粗糙度与隙宽对单裂隙达西-非达西流演变规律的影响研究

Influence of Roughness and Fracture Width on the Transition from Darcy to Non-Darcy Behavior for Flow Through Rough Single Fracture

为研究岩石单裂隙的隙宽和粗糙度对达西-非达西流演变规律的影响,在已有研究的基础上,设计采用五种粗糙度轮廓与五种隙宽构建出25个粗糙单裂隙模型.粗糙度轮廓采用了Barton提出的被广泛使用的标准JRC曲线,取JRC范围为0~2,4~6,8~10,12~14和16~18,作为定量考虑粗糙度影响的变量;裂隙宽度采用1,2,3,4和5 mm作为定量考虑隙宽影响的变量.同时,采用CFD中广泛使用和认可的Fluent软件中的k-?模型,对单裂隙模型中的水流进行模拟.研究结果表明,在相同的流速下,粗糙度与隙宽的大小影响了非达西渗流比例,非达西渗流比例随着粗糙度增加而增大,随着隙宽的增加而减少;同时,随着粗糙度减少或者隙宽的增加,粗糙单裂隙中判断达西-非达西流演变的临界雷诺数也随之增大,进而拟合出粗糙单裂隙中JRC、隙宽与临界雷诺数的关系式.

In order to study the influence of the fracture width and roughness of single fracture on the Darcy-non-Darcy flow,this paper has designed five roughness and five fracture widths to construct 25 rough Single fracturemodel. The roughness profile in this paper uses the widely used standard JRC curve proposed by Barton,taking JRC=0-2,4-6,8-10,12-14 and 16-18 as variables for quantitative consideration of roughness;Width using 1,2,3,4 mm and 5 mm as a quantitative consideration of the impact of the fracture width variable. At the same time,thewater flow in the single fracture model is simulated by using the k-З model in Fluent software,which is widely usedand recognized in CFD. The results show that the ratio of roughness and fracture width affects the ratio of non-Darcy flow at the same flow rate,and the ratio of non-Darcy flow increases with the increase of roughness anddecreases with the increase of the fracture width. With the decrease of roughness or the increase of the fracturewidth,the critical Reynolds number of the Darcy-non-Darcy flow is also increased in the rough single fracture. Andthen the relationship among JRC,fracture width and critical Reynolds number in rough single fracture is fitted.