裂隙岩體破裂面參數與滲透性調查技術之研究

Investigation Technology for fracture parameters and permeability of fractured rock masses

宋政輝(Cheng-hui Sung 宋政輝)

指導教授 ： 王泰典

國立臺北科技大學/工程學院/資源工程研究所/碩士(2012年)

https://doi.org/10.6841/NTUT.2012.00269

摘要

水文地質模式為描述地下水流動和溶質傳輸行為的重要途徑，亦為水利資源與地下空間開發應用的關鍵技術。自然岩體中存在許多不連續面，如裂隙、層面、節理面與片理面等，使其力學與水力行為呈現異質性與異向性，造成模擬、分析的差異，甚至於工程設計與施工的困難，如何掌握場址水文地質特性，選擇適當的滲流模式採用適度的描述尺度加以預測分析，為水文地質研究自概念模式、敘述模式邁向水力學模式與數值模擬的關鍵里程。
本研究以裂隙岩體網絡(discrete fracture network，DFN)模式作為描述場址水文地質特性之前驅，設計一水文地質現地試驗井場，佈置鑽孔並進行一系列裂隙空間分佈參數調查以及水力參數試驗，探求裂隙岩體等值水力傳導係數。為獲得DFN模式所需的參數，透過室內試驗求取破裂面力學參數與幾何參數特性，最後依據裂隙參數建立二維裂隙網絡模式分析、評估與探討水文地質滲透特性。
研究結果顯示不同水力試驗方法於本研究粉砂岩地層求得的場址等值水力傳導係數，因次介於10-5~10-7 m/s，差異達二個數量級以上；就單井水力試驗結果視之，不同裂隙組合下試驗所得的水力傳導係數介於10-5~10-9 m/s，差異達四個數量級以上，顯示裂隙分佈顯著影響場址水文地質特性。本研究以離散裂隙網絡模式經調查破裂面參數後佈置井場，佐以現地水文試驗求取場址水力傳導係數，描述裂隙岩體水文地質特性在研究井場確實適當可行。
數值模擬結果顯示：依據井場附近岩體破裂面參數調查結果，模擬生成的離散裂隙網絡，鑽孔遭遇的裂隙數量與現場實測結果一致，模擬求得的水力傳導係數因次介於10-5~10-7 m/s，亦與現地水力試驗所得結果相近。本研究有關裂隙岩體水文地質特性調查的井場建置、現地試驗、室內試驗以及相關模擬分析技術可相互驗證，亦可提供水文地質特性調查與分析類似案例的參考與應用。

關鍵字

裂隙岩體 ； 離散裂隙網絡模式(DFN) ； 代表性體積元素 ； 裂隙參數 ； 幾何參數特性 ； 水力參數試驗

並列摘要

Hydraulic models play the key roles for description of underground water flow and solute transport, and are also crucial for the development and application of water resources and underground. The natural rock include many discontinuities like crevasses, beddings, joints and schistosities, which cause the difficulty in simulation and analysis and even further difficulties of engineering design and construction resulting in its mechanical and hydraulic behaviors present heterogeneity and anisotropy. Therefore, how to get the hydrogeological characteristics of the site and select the appropriate hydraulic model to perform prediction analysis through the modest description of scale is the key point for hydrogeological study from conceptual model, description model towards hydraulics model and numerical model.
This study designs a hydrogeological testing well site and a series of fracture parameters investigation and hydraulic parameters tests are performed, so as to get the equivalent hydraulic conductivity of fractured rock mass based on the site hydrogeological characteristics described by the discrete fracture network model (DFN) .To thoroughly obtain the parameters required by the DFN mode, laboratory experiments are conducted to obtain the characteristics of mechanical and geometric parameters. Based on the discrete fracture parameters from outcrop investigation, in-situ hydraulic test and lab test, this study established the fracture network by two-dimensional fracture network model to evaluate the site hydraulic conductivity.
This research shows the site equivalent hydraulic conductivity obtained by different hydraulic test methods applied in siltstones with the difference exceeding two orders of magnitude and the dimensions range is from 10-5 to 10-7m/s .From single well hydraulic test results shows the maximum difference of hydraulic conductivity resolved by different fracture combinations drops from 10-5 to 10-9 m/s, exceeding four orders of magnitude, indicating that the fracture distribution significantly affects the site hydrogeological characteristics. This study utilize the discrete fracture network model to build the well sites after investigating the fracture surface parameters and further obtains the site hydraulic conductivity based on site hydrological tests, which is a feasible technique for the investigation of the hydrogeological characteristics of fracture rock mass.
The simulation results show that, based on the fracture parameters measured nearby the well site, the numbers of fractures taken from the simulated discrete fracture network are similar to field measured data in wells. The calculated hydraulic conductivity dimension is from 10-5 to 10-7 m/s, which is very close to the average dimension of site hydraulic test results. This study demonstrates that using the discrete fracture network model to think about hydrogeological model can provide the references and applications for similar cases of investigation and analysis on hydrogeological properties by investigating procedure of fracture rock parameters and permeation parameters and statistical analysis. The procedure includes the wells site building, in-situ test, laboratory experiments and related simulation analysis technologies.

並列關鍵字

fractured rock ； discrete fracture network ； REV ； fracture parameters ； geometric parameters ； hydraulic parameters tests

參考文獻

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