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

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• 作者：Hooman Torabi ; Mohammad T. Rayhani
• 关键词：Sensitive clay ; Nonlinear ground response ; Model calibration ; Soil constitutive model ; Period ; dependent amplification
• 刊名：Bulletin of Earthquake Engineering
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：15
• 期：1
• 页码：123-147
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geotechnical Engineering & Applied Earth Sciences; Environmental Engineering/Biotechnology; Civil Engineering; Geophysics/Geodesy; Hydrogeology; Structural Geology;
• 出版者：Springer Netherlands
• ISSN：1573-1456
• 卷排序：15

文摘

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 (\(\sigma_{vc}^{{\prime }} ,OCR\)). The calibrated relation was then successfully validated through material-specific site response analysis using the strong motion recordings from the 2010 Val-des-Bois 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.