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1. Development of Experimental P-Y Curves from Centrifuge Tests for Piles Subjected to Static Loading and Liquefaction-Induced Lateral Spreading

   https://doi.org/10.37308/DFIJnl.20191120.212  

   Souri, Milad (October 2020, DFI Journal The Journal of the Deep Foundations Institute)

   The results of five centrifuge models were used to evaluate the response of pile-supported wharves subjected to inertial and liquefaction-induced lateral spreading loads. The centrifuge models contained pile groups that were embedded in rockfill dikes over layers of loose to dense sand and were shaken by a series of ground motions. The p-y curves were back-calculated for both dynamic and static loading from centrifuge data and were compared against commonly used American Petroleum Institute p-y relationships. It was found that liquefaction in loose sand resulted in a significant reduction in ultimate soil resistance. It was also found that incorporating p-multipliers that are proportional to the pore water pressure ratio in granular materials is adequate for estimating pile demands in pseudo-static analysis. The unique contribution of this study is that the piles in these tests were subjected to combined effects of inertial loads from the superstructure and kinematic loads from liquefaction-induced lateral spreading. 

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2. Integrated computational and full-scale physical simulation of dynamic soil-pile group interaction

   Jiang, Zhiyan (January 2019, Theses and dissertations)

   Three dimensional dynamic soil-pile group interaction has been a subject of significant research interest over the past several decades, and remains an active and challenging topic in geotechnical engineering. A variety of dynamic excitation sources may potentially induce instabilities or even failures of pile groups. Employing modern experimental and numerical techniques, the dynamics of pile groups is examined in this study by integrated physical and computational simulations. In the physical phase, full- scale in-situ elastodynamic vibration tests were conducted on a single pile and a 2×2 pile group. Comprehensive site investigations were conducted for obtaining critical soil parameters for use in dynamic analyses. Broadband random excitation was applied to the pile cap and the response of the pile and soil were measured, with the results presented in multiple forms to reveal the dynamic characteristics of the pile-soil system. In the computational phase, the BEM code BEASSI was extended and modified to enable analysis of 3D dynamic pile group problems, and the new code was validated and verified by comparison to reference cases from the literature. A new theoretical formulation for analysis of multi-modal vibration of pile groups by accelerance functions is established using the method of sub-structuring. Various methods for interpreting the numerical results are presented and discussed. Case studies and further calibration of the BEM soil profiles are conducted to optimize the match between the theoretical and experimental accelerance functions. Parametric studies are performed to quantify the influence of the primary factors in the soil-pile system. It is shown that the new 3D disturbed zone continuum models can help improve the accuracy of dynamic soil-pile interaction analysis for pile groups in layered soils. This study therefore helps to advance the fundamental knowledge on dynamic soil-pile interaction by improving the accuracy of current computational models, and contributes additional physical tests to the experimental database in the literature. The specific impedance functions generated herein can be immediately used in practice, and the underlying general 3D disturbed-zone computational framework can readily be applied to other pile group problems of interest to researchers and practitioners. 

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3. Seismic Performance of Pile-Supported Piers and Wharves Subjected to Foundation Deformations

   https://doi.org/10.1061/9780784482612.058  

   Souri, Milad; Khosravifar, Arash; Dickenson, Stephen; Schlechter, Scott; McCullough, Nason (September 2019, Ports 2019)

   The interaction of inertial and kinematic demands is investigated using data from five physical models of pile-supported wharves using a large-scale geotechnical centrifuge. The wharf structures in this study were subjected to a suite of recorded ground motions, therefore associated superstructure inertia, and earthquake-induced slope deformations of varying magnitudes. The observations from these tests were used to provide insights on how to estimate large bending moments that developed at pile head and at depths significantly below a commonly assumed point of fixity that are associated with deep-seated ground deformations. Design recommendations are proposed on how to combine inertial and kinematic demands in a manner that is representative of the global structure. 

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4. Estimation of lateral pile capacity for design of soil-structure interaction experiments

   Lamba, Kanika H.; Ashlock, J. C. (January 2016, 5th Canadian Young Geotechnical Engineers and Geoscientists Conference)

   McGreevy, Julian; De Groot, Maraika (Ed.)

   The accurate prediction and computational simulation of 3D multi-modal dynamic soil-pile interaction remains a significant challenge. As part of an ongoing research project to advance fundamental knowledge on this subject, dynamic soil-pile interaction experiments will be performed on single piles and pile groups, and new computational continuum models will be developed for seismic applications. To help calibrate the computational models, full-scale field tests are being planned for a single pile and a 2x2 pile group, including lateral vibration tests with small soil strains and quasi-static cyclic loading to failure. This paper describes the estimation of the ultimate lateral capacity of the single pile and 2x2 pile group at the selected project sites, required for designing the experiments. 

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5. Effect of soil-structure interaction on sand deposits supported by a sheet-pile wall under liquefied conditions

   Korre, Evangelia; Abdoun, Tarek; Zeghal, Mourad (September 2022, 10th International Conference on Physical Modelling in Geotechnics)

   Moonkyung Chung, Sung-Ryul Kim (Ed.)

   Retaining structures in waterfront areas are sensitive to seismically triggered liquefaction, leading to large deformations of the backfill and the retaining structure. The response of such systems depends heavily on the soil parameters, one of the most important being its relative density. This paper summarizes the key aspects of three centrifuge experiments performed at the Center for Earthquake Engineering Simulation (CEES) at Rensselaer Polytechnic Institute in 2020 as part of the experimental campaign for the Liquefaction Experiments and Analysis Project (LEAP-2020). The three models reflected the same prototype problem of a rigid floating sheet-pile quay wall supporting a 3-m-deep liquefiable soil deposit, of loose, medium dense and dense soil relative densities. The three models observed the same building technique and were subjected to the same target dynamic input motion. 

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