臺灣自由場強震站場址分類之進一步研究

Further Study for Site Classification of Taiwan Free-Field Strong-Motion Station

蔡璧嬬(Bi-Ru Tsai)

指導教授 ： 李錫堤

國立中央大學/地球科學學院/應用地質研究所/碩士(2007年)

摘要

李錫堤等人﹙2001﹚以區域地質資料及少數的地質鑽探資料，參考1997 UBC的分類方法，針對當時已有的708處臺灣強地動觀測網﹙TSMIP﹚自由場強震站做地盤分類，提出臺灣地區的地盤分類圖。自該場址分類提出後，氣象局至94年已完成其中266個測站之調查工作，包括鑽探調查與波速度的量測。因此本研究利用這一些實測資料，以及更多的鑽探調查資料，進一步評估及更新各站之場址分類。
地表下三十公尺以內的地層特性，為主要影響震波放大效應的關鍵，故近年來場址效應研究也多以地表下三十公尺平均剪力波速度﹙Vs30﹚為評估場址條件的重要指標。本研究主要針對臺灣Vs30的分佈進行研究；首先搜集並檢核強震測站鑽探資料，以重新檢查過的高品質剪力波速度資料進行與SPT-N值關係研究，建立剪力波速度推估模式。藉由此模式對地調所工程地質資料庫中的各個鑽探資料進行不同深度剪力波速度之推估，並運用地質統計方法進行空間資料分析，採Kriging with varying local means方法對各個鑽孔所計算的Vs30進行內插，完成全臺灣之Vs30分佈圖，提出以Vs30為基礎之全臺灣強震站場址分類結果。

關鍵字

場址效應 ； 場址分類 ； 標準實入試驗 ； 剪力波速度 ； 克利金法

並列摘要

Based on the available geologic geomorphologic data and some borehole data, and refered the 1997 Uniform Building Code (UBC) provisions, Lee et al. (2001) classified 708 free-field strong-motion station sites of Taiwan Strong-Motion Instrumentation Program (TSMIP). They also published a geologic site class map for whole Taiwan. Till year 2005, the Central Weather Bureau has finished core drilling and PS logging for 266 strong-motion sites. This study utilize the 266 drilling and logging data and more other new data to evaluate and revise the site classification, and update the site class map of Taiwan.
Because the property of the upper 30 meters soil profile is a key point to the amplification of ground-motion, most of the researches on site effect consider the average shear-wave velocity in upper 30 meters (Vs30) as an important factor. The purpose of this study was mainly on mapping the distribution of Vs30 in Taiwan. First, I collect and examine the drilling and PS logging data for the strong-motion station, and recheck these data. Second, by using these rechecked high quality shear-wave velocity data and SPT-N value, I build a model to estimate the shear-wave velocity from SPT-N value. Third, by using this model, I estimate the shear-wave velocity of each drilling data from the Central Geological Survey Engineering Geology Database. Finally, I use a geostatistical analysis method called “Kriging with verying local means method” to generate a Vs30 distribution map of Taiwan with the estimated Vs30 value from each drilling data. Furthermore, a site classification result of Taiwan’s strong-motion stations is updated base on the Vs30 map.

並列關鍵字

krigiing ； shear wave velocity ； site class ； site effect ； SPT

參考文獻

Atkinson, G. M.﹙1993﹚Notes on ground motion parameters for Eastern North America: duration and H/V ration, Bulletin of the Seismological Society of America, 83, 1749–1759.

Boore, D. M., W. B. Joyner, and T. E. Fumal﹙1993﹚. Estimation of response spectra and peak accelerations from Western North American earthquakes: an interim report, U. S. Geological survey Open-File Report, 93–509.

Borcherdt, R. D.﹙1994a﹚Estimates of site-dependent response spectra for design﹙methodology and justification﹚, Earthquake Spectra, 10, 617-653

Chiou, B., and K. L. Wen﹙2006﹚Estimation of VS30 at CWB’s Free-Field Sites, Chiou and Youngs PEER-NGA Empirical Ground Motion Motion Model for the Average Horizontal Component of Peak Acceleration and Pseudo-Spectral Acceleration for Spectral Periods of 0.01 to 10 Seconds, Appendix C, C-1–C-5.

Darragh, R. B. and A. F. Shakal﹙1991﹚The site response of two rock and soil station pairs to strong and week ground motion, Bulletin of the Seismological Society of America, 81, 1885–1899