本研究主要以計算流體力學數值軟體PHOENICS及單一裂隙定水頭試驗，探討節理內寬中不同內寬寬度及粗糙度對水流的影響，數值模式中採用二維變動平行板之物理模型來代表節理內寬空間狀況，進而模擬其水流情形，並與前人提出之內寬評估之各不同經驗模式(Patir and Cheng模式、Zimmerman模式、Sisavath模式以及Liu模式)相比較，提出各模式之適用性。另外，利用機械工業精密量測提出之粗糙度參數(JRC)來計算粗糙狀況，並進行水力內寬試驗以求當量水力內寬值，代入各模式中得到不同力學內寬值，進行不同模式比較。

結果顯示，力學內寬與節理粗糙標準偏差之比值與導水性之關係可分為三部份，當力學內寬與節理粗糙標準偏差之比值大於8.0時，各模式皆趨近於一平穩值，代表粗糙幾何狀況較平緩，此時利用平行板模式來模擬節理面水流狀況有良好的效果；當力學內寬與節理粗糙標準偏差之比值介於3.0至8.0時，各模式因假設條件及理論不同而有差異，但仍能適切描述此區導水性與力學內寬與節理粗糙標準偏差之關係，可因為需求之不同，而選擇不同模式來解決問題；當力學內寬與節理粗糙標準偏差之比值小於3.0時，各模式差異甚大，無法觀察出此區之導水性情形，因此不建議使用各模式來探討。水力內寬試驗結果顯示，內寬經驗模式可根據考慮規模效應與否，而分為兩大類，即有考慮規模效應與無考慮規模效應，依據解決問題之不同，而使用不同模式來推估。

The main purpose of this paper is to evaluate the effect of flow in fractures. The numerical simulation (PHOENIS software) is performed under the constant head flow through single aperture experiment at various aperture roughness conditions. The empirical models of apertures (Patir and Cheng model, Zimmerman model, Sisavath model, and Liu model) are presented in order to compare the variation and to describe suitable conditions from different models. In addition, this study adopts the parameter of roughness from precise measurement of mechanical industry. The equivalent hydraulic apertures can be calculated from the results of experiment, and then we can obtain different mechanical apertures by using different models with equivalent hydraulic apertures.

When 2-D non-constant parallel plate model is used to simulate the flow behavior of space condition of apertures and compared with the empirical models, it indicates that the relationship of the ratio of the mean aperture to its standard deviation and conductivity of fluid flow can be divided into three parts. Firstly, when the ratio is over 8.0, each empirical model becomes gradually stationary, it indicates that the roughness is smooth and we use parallel plate model to simulate the fluid flow in apertures can obtain fine results. Secondly, when the ratio is between 3.0 and 8.0, different models simulate different conditions because each model has different hypothetical conditions and theory basis. It still can describe well the relationship between the conductivity, the mean aperture, and the standard deviation. Finally, when the ratio is lower than the value of 3.0, each model has quite different results, we can not observe the conductivity of fluid flow in this part. Therefore, this study does not provide any suggestions for using each empirical model in third part. In the apertures experiment results indicate that according to scale effect, the empirical models can be divided into two sections. We can use different models to evaluate apertures at different conditions.

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