Value-added study of subsurface prospecting data to applications of geotechnical engineering

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Project title

Code/計畫編號

MOST105-2218-E019-004

Translated Name/計畫中文名

井下探測資訊加值於大地工程應用研究

Project Coordinator/計畫主持人

Shih-Meng Hsu

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Harbor and River Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=12450456

Year

2016

Start date/計畫起

01-11-2016

Expected Completion/計畫迄

31-10-2017

Bugetid/研究經費

657千元

ResearchField/研究領域

土木水利工程

近幾年來國內山岳隧道開發工程、山區地下水資源潛能調查、地滑地崩塌機制調查等需求，陸續引進許多井下技術提升調查精度，至今累積相當多的井下探測成果資料。上述探測資料除了原本供給各計畫目標之使用外，如能再多加利用所獲得大量數據資料進行加值研究，將可使資料運用上達到最大化之目的。為善用現有調查資料數據，本研究從眾多技術中選擇資料量相對較多的孔內攝影與雙封塞試驗所獲得的資料進行加值分析研究，透過統計分析嘗試運用在評估岩體滲透性質之岩體分類系統建立議題上。本研究針對影響裂隙岩體透水性質的因子進行研究，透過383組水文地質試驗資料與雙變量分析，發現岩心品質指標、大地應力、剪裂泥含量與岩性等因子，某種程度主導裂隙岩體透水性質，但單一因子並無法完全主導此特性；取而代之，本研究整合所有影響因子，發展新的岩體滲透性指標的評分公式(HCB指標)，此指標與岩體透水係數獲得更高相關性，緊接著運用迴歸分析，建立臺灣中段與南段山區流域本土化岩體滲透係數值推估之經驗公式，HCB指標與岩層滲透性兩者之間遵循幕次定律。最後，本研究分析成果可應用在兩種水文地質參數調查工作上，第一個是在一個工程計畫可行性評估與初設階段，HCB透水性指標可在協助場址岩體滲透性質評估，檢視該區段岩體滲透性是否符合計畫調查目標；第二個應用是在已知HCB值情況下，各種迴歸分析公式則可以做為預測鑽孔隨深度連續透水係數值之工具，沿鑽孔垂向的透水係數分布，可以用來協助判別高透水/低透水區段，此對場址水文地質描述具有極大幫助。 In recent years, due to the project demands of tunnel construction, groundwater exploration in mountainous regions and landslide investigation, down-hole probing tools have been introduced into Taiwan to improve the prospecting accuracy. Up to the present, a pile of data has been taken from the subsurface exploration techniques in various projects. These in-situ measured data originally were provided for meeting the scopes of their own projects. If we take advantage of these data to create other benefits, data usage can be maximized. In order to make a good use of data, this study selected the data obtained from the borehole televiewer and double packer test to carry out a value-added application. Based on statistical analyses for these data, we conducted one research topic which is related to the establishment of rock mass permeability classification systems in fractured rock media. The procedure of this study was firstly to study influential factors which may affect the permeability of fractured rocks on a basis of 383 data sets from in situ hydraulic tests. Results from the bivariate analysis show that there are four factors, including, rock quality designation, geostatic stresses, fractures containing infillings of gouge content and lithology, affecting rock mass permeability. However, any single factor may not fully control rock mass permeability. Instead, a novel system called as “HCB-system”, which is a combination of four factors, was developed to obtain a better correlation on permeability. Subsequently, by regression analysis a variety of empirical models applicable to Taiwan’s mountainous regions for estimating rock mass permeability can be established. The regression results for all case studies demonstrated that a power law relationship exists between HCB and permeability with a feasible coefficient of determination. Finally, based on the results of present study, we can further perform two applications on hydrogeological investigations. The first one is that the proposed HCB system can be used to evaluate the degree of permeability of fractured rock during the feasibility and preliminary design stages of an engineering project. The second one is that these regression equations may provide a useful tool to predict permeability of fractured rocks in a given borehole based on measured HCB-values, which removes the cost on conducting hydraulic tests. The continuous data along the borehole can be produced in helping distinguish where permeable/impermeable zone is located. Thus, the vertical permeability profile is beneficial for characterization of site hydrogeology.

Keyword(s)

裂隙岩體
岩體滲透性
井下探測
雙變量分析
迴歸分析
fractured rock
rock permeability
well logging
bivariate analysis
regression analysis

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Value-added study of subsurface prospecting data to applications of geotechnical engineering

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