Research Of Mechanics And Seepage Properties Of Sandstone Similar Material Of Joint During Shear

Fracturs are the main seepage channel in rock mass and are vulnerable to deformation and destruction in complex state of stress,so it is import ant for the safety and operation of engineeringto confirm and investigate the mechanics and seepage properties of fracture in complex strained condition accurately.In this study,sandstone which in shallow depth was taken as the research object,plaster was taken as the similar material,Coupled shear-flow tests were proceeded on different normal stress and hydraulic pressure of single fracture.Dilatany empirical formula which after peak shear displacement was establiished to analyze shear strength with Patton formula during shear.Radial flow cubic law was deduced,3-D simulation models were established by COMSOL,the differences of cubic law and expcrimental values were analyzed by testing phenomenon and simulation results.The cubic law was moddified by the empirical relation of mechanical aperture and hydrailic aperture under high hydraulic pressure.The non-linear pbenomena of flow fluid was analyzed by Forcheimer and Lzbash law during shear from a macro perspective.The main resets and conclusions were shown as follows:(1)The physical and mechanics parameters and physical dimenisiorn were confirmed by ?theorem,selected sandstone and experiment environment.The result showen that,Plaster was a good type of similar material for stand stone for laborator test.(2)There was a new thinking for confirrming shear strength of fraecture at random ranshdom shear displacement.In this paper,the deformation of fracture was reflected by shear dilatancy angle,cut off by peak shear displacement,the dilatancy empirical formula was established after peak shear displacenment.The shear strength empirical formula was established by dilatancy ampiricalformula and Patton formula.The restults shown that the shear strength in any moment can be predictcted by shear strength empirical formula and Patton formula.The volume and accumulation from of infilling materials had strong influence in the displacement and shear stress of fracture.(3)A new radial flow cubic law was deduced which was more close to experimental results,and the differences between of experimental value and cubic law was illuminated by experimental results and simulation models,which were bifurcated when the joint of fracture were broken.The results shown that the differences were caused by complex geometry of joint,infilling materials anisotropy of flow and nonlinearity of flow caused by high hydraulic pressure.The empirical formula of mechanical aperture and hydraulic aperture was established by considering the evolution of aperture and nonlinearity of flow caused by complex geometry of joint and high hydraulic pressure.Hydraulic conductivity increased greatly during shear because of the increase of aperture.Hydraulic conductivity was decreased by increasing normal stress,because normal stress had strong influence in aperture and geometry of joint.Hydraulic conductivity was decreased by increasing hydraulic pressure because of the nonlinearity of flow.(4)The evolution of the nonlinearity of flow during shear was analyzed by Forchheimer law and Lzbash law,the empirical formula of critical Reynolds number and shear displacement.The results shown that Forchheimer law and Lzbash law can explore the nonlinear variation of fluid flow during shear effectively from a macro perspective on different high hydraulic pressure,the nonlinear effect of fluid flow was depressed during shear because the evolution of aperture and geometry of joint during shear.