Experimental Study And Numerical Simulation Analysis Of Seepage In Fractured Rock-like Mass

Rock masses usually contain fractures due to perturbations resulting from geological movement and human activities.and the rock fractures are the storage space and seepage channel of groundwater.The movement of groundwater within the fissures is the main cause of engineering accidents,Therefore,it is a hot topic to study the seepage flow of fractured rock mass.In this paper,fractured rock mass is taken as the main research object.The seepage tests of the influence of confining pressure,water pressure and fracture width on seepage flow are carried out.The mathematical model is established by ABAQUS finite element software,Analysis of seepage characteristics under different pore pressures and inclined angle fractures.The main research contents and results are as follows:(1)According to the ratio test,the specimens were prepared,the RLW-2000 microcomputer controlled rock servo triaxial rheological machine was used to conduct the triaxial compression test,to obtain the physical and elastic parameters of the specimens.At the same time,the stress-strain curves and peak strength curves under different confining pressures were obtained.It is found that:the peak strength and residual strength increase with the increase of confining pressure.(2)Using the above-mentioned test device,to conduct the loading and unloading seepage test for specimens with different single fracture widths and parallel fracture,The relationship between water pressure,confining pressure,fracture width and seepage flow rate was analyzed respectively.Through the experimental research,it is found that:Under the same axial pressure,hydraulic pressure and fracture width,the seepage flow decreases with the increase of confining pressure,However,when confining pressure increases to a certain extent the decreases rate of seepage flow slows down;At the same time,the seepage flow during confining pressure unloading tends to be smaller than in the loaded state.However,just changed the water pressure,the seepage flow increases with the increase of hydraulic pressure;what's more,under the same conditions,the seepage flow rate under water pressure unloading is larger than that in the loading.When axial pressure,confining pressure and water pressure remain unchanged,the seepage flow increases with the increase of fracture width;When the water pressure is small,the increase of fracture width will change the seepage flow greatly;When the water pressure is greater than 0.4×106Pa,the water pressure is the main factor affecting the seepage flow.With the increase of fracture width,the seepage flow increment begins to decrease.In the case where the axial pressure and confining pressure remain unchanged,When the water pressure is lwss than 0.3×106Pa,the seepage flow of parallel fracture is less than that of combined fracture obviously;And continue to increase the water pressure,the difference of seepage flow between parallel fracture and combined fracture begins to decrease.(3)By finite element method with software ABAQUS,the numerical simulation of prefabricated through single crack specimens with the crack width of 0.2 mm is carried out,analysis of seepage change under different water pressures.The numerical analysis results are compared with the experimental results under the same conditions to verify the accuracy of the numerical simulation.At the same time,Numerical simulation study on permeability properties of in different pore pressures and crack angles,from the results of numerical analysis:The seepage flow and seepage velocity increase with the increase of pore pressure.,however,it tends to decrease with the increase of fracture angle.with the increase of inclination angle,there is a decreasing trend;Pore pressure is mainly distributed in the vicinity of fracture structure plane,and the pore pressure gradually decreases from top to bottom along the angle of the fracture;The maximum seepage velocity increases with the increase of water pressure,and decreases with the increase of inclination angle.Near the fracture plane,the stress in the X and Z directions decreases with the increase of pore pressure,And with the increase of the distance from the loading pore pressure,the value of stress decreases gradually.