文献类型：期刊文献

英文题名：A numerical approach for assessing effects of shear on equivalent permeability and nonlinear flow characteristics of 2-D fracture networks

作者：Liu Richeng[1];Li Bo[2,3];Jiang Yujing[4,5,6];Yu Liyuan[1]

机构：[1]China Univ Min & Technol, State Key Lab Geomech & Deep Underground Engn, Xuzhou 221116, Peoples R China;[2]Shaoxing Univ, Zhejiang Collaborat Innovat Ctr Prevent & Control, Shaoxing 312000, Peoples R China;[3]Shaoxing Univ, Ctr Rock Mech & Geohazards, Shaoxing 312000, Peoples R China;[4]Shandong Univ Sci & Technol, State Key Lab Min Disaster Prevent & Control Shan, Qingdao 266590, Peoples R China;[5]Shandong Univ Sci & Technol, Minist Sci & Technol, Qingdao 266590, Peoples R China;[6]Nagasaki Univ, Sch Engn, Nagasaki 8528521, Japan

年份：2018

卷号：111

起止页码：289

外文期刊名：ADVANCES IN WATER RESOURCES

收录：SCI-EXPANDED(收录号：WOS:000418592800020)、、EI(收录号：20174904486061)、Scopus(收录号：2-s2.0-85035345150)、WOS

基金：This study has been partially funded by National Natural Science Foundation of China, China (Grant Nos. 51609136, 51709260), National Science Foundation of Jiangsu Province, China (Grant No. BK20170276), and the Zhejiang Collaborative Innovation Center for Prevention and Control of Mountain Geological Hazards, China (Grant No. PCMGH-2016-Z-01).

语种：英文

外文关键词：Fracture network; Nonlinear flow; Shear; Navier-Stokes equations; Surface roughness; Aperture heterogeneity

外文摘要：Hydro-mechanical properties of rock fractures are core issues for many geoscience and geo-engineering practices. Previous experimental and numerical studies have revealed that shear processes could greatly enhance the permeability of single rock fractures, yet the shear effects on hydraulic properties of fractured rock masses have received little attention. In most previous fracture network models, single fractures are typically presumed to be formed by parallel plates and flow is presumed to obey the cubic law. However, related studies have suggested that the parallel plate model cannot realistically represent the surface characters of natural rock fractures, and the relationship between flow rate and pressure drop will no longer be linear at sufficiently large Reynolds numbers. In the present study, a numerical approach was established to assess the effects of shear on the hydraulic properties of 2-D discrete fracture networks (DFNs) in both linear and nonlinear regimes. DFNs considering fracture surface roughness and variation of aperture in space were generated using an originally developed code DFNGEN. Numerical simulations by solving Navier-Stokes equations were performed to simulate the fluid flow through these DFNs. A fracture that cuts through each model was sheared and by varying the shear and normal displacements, effects of shear on equivalent permeability and nonlinear flow characteristics of DFNs were estimated. The results show that the critical condition of quantifying the transition from a linear flow regime to a nonlinear flow regime is: 10(-4) < J < 10(-3), where J is the hydraulic gradient. When the fluid flow is in a linear regime (i. e., J < 10(-4)), the relative deviation of equivalent permeability induced by shear, delta(2), is linearly correlated with J with small variations, while for fluid flow in the nonlinear regime (J > 10(-3)), delta(2) is nonlinearly correlated with J. A shear process would reduce the equivalent permeability significantly in the orientation perpendicular to the sheared fracture as much as 53.86% when J = 1, shear displacement D-s = 7 mm, and normal displacement D-n = 1 mm. By fitting the calculated results, the mathematical expression for delta(2) is established to help choose proper governing equations when solving fluid flow problems in fracture networks.