從鑽井資料看台北斷層在台北盆地的位置及其活動性

The Trace and Activity of the Taipei Fault Deduced from the Recent Deep Borehole Data in the Taipei Basin

林朝宗(Chao-Chung Lin) ； 李錦發(Jiin-Fa Lee)

《地工技術》 64期 (1997/12) Pp. 79-92

https://doi.org/10.30140/SG.199712.0008

摘要

近年來台北都會區發展迅速，無論是住宅建築、商業、市政府行政中心或交通建設，均不斷的往台北市東區發展，信義計畫區的開發在工程上常遭遇台北斷層的問題。台北斷層的位置及其活動性如何？對工程建設的安全有無影響？是當前大台北地區工程建設及防災與減災工作所急欲瞭解的事。本研究根據『台北盆地的地下地質及工程環境調查研究』深井鑽探、台北東區相關建設、台北大眾捷運系統的地質鑽探等資料，研判台北斷層的位置，綜合評估台北斷層的活動性及其對工程建設安全的影響。根據歷年來的鑽探成果，台北斷層在台北市信義計畫區至新生南路間的斷層線位置已逐漸明朗。而新生南路至中和、土城間由於缺乏新的深井資料，斷層線位置仍待查證。跨越台北斷層幾條捷運路線鑽探岩心柱狀圖資料顯示景美層頂部無異常錯動，因此可以推論至少松山層開始沈積以來（約一萬年前）台北斷層並未再活動。如果台北斷層在最近一萬年以來並未活動，則其對台北都會區的影響大為減輕。但台北斷層破碎帶甚為寬廣，當其潛伏在台北盆地地下較淺的位置時，仍會對超高層建築物的基礎及地下工程構成不利的影響。根據地質鑽探資料，台北盆地東區賴以支撐工程結構的景美層礫石層深度約在30～40m以下，厚度則僅數公尺至十餘公尺，礫徑小，且為基質支撐的礫石層，承載力較弱。尤其在信義計畫區，此礫石層甚至完全尖滅，超高層建築必須以基盤做為承載層，因此調查須深入瞭解台北斷層帶的特性，並妥為設計及施工。

關鍵字

台北斷層 ； 活動斷層 ； 信義計畫區

並列摘要

The Taipei Fault trending NE-SW and passing through southeastern part of the Taipei Basin has attracted much attention recently due to the rapidly eastward development of the Taipei metropolis. However, the trace and activity of the fault has long been the controversy among the geologists who have worked in this area due to the overlying hundreds meters thick of Quaternary basin deposits.Benefiting from the deep drilling project of the Taipei Basin conducted by the Central Geological Survey, the trace of eastern segment of the Taipei Fault in the basin is gradually raveled, while the western segment still remains inferred. Correlation of a series of deep boreholes which cross the trace of the Taipei Fault along several Taipei Rapid Transit lines shows that the contact between the Chingmei Gravel and the Sungshan Formation has not been offset by the Taipei Fault. This means that the Taipei Fault may have not been active since the beginning of the deposition of the Sungshan Formation, which has been dated to around 10,000 years before present.If the Taipei Fault has not moved since the recent 10,000 years, the activity of the fault is not longer the major threat to the construction and development of the metropolis. However, the wide fracture zone along the fault can be the disadvantage for the foundation of high-rise buildings and underground constructions while the fault passing through the shallow part of the Taipei Basin. The bearing capacity of the Chingmei Gravel in the eastern part of the Taipei Basin is apparently insufficient for high-rise buildings mainly because it is composed of fine, matrix-supported gravel with thickness less than 10 meters. Furthermore, the Chingmei Gravel fades out in the easternmost part of the basin, the Hsin-Yi District. The foundations of high-rise buildings have to be put on the basement rocks of the basin. The width and the properties of the fault zone should be accurately investigated during the site investigation for constructions.

並列關鍵字

Taipei Fault ； Active fault