Effects of spatial variability on soil liquefaction: some design recommendations

Popescu, Radu; Prévost, Jean‐Hérve; Deodatis, George

doi:10.1680/geot.1997.47.5.1019

Cited by 132 publications

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“…CPT values that fell outside a reasonable range (refer to Reference [14]) were eliminated. Then, CPT values were averaged over an interval of 10cm in depth.…”

Section: Evaluation Of Probabilistic Characteristics Of Soil Propertiesmentioning

confidence: 99%

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Risk assessment of an interacting structure–soil system due to liquefaction

Koutsourelakis

Prévost

Deodatis

2002

Earthq Engng Struct Dyn

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SUMMARYThe present study deals with the non-linear stochastic dynamic analysis of a soil-structure interacting system. The ultimate objective is to determine the risk of damage to the system due to liquefaction under a wide range of earthquake intensities. A Monte Carlo simulation approach is followed in conjunction with advanced ÿnite element procedures. The stochastic spatial variability of soil properties and the randomness of the seismic excitation are taken into account in order to estimate the statistics of the response, measured in terms of uniform foundation settlement and tilting. Speciÿcally, soil properties are modelled as non-Gaussian random ÿelds and seismic excitations as non-stationary random processes. The probabilistic characteristics of the stochastic ÿeld modelling soil properties are established from in situ tests. The risk of damage to the soil-structure system due to liquefaction is assessed by establishing fragility curves, which are of paramount importance for risk assessment and management studies of such systems. Fragility curves express the probability of exceeding various thresholds in the response. The relative e ect of the variability of various soil parameters on the variability of the response is also examined.

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“…CPT values that fell outside a reasonable range (refer to Reference [14]) were eliminated. Then, CPT values were averaged over an interval of 10cm in depth.…”

Section: Evaluation Of Probabilistic Characteristics Of Soil Propertiesmentioning

confidence: 99%

“…(b) Spectrum 2: a ÿctitious response spectrum rich in low frequencies (high periods) that is believed to be representative of a near-ÿeld event [14].…”

Section: Generation Of Seismic Ground Motion Time Historiesmentioning

confidence: 99%

Risk assessment of an interacting structure–soil system due to liquefaction

Koutsourelakis

Prévost

Deodatis

2002

Earthq Engng Struct Dyn

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“…This control by the loosest end of the spectrum appears to have been first reported on the basis of centrifuge studies of the Osterschelde closure caissons (Rowe and Craig 1976). Subsequent numerical studies have reinforced the conclusion in the case of cyclic mobility in hydraulically placed sand (Popescu et al, 1997) and static liquefaction of hydraulically placed sand. It appears that the controlling behaviour (characteristic property in limit states jargon) is dominated by the loosest 10-20% of the deposit.…”

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confidence: 74%

Discussion: Explosive compaction: design, implementation and effectiveness

Craig¹

2002

Géotechnique

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The authors have demonstrated with their video clips that a picture can indeed be worth a thousand words. Following the detonation of subsurface explosions a volume of the ground liquefies and the pore fluid seeks a route to the surface. The process of pushing an instability, through some fingering mechanism, to the surface can clearly take some considerable time-of the order of 2 mins. The subsequent outrush of soil and liquid from a pipe in an unpredictable location can be quite violent, and can also last for some time. While the overall result may be densification and consolidation of the ground, the pipe outlet itself may remain as a very loose zone. Is there any evidence of this from post-detonation probings? Authors' replyThe discusser has identified a potential source of loose zones within the densified mass. As noted, loose zones may be created by the flow of water displaced by reduction in void ratio due to densification. However, the largest volume changes occur during the first pass of explosive compaction, and the site illustrated in the video (Kelowna) was extremely loose (apparent relative density of about D r $ 25%), which emphasised this aspect of the ground response.The videos were shown to make the point that explosive compaction is really an induced consolidation, at least initially, with density change following explosive detonation on a very different and independent timescale. Attempts to simply correlate the achieved final density with the explosive weighting miss an important mechanism. However, the video perhaps overemphasised the prevalence of piping.Large-scale liquefaction is commonly associated only with the first few shots of the many used in compacting a site, and even then only with the very loose site. Typically we detonate only 9-12 holes in a single shot, and the first pass will correspondingly involve many shots to cover the entire area of the site. These later shots induce excess pore pressures, but settlements are reduced and the compaction of the site becomes more uniform. Wide-scale liquefaction is simply not seen then-indeed this might even be taken as proof of adequacy of treatment if liquefaction was the primary concern. Settlements may be induced some distance from the shot area once the soil in the area settling has been disturbed by its own shot. Typically after two or three passes of blasting the zone of settlement extends at approximately a 458 line from the deepest depth of blasting.Compaction uniformity is important because many compaction projects are related to liquefaction concerns, and liquefaction (and cyclic mobility) is controlled by the looser pockets in the soil. This control by the loosest end of the spectrum appears to have been first reported on the basis of centrifuge studies of the Osterschelde closure caissons (Rowe and Craig 1976). Subsequent numerical studies have reinforced the conclusion in the case of cyclic mobility in hydraulically placed sand (Popescu et al., 1997) and static liquefaction of hydraulically placed sand. It appears that the co...

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“…(5)) can be best represented by a Dirac delta function. For numerical simulation purpose the Dirac delta initial condition may be approximated by a multivariate Gaussian function with a mean of c and a very small standard deviation (w) as below: (10) Reflective boundary conditions are found to be the most appropriate for such FPK equations. They can be mathematically written as: (11) where, ζ is probability current and is given as: (12) …”

Section: Fpke Based Probabilistic Elasto-plasticity In Multi-dimensionmentioning

confidence: 99%

“…In the field of geotechnical engineering, probabilistic predictions are typically carried out using Monte Carlo simulation (MCS) technique [9,10,11,12,13]. However, this method is computationally very expensive for large scale non-linear elastic-plastic problems.…”

Section: Introductionmentioning

confidence: 99%

Probabilistic Elastic–Plastic Cam Clay Response of Soils

Sadrinezhad¹,

Sett²

2017

Proceedings of the 2nd World Congress on Civil, Structural, and Environmental Engineering

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-This study uses Cam Clay model to investigate the influence of uncertainties in soil properties on simulated undrained triaxial constitutive response. To this end, recently developed Fokker-Planck-Kolmogorov (FPK) equation approach to probabilistic elasto-plasticity is employed. The most general form of the three dimensional elastic-plastic constitutive rate equation is written in probability density space, resulting in a multi-dimensional FPK equation. The resultant FPK equation is specialized to undrained stress path. Given the second order statistics of the uncertainties in soil properties and assuming Cam Clay elastic-perfectly plastic constitutive model, the specialized FPK equations are solved to obtain second order accurate evolutionary (with pseudotime/ strain) joint probability density function of the stress response. Marginal statistics -marginal probability density function, marginal mean, and marginal standard deviation -of the stress components are then obtained from the multivariate probability density function using standard integration techniques.

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Effects of spatial variability on soil liquefaction: some design recommendations

Cited by 132 publications

References 0 publications

Risk assessment of an interacting structure–soil system due to liquefaction

Risk assessment of an interacting structure–soil system due to liquefaction

Discussion: Explosive compaction: design, implementation and effectiveness

Probabilistic Elastic–Plastic Cam Clay Response of Soils

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