Wave absorbing-boundary method in seismic centrifuge simulation of vertical free-field ground motion

Soudkhah, Mahdi; Pak, Ronald Y. S.

doi:10.1016/j.compgeo.2012.02.005

Cited by 8 publications

(4 citation statements)

References 21 publications

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“…Various studies performed on the effects of different boundary conditions showed the major effect of the container on the seismic response of soils [ 57 , 58 , 59 ]. Considering the inappropriate effects of the rigid lateral boundaries [ 60 , 61 ], artificial boundaries are generally used as absorbing boundaries to reduce the reflected and generated waves caused by the lateral boundaries of the box [ 62 , 63 , 64 ]. In recent years, the effects of different artificial boundaries such as duxseal materials, sponge, foam, and rubber sheets have been investigated on the seismic response of the soil [ 62 , 63 , 64 , 65 , 66 ].…”

Section: Introductionmentioning

confidence: 99%

“…Considering the inappropriate effects of the rigid lateral boundaries [ 60 , 61 ], artificial boundaries are generally used as absorbing boundaries to reduce the reflected and generated waves caused by the lateral boundaries of the box [ 62 , 63 , 64 ]. In recent years, the effects of different artificial boundaries such as duxseal materials, sponge, foam, and rubber sheets have been investigated on the seismic response of the soil [ 62 , 63 , 64 , 65 , 66 ]. Hasheminezhad et al (2022) [ 22 ], as one of the most recent studies, applied an absorbent layer of the foam in a rigid-box shaking table to evaluate the effects of two retrofitting methods of wall-type gravel and rubber drains on the liquefaction mitigation and studied the generated excess pore water pressures as a measure for such a purpose.…”

Section: Introductionmentioning

confidence: 99%

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Liquefaction Potential of Saturated Sand Reinforced by Cement-Grouted Micropiles: An Evolutionary Approach Based on Shaking Table Tests

et al. 2023

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Cement-grouted injections are increasingly employed as a countermeasure material against liquefaction in active seismic areas; however, there is no methodology to thoroughly and directly evaluate the liquefaction potential of saturated sand materials reinforced by the cement grout-injected micropiles. To this end, first, a series of 1 g shaking table model tests are conducted. Time histories of pore water pressures, excess pore water pressure ratios (ru), and the number of required cycles (Npeak) to liquefy the soil are obtained and modified lower and upper boundaries are suggested for the potential of liquefaction of both pure and grout-reinforced sand. Next, adopting genetic programming and the least square method in the framework of the evolutionary polynomial regression technique, high-accuracy predictive equations are developed for the estimation of rumax. Based on the results of a three-dimensional, graphical, multiple-variable parametric (MVP) analysis, and introducing the concept of the critical, boundary inclination angle, the inclination of micropiles is shown to be more effective in view of liquefaction resistivity for loose sands. Due to a lower critical boundary inclination angle, the applicability range for inclining micropiles is narrower for the medium-dense sands. MVP analyses show that the effects of a decreasing spacing ratio on decreasing rumax are amplified while micropiles are inclined.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Liquefaction Potential of Saturated Sand Reinforced by Cement-Grouted Micropiles: An Evolutionary Approach Based on Shaking Table Tests

et al. 2023

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“…Dynamic centrifuge tests employing Duxseal or other energy-absorbing materials along their boundaries mainly consist of two categories: earthquake induced events with relatively large ground movement amplitudes and ground-borne vibration problems with small amplitude ground movements. The majority of these studies focus on the former category and relate to free-field ground motions (Pak et al 2011;Soudkhah and Pak 2012;Zhu et al 2018), retaining wall behavior (Dewoolkar et al 2001;Madabhushi and Haigh 2019;Madabhushi and Haigh 2021), shallow foundations (Chakrabortty and Popescu 2012;Heron et al 2015;Adamidis and Madabhushi 2018;Kassas et al 2020;Kassas et al 2021;Adamidis and Madabhushi 2021), basement structures sited on liquefiable soil (Hughes and Madabhushi 2018), and underground structures (Cilingir and Madabhushi 2011;Chian and Madabhushi 2013;Chian et al 2014). The latter category has mainly related to railway induced ground-borne vibrations and soilstructure interactions, including vibrations from surface (Yang et al 2013b) and underground railways (Yang et al 2013a).…”

Section: Introductionmentioning

confidence: 99%

Effect of Duxseal on Horizontal Stress and Soil Stiffness in Small-Amplitude Dynamic Centrifuge Models

Cui

Heron

Marshall

2022

Geotechnical Testing Journal

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The constitutive behavior of soil is stress dependent. Therefore, geotechnical centrifuges are widely used to replicate full-scale stress fields, thereby ensuring the correct soil response within reduced-scale centrifuge models. A vibration absorbing material (such as Duxseal) is commonly employed to reduce the effect of reflected waves generated at the boundaries of rigid containers in dynamic centrifuge tests.However, such a material has the potential to deform laterally under the high horizontal stresses applied within centrifuge tests and consequently the initial at rest lateral earth pressure condition will not be maintained. A procedure to back-calculate the lateral earth pressure coefficient (𝐾) is presented in this paper.In addition, two experimental methods, which are implemented to evaluate 𝐾 by measuring the shear wave velocity from centrifuge-based air hammer testing and triaxial based bender element testing, are described.Results demonstrate that significant lateral earth pressure and soil stiffness reductions are observed within the upper soil region (top third of the model depth). In addition, the appropriate manipulation of the crosscorrelation method used to process shear wave signals is discussed and an empirical equation to predict the small strain shear modulus of the dry silica sand (HST95 Congleton sand) used in this study is provided.Outcomes of this study are directly applicable to small-amplitude dynamic centrifuge tests such as groundborne vibrations; some factors relating to large-amplitude seismic studies, such as soil inertial effects and

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“…One of the first contributions in absorbing boundaries, but still one of the most popular ones, is the fully-local, viscous boundary element by Lysmer & Kuhlemeyer (1969). This boundary provides the conceptual basis of most of the currently used elements, which exhibit various levels of efficiency with increasing levels of nonlocality, (Berenger, 1994;Soudkhah & Pak, 2012;Lee et al, 2012;Zheng et al, 2013;Duru & Kreiss, 2012). Moreover, many of these absorbing conditions have been used in recent FDs and FEs simulations of seismic regions, as large as the state of California and for frequencies up to 4.0 Hz, (Frankel, 1993;Komatitsch & Tromp, 1999;Min et al, 2003;Bielak et al, 2003;Komatitsch et al, 2004;Givoli, 2004;Frehner et al, 2008;Ichimura et al, 2009;Lee et al, 2009aLee et al, ,b, 2010Bielak et al, 2010;Chaljub et al, 2010;Lan & Zhang, 2011).…”

Section: Introductionmentioning

confidence: 99%

Seismic Wave Scattering Through a Compressed Hybrid BEM/FEM Method

Guarín-Zapata¹,

Gómez²,

Jaramillo³

2014

Preprint

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Approximate numerical techniques, for the solution of the elastic wave scattering problem over semi-infinite domains are reviewed. The approximations involve the representation of the half-space by a boundary condition described in terms of 2D boundary element discretizations. The classical BEM matrices are initially re-written into the form of a dense dynamic stiffness matrix and later approximated to a banded matrix. The resulting final banded matrix is then used like a standard finite element to solve the wave scattering problem at lower memory requirements. The accuracy of the reviewed methods is benchmarked against the classical problems of a semi-circular and a rectangular canyon. Results are presented in the time and frequency domain, as well as in terms of relative errors in the considered approximations. The main goal of the paper is to give the analyst a method that can be used at the practising level where an approximate solution is enough in order to support engineering decisions.

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Wave absorbing-boundary method in seismic centrifuge simulation of vertical free-field ground motion

Cited by 8 publications

References 21 publications

Liquefaction Potential of Saturated Sand Reinforced by Cement-Grouted Micropiles: An Evolutionary Approach Based on Shaking Table Tests

Liquefaction Potential of Saturated Sand Reinforced by Cement-Grouted Micropiles: An Evolutionary Approach Based on Shaking Table Tests

Effect of Duxseal on Horizontal Stress and Soil Stiffness in Small-Amplitude Dynamic Centrifuge Models

Seismic Wave Scattering Through a Compressed Hybrid BEM/FEM Method

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