圖書典藏及影音數位平台

規劃中之雙溪水庫係計畫供應北部區域東北角地區之雙溪、貢寮、瑞芳，以及基隆地區目標年(民國120年)公共給水及工業用水之重要規劃案。水庫集水區位於臺灣東北部，基隆市東南方15公里之新北市東側，地理位置詳如圖一。水庫主要水源為雙溪支流之丁子蘭溪並與貢寮淨水場攔河堰聯合運用，大壩位於新北市雙溪區魚行里丁子蘭坑，集水區面積約897公頃、計畫淹沒區面積約55公頃。 本計畫目標係依最新水利建造物檢查及安全評估技術，針對本水庫鄰近地區蒐集及整理地震記錄，評估水庫計畫壩址受震安全性，同時針對場址特性提出可能地震力、模擬地震波形與設計壩體的耐震力安全評估，做為大壩工程設計依據並將其分析過程及結果彙整為成果報告。

1、Preface The first purpose of this project is to routinely maintain the three strong motion seismographs located around designated dam site in Shuangxi, and keep them in good operational condition for recording earthquake ground motion. The recorded ground motions are analyzed for reference of dam design. The second purpose of this project is the performance of seismic hazard analysis for the Shuangxi area. The result of designated acceleration time history will be used to perform the safe analysis on the Shuangxi reservoir construction. 2、Install(Build three base) observation and maintenance of strong motion seismometer The three strong-motion seismographs were located in the dam north side, flooded area middle positionand flooded area the southern end position of the Shuangxi site for observation of strong motion. During the execution time, routine maintenance were carried out on 2013, November 20, December 12 and 2014, January 21, February 20, March 12, April 1. 3、Strong motion data collect and analyze (1) Strong motion data collection In these observed seismic data, 66 accelerograms were generated by 27 evens. Among these observation, 25 accelerograms recorded by SS-1, 17 accelerograms recorded by SS-2 and 24 accelerograms recorded by SS-3. The maximum and minimum among these earthquakes even are ML6.4 (no.1) and ML2.98 (no.7), respectively. The maximum epicenter distance is about 168.67km (no.1), and the minimum one is around 16.97km (no.5). (2) Strong motion data analysis The maximum PGA for SS-1 are 21.75 gal (EW), and 15.45 gal (NS), and 8.93 gal (UD), for SS-2 are 10.29 gal (EW), 11.70 gal (NS), and 5.29 gal (UD), for SS-3 are 11.12 gal (EW), 14.49 gal (NS), and 9.60 gal (UD) respectively. They were caused by earthquake no. 25. The even time and magnitude (ML) are, respectively, 2014/2/21 20hr 25min 16.70sec UT, 5.4ML, Epicenter distance and focal distance about the dam is 44.61 km and 76.3 km. 4、Seismic hazard analysis By probability-analysis method that based on the seismic area source, Shanchiao fault, subduction zone and Kueishantau volcano. The maximum probable earthquake magnitude is located on seismic zone S14B and the magnitude is ML 7.34. The distribution of decay curve is diverted, the truncated logarithm normal distribution function are corrected into 1σ, then calculate the earthquake magnitude for the 10,000, 950 and 475 years reoccurance period, the PGA is equal to 0.39g, 0.23g and 0.19g. 5、Design response spectrum and acceleration time history These design response spectrum was evaluated with the recurrence period of 10,000 years, the truncated logarithm normal distribution function are corrected into 1σ. The PGA of the corresponding acceleration time history is 310gal. 6、Permanent displacement and strain due to fault rupture After the rupture of the Shanchiao fault, the permanent displacement and strain are estimate. The increase stress of the dam is lesser than strength of concrete and bedrock under the dam. 7、Review of dam design by dynamic simulation The seismic wave propagation in the dam is simulated by the FEM model (ABAQUS). Under the extreme acceleration with PGA of 310gal, the tension stress larger than the strength of concrent at the corner and top of dam. The failure areas is small, the degree of damage is low and the failure zones do not across the dam.