Laboratory and Three-Dimensional Numerical Modeling of Laterally Loaded Pile Groups in Sandy Soils
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RESEARCH PAPER
Laboratory and Three‑Dimensional Numerical Modeling of Laterally Loaded Pile Groups in Sandy Soils Amir Vakili1 · Seyed Mohammad Ali Zomorodian2 · Arash Totonchi1,3 Received: 3 June 2020 / Accepted: 1 October 2020 © Shiraz University 2020
Abstract The lateral response of piles embedded in soil is typically analyzed using the Winkler nonlinear springs method. The predictions of “load–displacement” response of the pile group are needed for a safe and economical design. In this method, the soil–pile interaction is modeled by nonlinear p-y curves in a way that the single pile p-y curve is modified using a p-multiplier for each row of piles in the group. The average p-multiplier is called the group reduction factor. Most research has focused on the behavior of laterally loaded single piles, though piles are most frequently used in groups. The present study was conducted to investigate the effects of various parameters, such as the pile spacing, different layouts, and the lateral load angle change as a new parameter, on the lateral response of piles, group efficiency, and p-multiplier factor in the group. Soil is modeled as an elastic–perfectly plastic material using the modified Mohr–Coulomb constitutive model. In addition, the Abaqus 3D model is validated using load–displacement results from laboratory tests of laterally loaded piles embedded in sand. The p-multiplier factor calculated from this study is well comparable with those of the full-scale tests on pile groups. However, based on the results, the calculated values of the p-multiplier factor at S/D = 3 (obtained from interpolation the values of group reduction factor at S/D= 2.5 and S/D = 3.5) are close to those recommended by the AASHTO, especially for 3 × 3 pile group. Keywords Pile group · Lateral load · p-y method · Group efficiency · Group reduction factor · Three-dimensional modeling
1 Introduction Pile foundations are often used when structures are placed on loose and weak soils. Therefore, pile foundations are used to tolerate the loads and transfer them to stronger layers of the soil through their septum bearing and reliance mechanisms. In addition, pile foundations are subjected to lateral loadings, such as collision forces and ship loading, lateral seismic forces, effects of waves, and lateral pressures of soils, due to liquefaction. Several methods have been proposed to model lateral pile group responses. For example, Ooi and Duncan (1994) developed a group amplification * Seyed Mohammad Ali Zomorodian [email protected] 1
Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
2
Department of Water Engineering, Shiraz University, Shiraz, Iran
3
Department of Civil Engineering, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran
procedure, which is neither able to estimate the distribution of loads among piles within a group nor take into account the pile group arrangement. The group effects in pile groups are taken into account by reducing the subgrade modulus. Pise and
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