ON THE CHARACTERISTICS OF NON-LINEAR SOIL RESPONSE AND DYNAMIC SOIL PROPERTIES USING VERTICAL ARRAY DATA IN JAPAN

✍ Scribed by GHAYAMGHAMIAN, M. R.; KAWAKAMI, H.

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 784 KB
• Volume: 25
• Category: Article
• ISSN: 0098-8847
• DOI: 10.1002/(sici)1096-9845(199608)25:8<857::aid-eqe592>3.0.co;2-r

✦ Synopsis

Non-linear response of the soil is investigated by comparing the spectral ratios (uphole/downhole) using weak and strong motions. Data from seven vertical arrays in Japan are analysed in this study. The frequency-dependent transfer function of soil is calculated as a ratio of the spectrum at uphole to the spectrum at downhole, considering the horizontal component of shear wave. In spectral ratio analysis auto-and cross-spectra are employed. The reduction in the predominant frequency of the transfer function with increases in excitation level reflects the non-linear response of the soil. Results of analysis demonstrate a significant non-linear ground response at six sites with surface PGA exceeding 90 gal. However, the results of one site show the linear response up to 130 gal surface PGA. Furthermore, the in situ strain-dependent soil behaviour is examined through the shear modulusshear strain relationship. When compared, the actual and laboratory results of the shear strain ~ shear modulus relationship are in agreement. Additionally, a good consistency between the tendency of reduction in shear modulus ratio with shear strain increases, and reduction of predominant frequency with ground motion increases, confirms the significance of non-linearity in site effects study.