Effects of Spatial Variability on Liquefaction-Induced Settlement and Lateral Spreading

Montgomery, Jack; Boulanger, Ross W.

doi:10.1061/(asce)gt.1943-5606.0001584

Cited by 63 publications

(9 citation statements)

References 12 publications

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“…The scale of fluctuation (Vanmarcke, 1983) with respect to depth (θ y ) and horizontal distance along the model (θ x ) were set to 0.5 and 5.0 m, respectively. These scales of fluctuations are reasonable given that θ x is typically an order of magnitude larger than θ y in geologic materials (Phoon and Kulhawy, 1999) and have been used in other geotechnical random field model studies simulating the spatial variability of soils (Montgomery and Boulanger, 2016;Bong and Stuedlein, 2017). Figures (1a) and 2(a) present the reference V S profiles for model 1 at a COV of 20% and 5%, respectively.…”

Section: Model Domainmentioning

confidence: 62%

“…A spatially correlated Gaussian field is commonly used by researchers to represent natural variability in soils for geotechnical engineering applications based on observations from extensive subsurface investigations (e.g. Montgomery and Boulanger, 2016;Bong and Stuedlein, 2017). The first domain was generated as a single layer 10.0 m in depth and 70.0 m in length with a 0.5 m × 0.5 m grid size.…”

Section: Model Domainmentioning

confidence: 99%

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Numerical comparison of Rayleigh and Love full waveform inversion in characterizing soil spatial variability for near‐surface engineering applications

Mahvelati

Coe

2020

Near Surface Geophysics

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The use of surface wave testing for near‐surface engineering applications has increased in recent years. Typical surface wave analysis is based on the dispersion of surface waves in one‐dimensional layered models. One‐dimensional models are inappropriate for measurements at sites with appreciable lateral variability, a likely scenario in many engineering applications. Use of such models can subsequently undermine the reliability and accuracy of the surface wave results. Full waveform inversion (FWI) is a high‐resolution imaging technique that is proven to outperform the conventional dispersion‐based analysis of surface waves. Much of the near‐surface literature has focused on full waveform inversion of Rayleigh waves developed by the interaction of primary‐ and vertically polarized shear waves (P‐SV), and the capabilities of surface waves generated by horizontally polarized shear waves (Love waves) in mapping near‐surface spatial variabilities have not been fully explored. In this numerical study, full waveform inversion of Rayleigh and Love waves was performed on two different spatially correlated Gaussian random fields (mean VS of 200 and 500 m/s) to mimic the natural spatial variability of geologic materials. Each soil structure was produced at a low and high level of stiffness variability. Two sources with different frequency contents, 25 and 50 Hz, were used to evaluate the effects of source characteristics on the resolution of Rayleigh and Love waveform inversions. The inverted results from the high‐velocity domain demonstrated that Love waveform inversion using high‐frequency seismic sources outperforms Rayleigh full waveform inversion in detecting the shape and the velocities of horizontally deposited geologic materials. Results from the low‐velocity domain also confirmed that Love full waveform inversion was comparable or superior to Rayleigh full waveform inversion, though the performance difference was less significant. However, the 25‐Hz frequency inversions yielded superior results than the 50‐Hz frequency inversions for the low‐velocity domain because the dominant wavelength of the high‐frequency signals becomes so small that it offers an impractically small investigation depth.

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Section: Model Domainmentioning

confidence: 62%

Section: Model Domainmentioning

confidence: 99%

Numerical comparison of Rayleigh and Love full waveform inversion in characterizing soil spatial variability for near‐surface engineering applications

Mahvelati

Coe

2020

Near Surface Geophysics

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“…For the sand-like soils in the interbedded stratum, calibrations were developed for representative q c1Ncs values of 85 and 115, which correspond to CRR M7.5,σ=1 values of 0.12 and 0.16, respectively, based on the triggering correlation by Boulanger and Idriss (2015). These representative q c1Ncs values approximately correspond to the median values for the measured and inverse filtered CPT data, with the median value appearing to be a reasonable percentile for evaluating lateral spreading displacements of gently sloping ground with a uniform analysis model (Montgomery and Boulanger 2016). The shear modulus coefficient (G o ) was set to 585 for both calibrations to match the in-situ V s at the middle of the stratum, the apparent relative density (D R ) was estimated as 48 and 61% using the relationships in Idriss and Boulanger (2008), and the contraction rate parameter (h po ) was iteratively adjusted to obtain the target cyclic strength in 15 uniform cycles of undrained direct simple shear (DSS) loading.…”

Section: Constitutive Model Calibrationsmentioning

confidence: 97%

Liquefaction Evaluation of Interbedded Soil Deposit: Çark Canal in 1999 M7.5 Kocaeli Earthquake

Boulanger

Munter²,

Krage

et al. 2019

J. Geotech. Geoenviron. Eng.

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The performance of Çark Canal in the 1999 M=7.5 Kocaeli earthquake is evaluated using common liquefaction vulnerability index (LVI) methods, a nonlinear dynamic analysis (NDA) method, and a Newmark sliding block method to examine possible factors contributing to why different analysis approaches often overestimate liquefaction effects in interbedded deposits. The characterization of the interbedded fluvial stratum based on cone penetration test (CPT) data utilized an inverse filtering procedure to correct CPT data for thin layer and transition zone effects. Common LVIs computed using the measured and inverse filtered CPT data with a site-specific fines content calibration show that the combination of these two steps reduce the LVIs by 30-50% for this site and seismic loading. Twodimensional NDAs are performed using stochastic realizations for the interbedded stratum and the PM4Sand and PM4Silt constitutive models for the sand-like and clay-like portions, respectively.Computed deformations are evaluated for their sensitivity to stochastic model parameters, the cyclic strength assigned to the sand-like soils, the undrained shear strengths assigned to the clay-like soils, the level of shaking, and other input parameters. Newmark sliding block analyses are performed with different allowances for how inter-bedding influences the composite strength of the interbedded stratum.The differences between results obtained with these analysis methods, along with those presented by Youd et al. (2009), provide insights on how the various factors can contribute to an over-estimation of ground deformations in interbedded deposits of sands, silts, and clays.

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“…For each stratum, 33 rd and 50 th percentile values for qc1Ncs or su/σ'vc were obtained based on all CPTs at the site. The 33 rd to 50 th percentile range is expected to encompass reasonably unbiased estimates of expected responses based on the findings of Montgomery and Boulanger (2016) for NDAs involving an evaluation of post-liquefaction reconsolidation settlements.…”

Section: Calibration Of Constitutive Modelsmentioning

confidence: 99%

System Response of an Interlayered Deposit with Spatially Preferential Liquefaction Manifestations

Bassal

Boulanger

2021

J. Geotech. Geoenviron. Eng.

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The Canterbury Earthquake Sequence produced a spatial pattern of liquefaction-induced surface ejecta at an open field along Palinurus Road in Christchurch, New Zealand, that would not be expected based on simplified liquefaction evaluation procedures. Half the site discharged sand boils and the other half did not. Two-dimensional fully-coupled nonlinear dynamic analyses (NDAs) are performed to examine why simplified one-dimensional liquefaction vulnerability indices (LVIs) over-estimated liquefaction manifestations at this site for the 2010 Darfield and 2011 Christchurch earthquakes and did not distinguish between areas with and without surface ejecta. The NDAs use the PM4Sand and PM4Silt constitutive models for sand-like and clay-like portions of the subsurface, respectively, within the FLAC finite difference program. Material parameters are obtained from in-situ geophysical and cone penetration test (CPT) data. A sensitivity study is performed to assess the influence of: (1) representative soil property selections and the use of a CPT inverse filtering procedure to correct for thin-layer and transition zone effects, (2) ground motions developed by two distinct methods (i.e., recordings and physics-based simulations), and (3) model assumptions affecting diffusion during reconsolidation. Ground deformations and flow patterns during and after ground shaking are examined. The results provide insights on how stratigraphic details and other factors can affect the system response and dictate the degree and extent of liquefaction surface manifestations.

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Effects of Spatial Variability on Liquefaction-Induced Settlement and Lateral Spreading

Cited by 63 publications

References 12 publications

Numerical comparison of Rayleigh and Love full waveform inversion in characterizing soil spatial variability for near‐surface engineering applications

Numerical comparison of Rayleigh and Love full waveform inversion in characterizing soil spatial variability for near‐surface engineering applications

Liquefaction Evaluation of Interbedded Soil Deposit: Çark Canal in 1999 M7.5 Kocaeli Earthquake

System Response of an Interlayered Deposit with Spatially Preferential Liquefaction Manifestations

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