Results of a Class C Blind Prediction Competition on the Numerical Simulation of a Large-Scale Liquefaction Shaking Table Test

Motamed, Ramin; Orang, Milad Jahed; Prabhakaran, Athul; Elgamal, Ahmed

doi:10.1061/9780784482780.032

Cited by 5 publications

(4 citation statements)

References 5 publications

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“…This diversity can satisfy the requirements of model tests for different rock properties, serving as a foundation for the selection of analogous materials in subsequent model tests. (2) The influence of each factor on the physical and mechanical parameters of the material was assessed using the extreme difference analysis method. The combination of iron powder and barite powder relative to the aggregate predominantly controlled the density and internal friction angle of the specimens.…”

Section: Results and Conclusionmentioning

confidence: 99%

“…Earthquake-induced instability frequently occurs in high and steep slopes characterized by variable morphologies and intricate rock formations. Indoor large shaking table tests [1][2][3][4][5] provide an enhanced means of replicating the entire landslide process. However, when conducting these large shaker tests in geological engineering, considerations must include the prototype's size and the appropriate scaling of its physical and mechanical parameters.…”

Section: Introductionmentioning

confidence: 99%

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Similar Material Proportioning Tests and Mechanical Properties Based on Orthogonal Design

Yang,

Dong,

Yang

et al. 2023

Materials

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Shaking table tests serve as an effective method to simulate landslides triggered by seismic activities. These laboratory experiments necessitate the use of materials that mimic those encountered in real-world scenarios. For this investigation, materials analogous to field conditions for the shaking table tests were formulated using quartz sand, barite powder, iron powder, gypsum, rosin, and alcohol. Within the model test compositions, iron powder, barite powder, and quartz sand acted as aggregates; gypsum functioned as an additive, and a solution of rosin and alcohol was employed as a binder. Employing the orthogonal design method, the physical and mechanical parameters of these analogous materials were ascertained through double-sided shear tests, as well as uniaxial compression and splitting tests. Subsequent analyses included extreme difference and regression assessments targeting the determinants influencing the physical and mechanical characteristics of these materials. The ultimate goal was to determine the optimal mixing ratios for the model test materials. The findings revealed that the physical and mechanical properties of analogous materials at varying ratios span a broad spectrum, fulfilling the criteria for distinct rock model experiments. A thorough examination of the factors impacting the physical and mechanical properties of these materials was undertaken, elucidating their respective influences. Based on the relative significance of each determinant on the mechanical attributes of the analogous materials, dominant factors were identified for a multiple regression analysis, from which the regression equations corresponding to the test ratios were derived.

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Section: Results and Conclusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Similar Material Proportioning Tests and Mechanical Properties Based on Orthogonal Design

Yang,

Dong,

Yang

et al. 2023

Materials

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“…Figure 3.23 shows the observed sand ejecta near the shallow foundation after Shake 1 in the Helical Pile test. Negative near-foundation settlement values, indicating the observed heave during the Baseline test for Shake 1 as a result of the local shear bearing capacity failure of the shallow foundation, were caused by reduced shear strength and stiffness of the liquefiable soil during shaking and manifested as near-foundation heave at all four measuring locations [Motamed et al 2020]; Jahed Orang et al 2021a]. Nonetheless, the positive nearfoundation settlement values indicated settled ground conditions in the Helical Pile test where no bearing capacity failure of the shallow foundation was observed during either shake test.…”

Section: Liquefaction-induced Foundation and Near-foundation Settlementsmentioning

confidence: 94%

“…In a recent paper, Motamed et al [2020] discussed the use of different numerical simulation techniques and their efficiency in predicting liquefaction-induced foundation and free-field settlements. The ejecta-induced settlement is manifested by the sand boils on the ground surface.…”

Section: Liquefaction-induced Foundation Settlementmentioning

confidence: 99%

Shake Table Tests on a Shallow Foundation on Liquefiable Soils Supported on Helical Piles

Orang¹,

Motamed²

2021

PEER Reports

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Extensive damage to buildings and infrastructure observed during past earthquakes resulting from the liquefaction of shallow saturated soil deposits underneath structures has demonstrated the necessity for further research in the area of liquefaction-induced ground movement effects. This study explores utilizing helical piles as a countermeasure to reduce liquefaction-induced foundation settlement and investigates their seismic performance in liquefiable grounds. Two large-scale shake table test series, one without any mitigation measures and one using helical piles, were conducted using the shake table facility at the University of California, San Diego. During each test series, the soil and superstructure models were extensively instrumented and subjected to two consistently applied shaking sequences. The model ground included a shallow liquefiable layer aimed at replicating the subsurface ground conditions observed in the past earthquakes in New Zealand, Japan, and Turkey. Liquefaction-induced foundation settlement mechanisms are broadly categorized as follows: (1) shear-induced, (2) volumetric-induced, and (3) ejecta-induced. In the first test series (referred to as the Baseline test hereafter), all these three components were realistically reproduced, while in the second test series (referred to as the Helical Pile test hereafter) the volumetric and ejecta-induced mechanisms were mainly mitigated, resulting in significant reductions in the foundation settlement. Results from the first test series (i.e., Baseline test) indicated that the flow velocity due to the hydraulic transient gradient displayed an upward flow in the loose layer, which explains the observed sand ejecta. This series of shake table tests resulted in an average total foundation settlement of 28 cm and 42.7 cm during two shaking sequences. The measured foundation settlements were compared to the estimated foundation settlement obtained from Liu and Dobry [1997] and Bray and Macedo’s [2017] simplified procedures. The observed foundation settlements generally were higher than the estimated values. In the second large-scale test series, an identical test setup to the first test series was used except for a group of four helical piles were attached to the shallow foundation to mitigate liquefaction-induced settlements. In this series of tests, a reduced excess pore-water pressure generation around the group of helical piles was observed and is mainly attributed to the increased relative density around their zone of influence as a result of installation. The foundation supported on helical piles underwent almost no differential settlement and tilt. A significant reduction in the total foundation settlement was achieved during the Helical Pile test series compared to the Baseline test series. This shake table project is the first experimental study that reproduced all the key mechanisms mentioned above including the effects of sediment ejecta, which have not been captured in prior experimental studies. In addition, this series of large-scale shake table tests provides a unique benchmark for the calibration of numerical models and simplified procedures to reliably estimate liquefaction-induced building settlements. Although this study introduced helical piles as a reliable and highly efficient measure to mitigate liquefaction-induced foundation tilt and settlement, the proper design nd application of helical piles in seismic areas still need thorough investigation due to possible amplified superstructure response.

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Large-Scale Shake Table Tests on a Shallow Foundation in Liquefiable Soils

Orang

Motamed

Prabhakaran

et al. 2021

J. Geotech. Geoenviron. Eng.

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Results of a Class C Blind Prediction Competition on the Numerical Simulation of a Large-Scale Liquefaction Shaking Table Test

Cited by 5 publications

References 5 publications

Similar Material Proportioning Tests and Mechanical Properties Based on Orthogonal Design

Similar Material Proportioning Tests and Mechanical Properties Based on Orthogonal Design

Shake Table Tests on a Shallow Foundation on Liquefiable Soils Supported on Helical Piles

Large-Scale Shake Table Tests on a Shallow Foundation in Liquefiable Soils

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