三維水力破裂試驗顆粒流模擬技術開發

Three-Dimensional Hydraulic Fracture Test Simulation using Particle Flow Code

黃宥傑(You-Jie Huang)

指導教授 ： 王泰典

共同指導教授 ： 鄭富書(Fu-Shu Jeng)

國立臺灣大學/工學院/土木工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202103494

摘要

現地應力為地球科學、大地工程、資源工程等跨領域高度關注的資訊，不僅反映地殼受力狀況，提供地震災害研究與預測的依據，更影響地下隧道、坑室工程開挖穩定與安全，對於地球資源的開發或是廢棄物的地下存放等潛在應用，現地應力影響裂隙岩體的水力特性，因而成為近期大地資訊調查的重要課題，其中在水力破裂則為場址尺度調查現地應力常用的技術，除了鑽孔、封塞、灌注等相關技術，其調查現地應力的精準性建立在許多有關岩體條件的假設上，包括岩石材料的異向、異質性、鑽孔周圍是否存在裂隙、孔隙等，皆影響調查結果的闡釋與評估。
本研究旨在研發岩石三維水力破裂數值模擬技術，可以模擬水力破裂試驗過程注水壓力、流量曲線、岩石破裂過程，以及其受到現地應力的影響；據以探討水力破裂試驗應用於現地應力調查時受到周圍裂隙、孔隙存在以及岩質差異的影響，以為後續提出試驗結果的修正方式。本研究中數值模擬軟體為利用離散元素法(Discrete Element Method)為基礎的顆粒流軟體(Particle Flow Code)進行模擬技術的開發，物理模型試驗延續童舒暘(2020)的流程通過改變水泥砂漿配比提高滲透性進行實驗室水力破裂試驗。
研究中所開發的Neighbor Method能夠考量滲流以及破裂裂縫生衍情形並進行水力破裂試驗水壓力曲線中破裂水壓力與再開水壓力的模擬，而模擬結果中破裂水壓力隨著圍壓增加而提升以及模型中隨著軸差應力的變化裂隙有一定的規律兩者符合物理現象。

關鍵字

水力破裂試驗 ； 實驗室內水力破裂試驗 ； 顆粒流軟體 ； 數值模擬 ； 現地應力 ； 裂縫生衍

並列摘要

Current in-situ stress is information of high concern across fields such as geosciences, geotechnical engineering, and resource engineering. It not only reflects the stress status of the earth’s crust, but also provides a basis for earthquake disaster research and prediction. It also affects the stability and safety of the excavation of underground tunnels and pits. Potential applications such as the development of earth resources or underground storage of wastes. The in-situ stress affects the hydraulic characteristics of fractured rock masses, which has become an important subject of recent geodetic information surveys. All affect the interpretation and evaluation of survey results.
The purpose of this research is to develop three-dimensional rock hydraulic fracture numerical simulation technology, which can simulate the water injection pressure, flow curve, rock fracture process, and the influence of in-situ stress in the hydraulic fracture test process; it is used to discuss the impact of hydraulic fracture test when applied to in-situ stress investigation. The influence of the existence of surrounding fissures, pores, and differences in rock quality, as a way to modify the test results later。
The Neighbor Method developed in the research can consider the seepage and the occurrence of rupture cracks and simulate the rupture water pressure and reboiled water pressure in the hydraulic rupture test water pressure curve, and the simulation results
The break-down pressure increases with the increase of confining pressure and the fractures have a certain law with the change of the axial differential stress in the model, which are in line with physical phenomena.

並列關鍵字

Hydraulic fracture test ； Hydraulic fracture test in laboratory ； Particle Flow Code ； Numerical simulation ； In-situ stress ； fracture generation

參考文獻

1. Adachi, J., et al. (2007). "Computer simulation of hydraulic fractures." International Journal of Rock Mechanics and Mining Sciences 44(5): 739-757.

2. Al-Busaidi, A. (2005). "Distinct element modeling of hydraulically fractured Lac du Bonnet granite." Journal of Geophysical Research 110(B6).

3. Allmendinger, R. W. (1998). "Inverse and forward numerical modeling of trishear fault-propagation folds." Tectonics 17(4): 640-656.

4. Asadollahi, P. and F. Tonon (2010). "Constitutive model for rock fractures: Revisiting Barton's empirical model." Engineering Geology 113(1-4): 11-32.

5. Barton, C. A., et al. (1995). "Fluid flow along potentially active faults in crystalline rock." Geology 23(8): 683-686.