Initial Shear Modulus of Remolded Sand-Clay Mixtures

Yamada, Suguru; Hyodo, Masayuki; Orense, Rolando P.; Dinesh, S. V.

doi:10.1061/(asce)1090-0241(2008)134:7(960)

Cited by 23 publications

(14 citation statements)

References 14 publications

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“…Yamada et al [22] also recommend n = 0.5 for granular soils and suggested that n = 1 for plastic clay-sand mixtures (they did not include a void ratio term in their formulation, which may explain why n is higher). All of these forms result in zero shear modulus when the effective stress is zero, which is unrealistic as it does not account for cementation, cohesion, capillary effects, and can be numerically problematic near the surface.…”

Section: Vertical Variation Of Soil Shear Modulusmentioning

confidence: 99%

Approximate solution for seismic earth pressures on rigid walls retaining inhomogeneous elastic soil

Brandenberg

Mylonakis

Stewart

2017

Soil Dynamics and Earthquake Engineering

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An approximate elasto-dynamic solution is developed for computing seismic earth pressures acting on rigid walls retaining continuously inhomogeneous elastic material and excited by vertically propagating shear waves. The shear modulus of the soil is represented as a nonlinear function of depth, in a manner that is consistent with established analytical and empirical relationships, while mass density and Poisson's ratio are assumed constant. Solutions are presented for a single wall and for a pair of walls spaced at a finite distance. A shape function characterizing the vertical variation of horizontal displacement of the soil column in the free-field is assigned, and simplifying assumptions regarding the dynamic vertical stresses and the vertical-to-horizontal displacement gradient are made to facilitate closed-form expressions for horizontal displacement and stress fields. These solutions are used to compute the distribution of dynamic horizontal earth pressure acting on the wall. A Winkler stiffness intensity relationship is then derived such that the proposed method can be extended beyond the boundary conditions considered herein. These solutions agree well with exact analytical elasto-dynamic solutions for inhomogeneous soil that are considerably more complicated to implement. Causes of differences between the solutions are discussed.

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Section: Vertical Variation Of Soil Shear Modulusmentioning

confidence: 99%

Approximate solution for seismic earth pressures on rigid walls retaining inhomogeneous elastic soil

Brandenberg

Mylonakis

Stewart

2017

Soil Dynamics and Earthquake Engineering

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“…where n % 1 for clays as proposed by Yamada et al (2008), and m = constant that depends on the clay properties, e.g., plasticity index and structure of the clay; A = a factor that depends on the structure of the clay; P 0 m ¼ mean effective stress. Equation (6) can be expressed in terms of detailed soil parameters as below:…”

Section: Calibration Of Soil Models For Site Response Analysismentioning

confidence: 99%

“…(7) along with the corrected G max of 32 Mpa, A ¼ 288 was computed. Since stiffness degradation of clays is typically insensitive to the variation of effective confining pressure (Kokusho et al 1982;Yamada et al 2008), the modulus-reduction (G/G max ) and damping curve (D) shown in Fig. 2 were applied to all clay layers throughout the model.…”

Section: Calibration Of Soil Models For Site Response Analysismentioning

confidence: 99%

Comprehensive nonlinear seismic ground response analysis of sensitive clays: case study—Leda clay in Ottawa, Canada

Torabi

Rayhani

2016

Bull Earthquake Eng

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A series of time domain nonlinear and frequency domain equivalent-linear ground response analysis was conducted for a representative site in Ottawa, Canada. The objective is to provide insight into the performance of different site response analysis approaches in predicting site amplification factors for the soft soil deposit over a wide range of shear strain. The surficial geology of the site is predominantly composed of the sensitive Leda Clay typical of this region in eastern Canada. A combination of results and observations from monotonic and cyclic laboratory tests, as well as field geophysical experiments, was used to calibrate the dynamic properties of the Leda clay, more specifically, the variation of the clay's shear stiffness (G max ) with the in situ stress state (r 0 vc ; OCR). The calibrated relation was then successfully validated through materialspecific site response analysis using the strong motion recordings from the 2010 Val-desBois earthquake and the shear wave velocity profile from borehole data. Comparison of the results with the hazard spectra proposed by NBCC 2010 reveals that the code-based site class E hazard spectra for the Ottawa area can be sufficient for seismic design, except around the natural site period. The results also suggest that the nonlinear analysis using the shear strength-adjusted hyperbola for modulus reduction and best-fitting trend to the laboratorybased damping would provide a reliable estimation of ground motion spectra at the natural site period. The performance of the ground response analysis alternatives for the sensitive clays, over a wide strain range was compared and discussed.

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“…where 1 for clays as proposed by Yamada et al (2008), and m=constant that depends on the clay properties, e.g., plasticity index and structure of the clay; A=a factor that depends on the structure of the clay; mean effective stress. Eq.…”

Section: Calibration Of Soil Models For Seismic Analysismentioning

confidence: 99%

“…4.4 along with the corrected Gmax of 32 Mpa, 288 was computed. Since stiffness degradation of clays is typically insensitive to the variation of effective confining pressure (Kokusho et al1982;Yamada et al 2008), the large-strain part of the modulus-reduction (G/Gmax) curve shown in Fig. 4.2 is applied to all clay layers throughout the model.…”

Section: Calibration Of Soil Models For Seismic Analysismentioning

confidence: 99%

A Hybrid Approach for Nonlinear Soil-Structure Interaction Analysis of Pile- Supported Bridges

Torabi¹

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The large-diameter reinforced concrete pile shafts are commonly designed as an economical solution for foundation of highway bridges in soft soils. The substructure method is a widely used technique for seismic SSI analysis of pile-supported bridges due to its remarkable computational efficiency. In the substructure modelling, the complexvalued impedance functions are used to represent the stiffness and energy dissipation characteristics of the soil-pile interaction system. While characteristics of the pile head impedance functions have been decently determined for linear soil-pile interaction, the effects of inelastic interaction on the impedance function still remain unclear. In fact, this study is an attempt to overcome the limitations of linear elastic soil and rigid soil-pile interface bonding assumptions that have been used in substructure analysis. This thesis aims to develop numerical and analytical frameworks to (i) investigate seismic response of a representative bridge superstructure supported by a large-diameter pile shaft under fully coupled inelastic soil-pile-structure interaction, and (ii) compute the equivalent-linear (EL) pile head impedance functions under the controlled dynamic and earthquake loading modes. Hence, a three-dimensional finite element (FE) model of the soil-pile system, as a rigorous direct method of SSI analysis is developed. The pile shaft lateral capacity is designed following to the AASHTO LRFD guidelines. The developed model is verified using data from centrifuge tests. In order to compute EL impedance functions from the continuum FE model, an algebraic solution is derived for the system of dynamic equilibrium equations in substructure analysis. In this frequency-domain solution, the Fourier transform of the force and displacement values obtained from the time-domain ii FE analysis are inserted, while the closed-form solution for the pile head impedance matrix is derived in terms of infinite series. Results of parametric FE analyses indicate that except for the extreme near-fault motions, the residual structural drift and the pile bending moment of the system would hardly exceed the design limits. The computed EL impedances provide insight into the damping evolution and stiffness reduction due to inelastic interaction over a frequency range of interest. As a key conclusion, it is shown that soil and interface inelasticity can drastically alter the impedance values compared to their fully elastic counterpart. iii ACKNOWLEDGEMENTS I would like to express my gratitude to my research advisor, Dr. Mohammad Rayhani, for his support, guidance, motivation and patience throughout the five years of my doctoral study. I would like to thank Professors Ertugrul Taciroglu from University of California, Los Angeles, Siva Sivathayalan and Dariush Motazedian from Carleton University and Julio angel Infante Sedano from university of Ottawa for serving on my dissertation committee and their insightful comments.Heartfelt thanks to my parents and little sister for their unconditional love and su...

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Initial Shear Modulus of Remolded Sand-Clay Mixtures

Cited by 23 publications

References 14 publications

Approximate solution for seismic earth pressures on rigid walls retaining inhomogeneous elastic soil

Approximate solution for seismic earth pressures on rigid walls retaining inhomogeneous elastic soil

Comprehensive nonlinear seismic ground response analysis of sensitive clays: case study—Leda clay in Ottawa, Canada

A Hybrid Approach for Nonlinear Soil-Structure Interaction Analysis of Pile- Supported Bridges

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