Influence Mechanism Of Geometric Properties On Flow Characteristics Of Cross Fracture

Bedrock fissures are widely distributed in nature,and bedrock fissures mainly exist in the form of a network in nature.Crossed fissures are the basic unit that constitutes a fissure network.The geometric properties of crossed fissures are also an important index that affects the hydraulic properties of fissure water.But how to explain and quantify has been a challenging problem in the field of bedrock hydrogeology.In this paper,Fluent6.3.26 simulation software is used as a tool to design a "herringbone" "one-in two-out" cross-fracture model.The inlet section is A,and the outflow sections are B and C.Among them,the B-fracture refers to the fissure.By changing the joint roughness coefficient JRC(Joint Roughness Coefficient),gap width,and cross angle of the C-fracture medium,the flow characteristics of the water flow in the cross-fracture medium under different geometric properties are analyzed,and the relevant parameters and The main research results and conclusions about the relationship between the changes of geometric attributes are as follows:(1)With the increase of the C joint fracture roughness coefficient(JRC),the increase of the gap width ratio,and the increase of the cross angle of the crack,the turbulent phenomenon of the branch crack C becomes larger and larger.(2)The V-J curve in the cross-fracture medium has a clear nonlinear relationship.The nonlinear relationship becomes more and more obvious as the crack joint roughness coefficient increases,the gap width and the cross angle increase.By calculating the inertia coefficient term ?,it is found that the value of ? increases with the increase of the crack roughness and cross angle;as the gap width increases,the inertia coefficient ? gradually decreases.(3)Through the q J fitting curve,it is found that there is a quadratic relationship between the hydraulic gradient and the flow rate;by defining the flow distribution rate,it is found that there is n=a Re2+b Re+c between the flow distribution rate n and Re Quadratic relationship.(4)With the change of roughness,gap width and cross angle,the local pressure drop of each branch crack at the cross of the cross crack shows an alternating size change;the friction resistance coefficient gradually decreases as the Reynolds number increases,In the end,it will gradually stabilize.The effect of different geometric attributes on the cross-fracture bias flow is gap width ratio>roughness>cross angle.