英文篇名
Innovative Thinking for Characterizing Hydrogeological Features of Fractured Rock
作者
莊伯禹、魏倫瑋、黃胤中、柯建仲
關鍵字
裂隙岩體、無人飛行載具、質點影像測速法、熱脈衝流速儀、地球化學井測
摘要
近年來由於地下水污染整治、山區水資源調查與隧道工程的發展,致使裂隙岩體水文地質特性扮演著關鍵的角色,如何導入新穎技術與改良及進化既有技術,以獲取豐富的數據資料,並進一步強化數據分析與資料判讀,為本研究之核心主軸。本研究提出近期發展之3項新穎調查技術,包含露頭空拍調查、高精度裂隙透水性調查與地球化學特性調查,將透過調查案例探討與分析,說明各項調查技術之實際應用情形,提供未來裂隙岩體調查之新思維。
本研究首先應用無人飛行載具結合質點影像測速法來評估崩塌地的活動性,以嘉義縣中埔鄉一處崩塌地進行實作分析,結果顯示可於廣域範圍內找出判釋滑動體之地表岩體特徵及其活動性。第二部分,本研究提出之高精度地下水流速量測技術,應用於臺北市北投區義方站試驗井,透過一系列的現地試驗,包括岩心紀錄資料、聲波造影井測與熱脈衝流速儀試驗等,發現透水裂隙位置與裂隙分布密度(或破裂帶)未必直接相關,另為提高量測之精準度,本研究自行研發可加裝於流速儀底部的封塞水流分離裝置,分離10cm區段內外之水流,並成功於東部片麻岩試驗井進行初步測試。第三部分,本研究發展地球化學井測技術,並應用於臺東縣霧鹿試驗井場,試驗結果顯示地球化學井測資料有別於過去井測技術多偏向量測地球物理資訊,可提供更多關於溫度、酸鹼值、溶氧與氧化還原電位之垂向分布變化,更可瞭解岩層之地下水水質特性分布。
英文摘要
Characterization of hydrogeological features of fractured rock is important for the management of water resources, geotechnical engineering, groundwater remediation, petroleum engineering and geothermal production. Novel techniques could provide more precise supplementary data for enhancing the interpretation of hydrogeological features of fractured rock. Three investigation techniques were developed and conducted in this study, including the outcrop surveying technique, flowmeter measurement, and geochemical technique. Based on a case study, we assessed the applicability of these techniques, which in turn provided new insight into the investigation of fractured rock.
As the first phase of the investigation, UAV (Unmanned Aerial Vehicle) and PIV (Particle Image Velocimetry) techniques were combined to analyze 8 orthoimages taken between 2017 and 2019 to assess the activity of a landslide in Dongxing Villiage, Zhongpu Township, Chiayi County. This not only substantially improved the efficiency of the field investigation but also allowed the budget to focus on the active landslide bodies. For the second phase of the investigation, field tests, including core log, acoustic televiewer, and heat-pulse flowmeter test, were conducted in the Yifan borehole to identify the locations and transmissivity of permeable fractures. By comparing the flowmeter test results with those obtained from conventional techniques, we found that there was only a weak correlation between the high fracture-density zones and the permeable zones. Hence, we concluded that the fracture distribution and attitude data of the boreholes cannot be used to anticipate the actual fracture flow in the fractured rock. Heat-pulse flowmeter measurement is more efficient in locating the permeable fractures and quantifying their transmissivity. Moreover, a flow separating device, which can be installed at the bottom of the flowmeter, was developed to temporarily separate the inflow of a 10-cm segment from the other boreholes for acquiring more precise data. For the third phase of the investigation, geochemical loggings were conducted in 3 boreholes of the Wulu wellfield which provided the vertical distributions of the temperature, conductivity, dissolved oxygen, pH, and redox potential. The results indicated that the water quality of these boreholes was affected by the slurry, which was injected during the borehole drilling. In addition, these results can be used to locate the potential permeable fracture zones in the boreholes.