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標題: | 水文地質調查與分析技術於山岳隧道施工對地下水資源環境影響評估之應用 Application of Hydrogeological Survey and Analysis Techniques in the Assessment of Environmental Impact of Mountain Tunnel Construction on Groundwater Resources |
作者: | 高憲彰 Hsien-Chang Kao |
指導教授: | 游景雲 Jiing-Yun You |
關鍵字: | 隧道,湧水,水文地質,雙封塞試驗,音射式孔內影像,風險告知決策, Tunnel,Water inrush,Hydrogeology,Double packer test,Acoustic televiewer imaging,Risk-informed decision making, |
出版年 : | 2023 |
學位: | 博士 |
摘要: | 台灣山多平原少的先天環境造成許多公共工程需要於山岳地區建設。但由於造山運動的影響,導致山岳地區之地質年代年輕且岩層破碎程度高,形成複雜的水文地質環境,因此山岳地區之隧道工程常因遭遇惡劣之水文地質條件而影響工期,甚至造成全面停工或改變原規劃設計方案。
考量隧道施工中湧水風險之控制有賴於規畫設計階段詳實之水文地質調查及施工期間之預測分析,為此,本研究不僅專注於改進水文地質調查工具和資料解釋技術,同時制定了風險考量的隧道湧水估算流程,以作為隧道後續施工方法決策制定的參考。 (一)雙封塞水力試驗設備之改良 封塞水力試驗(Packer Test)是水文地質調查工作最常被使用的方法之一,可分為單封塞及雙封塞試驗,由於同一鑽孔不同深度處可能因地質條件不同而必須使用不同之試驗方法因應。傳統的封塞系統,當需要改變測試方法時,測試裝置必須被提升到地表進行拆卸或重新組裝,然後再下放至井內進行試驗,除耗時費力外,也增加了提吊過程對孔壁造成損傷的風險,繼而影響實驗之可靠度。 2合1充氣封塞系統的概念是在傳統雙封塞系統的下封塞上額外安裝一組壓力調節器和充氣管。此方式可以讓上下封塞得以獨立控制,有別於傳統兩個封塞同時加解壓的方式。這種設置使得系統可以在地下直接從雙封塞模式轉換為單封塞模式,反之亦然,並且可以根據需要為每個封塞設定不同的注入壓力,以適應特殊操作或特定需求。 為了測試系統的功能性,本研究在兩個鑽孔中進行測試。測試結果顯示,整個系統可以按照預期在鑽孔內輕鬆地從雙封塞模式轉換為單封塞模式,因此,藉由本改進後的系統於鑽孔內進行不同的封塞試驗,即使在地下水位較低或者只有極其有限的井測數據可用的情況下,仍然可以獲得所需的參數。 (二)孔內影像探測資料詮釋技術之改良 音射式孔內影像探測技術是一種地球物理井測工具,能夠揭露地下鑽孔孔壁的狀況,在現代地質調查中扮演著關鍵角色。然而這類設備提供的資訊往往偏重於孔壁二維平面影像的顯示和地層的結構特徵,缺乏立體深度感,對於地層整體地質組成樣態、地質構造變化程度、水文地質特性之詮釋效果有限。為改善此一現象,本研究乃藉由反射振幅數據之統計分析,進一步產出反射振幅雷達圖、振幅隨深度分布趨勢圖、區塊堆疊圖與鑽孔之類三維岩層結構顯影等,以協助調查人員對於地層組成架構、地質構造變化程度及水文地質特性之了解。 此外,藉由現場案例中反射振幅強度與岩心質量設計(RQD)、岩石強度和變形特性之比較,顯示反射振幅強度與RQD、岩石強度和變形特性等參數呈正相關,顯示藉由適當地解釋反射振幅數據能夠提供更有價值的場址訊息。 (三)基於RIDM之隧道中湧水量預測 為了降低隧道施工過程中湧水的風險,本研究以數值模擬方法為基礎,建立了一個風險考量的隧道湧水預測程序,並以蘇花改計畫中的東澳隧道作為示範案例,將影響隧道開挖出水的因子概分為水文地質條件與降雨補注,透過情境組合方式,藉由三維水文地質數值分析方式,模擬隧道在施工過程中於不同情境組合下之可能出水量。 分析結果顯示,雖然由於本計畫劃分之水文地質單元較大,無法完全反映局部小規模高透水地質單元或阻水構造之影響,導致在局部地區出現分析結果與實測值略有差異,惟整體而言,實測之湧水量仍大致落在預估之範圍內,顯示本文所導入之風險告知輔助決策確可有效應用於降低隧道施工中突發性湧水帶來之風險。 The geographical features of Taiwan, characterized by numerous mountains and limited plains, have caused many public infrastructures to be constructed in mountainous regions. However, tectonic activities have led to young and highly fragmented geological formations in these mountainous areas, creating complex hydrogeological conditions. Therefore, tunnel construction projects in these areas often encounter unfavorable hydrogeological conditions, not only affecting the construction schedule but sometimes having to terminate the project or modify the original design plans. To control groundwater inflow risks during tunnel construction, it is crucial to conduct hydrogeological investigations during the planning and design phases and to perform predictive analyses throughout the construction period. Therefore, this study not only focuses on improving hydrogeological investigation tools and data interpretation techniques but also develops a tunnel water inflow estimation process for risk assessment. This process serves as a reference for making decisions regarding subsequent tunnel construction methods. (1) Improvement of Double Packer Hydraulic Testing Equipment "Packer Test, a method widely used in hydrogeological investigations, can be categorized into single-packer and double-packer tests. Different test methods may be required at varying depths within the same borehole due to diverse geological conditions. For traditional packer systems, when a change in the testing method is necessary, the testing device must be lifted to the surface for disassembly or reassembly before being lowered back into the borehole for testing. This process is not only time-consuming and labor-intensive but also increases the risk of damage to the borehole wall during the lifting process, consequently affecting the reliability of the experiments. The concept of the 2-in-1 inflatable packer system involves installing an additional set of pressure regulator and inflation hose to the lower packer of a conventional double packer system. This modification enables the independent control of the upper and lower packers, deviating from the traditional method where both packers are pressurized simultaneously. With this setup, the system can be seamlessly transformed underground from double packer mode to single packer mode, and vice versa. Four types of packer set-up are presented, which are able to be used alternately, according to specific environmental needs. Moreover, different injection pressures can be applied to each packer as needed, allowing flexibility for specific operations or requirements. To assess the functionality of the system, studies were conducted in two boreholes. The test results showed that the entire system could be easily transformed in situ from a double-packer mode to a single-packer mode as expected within the boreholes. Therefore, through different packer tests conducted by using this modificed system, the required parameters could still be obtained even in situations where the groundwater level is low or when only extremely limited well data is available. (2) Improved Interpretation Techniques for Borehole Imaging Data Acoustic televiewer imaging technology is a geophysical well-logging tool that reveals the conditions of borehole walls underground, playing a crucial role in modern geological surveys. However, the information provided by this type of equipment tends to focus on displaying two-dimensional images of borehole walls and the structural features of the strata. It lacks depth perception and has limited interpretation regarding the overall composition, variations, and hydrogeological characteristics of geological structures. To improve this situation, by conducting statistical analysis of the reflection amplitude data, this study further generated reflection amplitude radar charts, depth-dependent amplitude distribution trend charts, block stacking diagrams, and three-dimensional visualizations of borehole rock layer structures. These outputs will be helpful for investigators to better understand the composition, structural variations, and hydrogeological characteristics of the formations. Furthermore, by comparing the reflection amplitude intensity with Rock Quality Designation (RQD), rock strength, and deformation characteristics from core samples in a field case, a positive correlation between reflection amplitude intensity and parameters such as RQD, rock strength, and deformation characteristics was observed. This demonstrates that appropriate interpretation of reflection amplitude data can provide more valuable site-specific information. (3) Prediction of Inflow during Tunnel Construction Based on RIDM To reduce the risk of water inrush during tunnel construction, this study establishes a risk-based tunnel inflow prediction procedure based on numerical simulation methods, using the case of the Dong'ao Tunnel in the Suhua Highway Improvement Project as an example. Factors influencing tunnel water inflow are classified into hydrogeological conditions and rainfall recharge. By utilizing scenario combinations and three-dimensional hydrogeological numerical analysis, the study simulates potential water inflow into the tunnel under various scenario combinations during the construction process. Due to the relatively large hydrogeological units defined in this project, they cannot fully capture the impact of local small-scale highly permeable geological units or water-resistant structures. This limitation results in minor discrepancies between the analysis results and actual measurements in specific local areas. However, the measured inflow quantities generally fall within the estimated range. This indicates that the risk-based approach introduced in this study can effectively be applied to mitigate the risk of water inrush during tunnel construction. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/91341 |
DOI: | 10.6342/NTU202304531 |
全文授權: | 同意授權(限校園內公開) |
顯示於系所單位: | 土木工程學系 |
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