A novel framework integrating downhole array data and site response analysis to extract dynamic soil behavior

ABSTRACT This short note examines the downgoing wave effect and the appearance of pseudoresonances in downhole array data. It is demonstrated that pseudoresonances, distinct from the resonances associated with outcrop conditions, occur for sites with a shallow velocity contrast (VC) or with little to no VC. An approach is outlined to distinguish pseudoresonances from outcrop resonances using the theoretical 1D transfer functions for within and outcrop boundary conditions, as well as the horizontal-to-vertical spectral ratio. This approach is applied to hypothetical shear-wave velocity profiles, as well as three downhole array sites. We establish the importance of distinguishing pseudoresonances from outcrop resonances when using downhole array data to evaluate the accuracy of the 1D site response. For the example downhole array sites shown, the pseudoresonances are not captured well by 1D analysis, whereas the outcrop resonances are captured well. We propose that when evaluating the accuracy of 1D site-response analysis using downhole array data, the comparisons of the empirical and theoretical responses only consider the frequency range associated with outcrop resonances.

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Site Response Analysis Using Downhole Array Recordings during the March 2011 Tohoku-Oki Earthquake and the Effect of Long-Duration Ground Motions

Earthquake Spectra ◽

10.1193/1.4000114 ◽

2013 ◽

Vol 29 (1_suppl) ◽

pp. 37-54 ◽

Cited By ~ 27

Author(s):

Byungmin Kim ◽

Youssef M.A. Hashash

Keyword(s):

Subduction Zone ◽

Site Response ◽

Soft Rock ◽

Response Spectra ◽

Response Analysis ◽

Soil Behavior ◽

Long Duration ◽

Downhole Array ◽

Downhole Arrays ◽

Array Recordings

Downhole arrays provide enhanced understanding of dynamic soil behavior and site response. Historically, downhole array recordings have been available only for earthquakes with relatively limited durations. New recordings from a number of KiK-net downhole arrays during the 11 March 2011, Mw 9.0, subduction zone earthquake near the east coast of Honshu, Japan, allow us to investigate dynamic soil characteristics and site response due to long-duration subduction zone earthquakes. Using these recordings, we perform one-dimensional site response analyses to evaluate the applicability of commonly used analysis approaches under long-duration earthquakes. We find that site response analyses capture key features of measured surface response spectra particularly at soft rock/stiff soil sites subject to long-duration motion. However, at softer soil sites, it appears that the modulus reduction is overestimated and site-specific characterization is needed.

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Evaluation of Site Response Analysis for Vertical Ground Motions Based on Downhole Array Records: Case Study of the Service Hall Array in Japan

Geotechnical Earthquake Engineering and Soil Dynamics V ◽

10.1061/9780784481462.039 ◽

2018 ◽

Author(s):

Austin Metz ◽

Ramin Motamed ◽

Kevin Stanton ◽

Kirk Ellison ◽

Ibrahim Almufti

Keyword(s):

Site Response ◽

Ground Motions ◽

Site Response Analysis ◽

Response Analysis ◽

Vertical Ground Motions ◽

Vertical Ground ◽

Downhole Array

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Rate-dependent soil behavior in seismic site response analysis

Canadian Geotechnical Journal ◽

10.1139/t07-090 ◽

2008 ◽

Vol 45 (4) ◽

pp. 454-469 ◽

Cited By ~ 8

Author(s):

Duhee Park ◽

Youssef M.A. Hashash

Keyword(s):

Shear Modulus ◽

Site Response ◽

Rate Dependence ◽

Site Response Analysis ◽

Response Analysis ◽

Soil Behavior ◽

One Dimensional ◽

Rate Dependent ◽

Seismic Site Effects ◽

Laboratory Test Results

One-dimensional site response analysis is widely used in estimating local seismic site effects. The soil behavior in the analysis is often assumed to be independent of the rate of seismic loading. Laboratory test results, on the other hand, indicate that cyclic cohesive soil behavior is influenced by the rate of loading. Three models of rate-dependent dynamic soil behavior were derived based on available laboratory data. The models were implemented and evaluated in a modified one-dimensional equivalent linear site response analysis approach. Results show that rate-dependent shear modulus and damping can have a pronounced influence on propagated weak ground motion but a secondary influence on propagated strong motion. Rate dependence of the damping ratio has a greater impact on the computed response than rate dependence of the shear modulus. This paper highlights the relevance of the compatibility between frequencies at which dynamic soil properties are measured and their use in site response analysis.

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