Improved Approach for Modeling Nonlinear Site Response of Highly Strained Soils: Case Study of the Service Hall Array in Japan

Abstract

A nonlinear ground response analysis is conducted for the Niigata-ken Chuetsu-oki earthquake recorded at a free-field vertical array near the Kashiwazaki-Kariwa Nuclear Power Plant in Japan. A bidirectional site response analysis is carried out using LS-DYNA which allows user defined stress-strain relationships to dictate soil behavior subjected to dynamic loading. Dynamic soil behavior is characterized using a two-stage hyperbolic backbone curve implemented with modifications to consider the peak strength of soil layers as well as the strain at which the peak strength is fully mobilized. The effects of bidirectional input motions, strain rate, and the shape of the shear modulus degradation curves are investigated, and it is demonstrated that each factor can have a significant influence on the results.

Evaluation of One-Dimensional Multi-Directional Site Response Analyses Using Geotechnical Downhole Array Data in California and Japan

“…However, a bi-directional shaking model can more realistically reproduce the physical process in which seismic energy propagates to the ground surface and could potentially dissipate in all directions. The importance of bidirectional shaking in site response has been reported by many researchers such as Stewart et al (2008), Bolisetti et al (2014), and Motamed et al (2015Motamed et al ( , 2016. In this study, the recorded acceleration data at the deepest downhole sensors of each array were input in both horizontal directions (bidirectional shaking) simultaneously to better represent the complex multidirectional ground shakings.…”

“…Site characterization data for the SHA and KK5 were obtained from TEPCO (2007). Similar to the approach from Motamed et al (2016), an updated shear wave velocity profile was adopted for the SHA in this study to incorporate P-S suspension logging data, as described in Yee et al (2013).…”

“…For the SHA and KK5, seven (including two strong ground motions) and four (including two strong ground motions) sets of recordings were analyzed, respectively. The raw data obtained from TEPCO was filtered in the same manner as described by Motamed et al (2016). In total, 41 ground motions ranging in amplitude from PGA at the surface of 0.004g to 0.98g were utilized in this study and summarized in Table A1 in online Appendix A.…”

“…LS-DYNA is an advanced finite element (FE) program with versatile capabilities for modeling the dynamic response of soils. Furthermore, LS-DYNA has been used to approximate nonlinear 1-D SRA by other researchers (e.g., Bolisetti et al 2014, Motamed et al 2016) and has been shown in these investigations to produce results that can be considered reasonably accurate for practical applications.…”

Expanded Byrne model for evaluating seismic compression

“…The results from the analyses are in general accord with the records obtained after the earthquake and highlight the utility and versatility of the modified models. Tables Table 1: Assumed soil types and unit weights used in analysis (Motamed et al 2016) .......... 15 Table 2: KKNPP soil-specific calibration parameters for the Duku et al (2008) model. ........ 17 Table 3: Correction Factor, C2D, for Two-Dimensional Shaking (Lasley and Green 2012).…”