change in the load-bearing structure, indicated by evolution of the coordination number and non-affine displacements. A new particle-void fabric, termed as "centroid distance", is also proposed to quantify the evolution of particles and voids distribution in the granular packing. The fabric index is found to have strong correlation with cyclic mobility and post-liquefaction deformation of granular soils. Evolution of the fabric index indicates that particles and voids redistribute irreversibly before and after liquefaction. A highly anisotropic particle-void structure and loading-bearing capacity can be formed in the post liquefaction stage.

show abstract

Section: Discrete Element Simulation Of Cyclic Liquefactionsupporting

confidence: 87%

“…The influence of particle shape on liquefaction initiation was evaluated by Ashmawy et al [1]. Sitharam et al [26] also investigated the evolution of internal variables during post-liquefaction under undrained monotonic loading.…”

Section: Introductionmentioning

confidence: 99%

Microstructure evolution of granular soils in cyclic mobility and post-liquefaction process

Wang

Wei

2016

Granular Matter

View full text Add to dashboard Cite

show abstract

“…Such methods can simulate granular materials and provide microscopic measurements that are yet very difficult or impossible to obtain in laboratory experiments, and have become an increasingly important tool in the study of the mechanical behavior of granular materials. Numerous applications of DEM in studying sand liquefaction have verified DEM's capability of reproducing the undrained cyclic behavior of sand (e.g., [8,15,20,23,29,37]). Ng and Dobry [23], Dabeet et al [8], and Kuhn et al [20] all successfully modeled the generation of large shear strain at liquefaction using relatively simple DEM models.…”

Section: Introductionmentioning

confidence: 99%

DEM study of fabric features governing undrained post-liquefaction shear deformation of sand

et al. 2016

View full text Add to dashboard Cite

In an effort to study undrained post-liquefaction shear deformation of sand, the discrete element method (DEM) is adopted to conduct undrained cyclic biaxial compression simulations on granular assemblies consisting of 2D circular particles. The simulations are able to successfully reproduce the generation and eventual saturation of shear strain through the series of liquefaction states that the material experiences during cyclic loading after the initial liquefaction. DEM simulations with different deviatoric stress amplitudes and initial mean effective stresses on samples with different void ratios and loading histories are carried out to investigate the relationship between various mechanics-or fabric-related variables and postliquefaction shear strain development. It is found that wellknown metrics such as deviatoric stress amplitude, initial mean effective stress, void ratio, contact normal fabric anisotropy intensity, and coordination number, are not adequately correlated to the observed shear strain development and, therefore, could not possibly be used for its prediction. A new fabric entity, namely the Mean Neighboring Particle Distance (MNPD), is introduced to reflect the space arrangement of particles. It is found that the MNPD has an extremely strong and definitive relationship with the post-liquefaction shear strain development, showing MNPD's potential role as a parameter governing post-liquefaction behavior of sand.

show abstract

“…It was found that in well-graded soils the tendency to dilate was more pronounced than that exhibited by poorly graded soils. A recent study by Sitharam et al (2009) showed that the monotonic behaviour of liquefied soil was affected by the amplitude of the cyclic axial strain applied to cause liquefaction. On the other hand the post-liquefaction behaviour was found to be independent of the confining stress.…”

Section: Post-liquefaction Stress-strain Responsementioning

confidence: 99%

“…3. Effect of shape of p-y curve on the mobilised strength and stiffness of a pile foundation in a liquefied layer (solid lines schematically indicate the deflected shape of the pile at small and large displacement): (a) p-y curves from p-multiplier approach; (b) proposed strain-hardening p-y curves Sivathayalan & Vaid, 2004;Sitharam et al, 2009;Dash, 2010;Lombardi et al, 2014). Figure 3 illustrates the effect of different shapes of p-y curves on the seismic response of piled foundations.…”

Section: Introductionmentioning

confidence: 99%

Construction of simplified design p–y curves for liquefied soils

et al. 2017

View full text Add to dashboard Cite

In practice, laterally loaded piles are most often analysed using a 'beam-on-non-linear-Winklerfoundation' approach, whereby the soil-structure interaction is modelled by means of p-y curves. Although well-calibrated p-y curves exist for non-liquefied soils (e.g. soft clay and sand), the profession still lacks reliable p-y curves for liquefied soils. In fact, the latter should be consistent with the observed strain-stiffening behaviour exhibited by liquefied samples in both element and physical model tests. It is recognised that this behaviour is induced by the tendency of the liquefied soil to dilate upon undrained shearing, which ultimately results in a gradual decrease in excess pore pressure, and consequent increase in stiffness and strength. The aim of this paper is twofold. First, it proposes an easy-to-use empirical model for constructing stress-strain relationships for liquefied soils. This only requires three soil parameters which can conveniently be determined by means of laboratory tests. Second, it introduces a method for the construction of p-y curves for liquefiable soils from the proposed stress-strain model, based on the scaling of stress and strain into compatible soil reaction p and pile deflection y, respectively. The scaling factors for stress and strain are computed following an energy-based approach that is analogous to the upper-bound method used in classical plasticity theory. To validate the proposed p-y curves, results from a series of centrifuge tests are employed to back-calculate p-y curves for liquefied soils. The latter are compared with those obtained from the proposed method and the conventional p-multiplier approach.

show abstract

Post-liquefaction undrained monotonic behaviour of sands: experiments and DEM simulations

Cited by 108 publications

References 17 publications

Microstructure evolution of granular soils in cyclic mobility and post-liquefaction process

Microstructure evolution of granular soils in cyclic mobility and post-liquefaction process

DEM study of fabric features governing undrained post-liquefaction shear deformation of sand

Construction of simplified design p–y curves for liquefied soils

Contact Info

Product

Resources

About