Laboratory Investigation of the Pre- and Post-Cyclic Volume Change Properties of Sherman Island Peat

Shafiee, Ali; Brandenberg, Scott J.; Stewart, Jonathan P.

doi:10.1061/9780784412787.015

Cited by 6 publications

(6 citation statements)

References 11 publications

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“…Peat slurry was then poured from buckets onto the sand and smoothed with trowels at elevations where sensors would be placed. The amount of peat slurry required to achieve the target peat thickness after consolidation in-flight was based on observations from the Schaevitz centrifuge test program (Cappa et al 2015), laboratory consolidation studies (Shafiee et al 2013), and settlement predictions using Settle 3D (Rocscience 2014). The peat slurry was too weak to support the clay levee; therefore, a layer of Nevada sand ( γ dry = 17 kN/m 3 ) was placed on top of the peat to pre-consolidate the material over the course of three days.…”

Section: Model Construction and Load Applicationmentioning

confidence: 99%

Centrifuge Testing of Model Levees atop Peat: Experimental Data

et al. 2016

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Four large-scale centrifuge tests were performed at the NEES@UCDavis equipment site to study the cyclic behavior of levee structures resting atop soft organic peat. The model configurations using a non-liquefiable levee focused on the seismic deformation potential of peat during primary consolidation and secondary compression. The tests performed with a sandy levee studied the liquefaction potential of saturated loose sand fill overlying soft peat as well as the levee-peat-interaction under different loading conditions. The models were subjected to scaled ground motions representative of the Sacramento/San Joaquin Delta. System instrumentation consisted of linear potentiometers, pore pressure sensors and accelerometers. Slow data recorded at 1 Hz document the settlements during spin up, application of ground motions, and spin down. Fast data sampled at 4,167 Hz measured the dynamic response of the system, the excess pore pressure increase and immediate settlements. The project is archived at the NEES data repository under nees.org/warehouse/project/1161 .

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Section: Model Construction and Load Applicationmentioning

confidence: 99%

Centrifuge Testing of Model Levees atop Peat: Experimental Data

et al. 2016

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“…Researchers have evaluated the modulus reduction and damping behavior of peat (e.g., Wehling et al 2003, Kishida et al 2009a) and studied site effects on ground motions for Delta levee cross sections (Kishida et al 2009b). However, other effects such as cyclic pore pressure generation and related strength loss and volume change have only recently been studied at laboratory scale (Shafiee et al 2013). Field performance data is generally lacking, with the exception of a few case histories from Japan of poor performance of levees on peat and liquefiable sands (e.g., Sasaki 2009).…”

Section: Introductionmentioning

confidence: 99%

Dynamic Response of a Model Levee on Sherman Island Peat: A Curated Data Set

et al. 2014

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A model levee resting atop soft compressible peaty organic soil in the Sacramento/San Joaquin Delta was shaken by forced vibration to study the seismic deformation potential of the underlying peat and measure dynamic levee-peat interaction. Forced vibration testing occurred over a frequency range of 0 to 5 Hz and produced force amplitudes applied to the embankment crest that induced elastic to nonlinear levee-foundation responses. Available data include acceleration records from sensors mounted on the model levee and on the ground surface near the model levee, and acceleration and pore pressure measurements from sensors embedded in the underlying peat. A remote data acquisition system measured settlements and pore pressures over a span of more than a year, encompassing time before and after the dynamic testing. Small pore pressures were generated in the peat during testing although embankment settlements from cyclic loading were small.

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“…Rayleigh wave velocity measured at the site was only 26m/s and water contents were as high as 700% in the saturated peat, indicating the unusually soft nature of these organic materials. Consolidation testing of the saturated peat (Shafiee et al 2013) gives a C c of 3.9 and a C r of 0.4. The model levee is 1.8m (6ft) tall, 12.2m (40 ft) long along the base, 4.9m (16ft) long along the crest with 2:1 sideslopes, and 3.7m (12 ft) wide (out of plane).…”

Section: Test Specimenmentioning

confidence: 99%

“…High secondary compression is a common feature of peat soil that is well documented in the literature (e.g., Mesri and Ajlouni 2007), and is usually attributed to high void ratio of peat, high ratios of the index of secondary compression to the compression index (C α /C c ), and high initial permeability of the peat (Mesri et al 1997) . In laboratory oedometer tests performed on piston samples retrieved from the site (Shafiee et al, 2013), distinguishing primary consolidation from secondary compression using Casagrande's (1938) procedure was difficult due to the high c α . The piezometers were disconnected from the remote data acquisition system on August 24 th , connected to a different data acquisition system utilized during dynamic testing of the embankment, and subsequently reconnected after dynamic testing on August 29 th .…”

Section: Test Datamentioning

confidence: 99%