結合鑽探與地球物理方法調查八寶寮崩塌地之水文地質特性

Combining Drilling and a Geophysical Approach to Investigating the Hydrogeological Characteristics of the Babaoliao Landslide Area

張國欽(Kuo-Chin Chang) ； 葉信富(Hsin-Fu Yeh) ； 林榮潤(Jung-Jun Lin) ； 陳耐錦(Nai-Chin Chen) ； 柯建仲(Chien-Chung Ke) ； 陳榮俊(Jung-Chun Chen)

《中華水土保持學報》 50卷2期 (2019/06) Pp. 73-88

https://doi.org/10.29417/JCSWC.201906_50(2).0004

摘要

臺灣常在夏秋兩季遭受颱風豪雨之侵襲，山區因此常無預警的發生大規模的崩坍、滑動或土石流等自然災害。本研究以侵入式探勘及非侵入式探勘兩種地球物理方法合併使用，藉此可於投入長期監測系統前初步掌握崩塌地水文地質特性及潛在崩塌面，以提高邊坡防災之效能。本研究挑選位於臺灣嘉義縣之八寶寮崩塌地為研究場址，首先透過地質鑽探與岩心判釋，可瞭解研究區域地層特性為淺層1～2公尺為土壤與風化岩層，與地電阻影像剖面（RIP）測線判釋結果相似，且三處鑽孔（BH－01、BH－02及BH－03）皆顯示地表下深度約18.3至26.5公尺處，有厚度2～3公尺的剪裂泥分布。由BH－02及BH－03孔內岩體裂隙調查結果，可瞭解此處地層層面屬於高角度位態發育。另外，孔內地球物理探查顯示，此區域之淺層及深層地層材料為含泥量較多且膠結較差之泥質砂岩，因此易形成潛在之滑動面。而孔內地下水流速與流向調查方面則指出，BH－03鑽孔處之地層深處裂隙因與高水頭地層連通，於豪雨期間易造成地層孔隙水壓抬升而降低坡地之穩定性，且位於4公尺岩土交界面所形成之水流路徑則有可能形成潛在之滑動面。

關鍵字

鑽探 ； 地球物理法 ； 侵入式與非侵入式探勘

並列摘要

Heavy rainfall regularly occurs in Taiwan during the typhoon season in the summer and fall, and this rainfall causes large-scale natural disasters such as landslides, rockslides, and mudflows. Using a geophysical survey with both invasive and noninvasive methods, this study was conducted to preliminarily understand the hydrogeological characteristics of a landslide area and locate potential failure surfaces to strengthen slope failure prevention. The landslide area of Babaoliao region in Chiayi County of Taiwan was selected as the research site. Core drilling and analysis were conducted at the site; the results revealed that the 1-2-m-thick upper layer is composed of soil and weathered rock, which is similar to the conclusion reached through resistivity image profiling. Analysis of three boreholes (BH-01-3) determined a 2-3-m-thick layer of shear gouge in the subsurface layer between 18.3 and 26.5 m below ground. Investigation of the fractured rock masses in BH-02 and BH-03 revealed that the region has a large dip angle. Furthermore, geophysical survey of the boreholes demonstrated that both the outer and inner geological layers of the region are composed of silt-bearing marlstone that is not prone to cementation, causing a potential rupture surface. Inspection of BH-03 in terms of groundwater velocity and direction revealed a potential decrease in slope stability under heavy rain due to the rise in pore water pressure caused by the high hydraulic head connected to the borehole through fractures. The flow path formed by the soil-rock interface at 4 m below ground is a potential rupture surface.

並列關鍵字

Drilling ； geophysical approach ； invasive and noninvasive methods