Experimental Study On Permeability Coefficient In Fractured Rock Mass Of Tunnel

Using Brazilian splitting test to generate single fracture, vertical cross fracture, to simulate tunnel limestone single, cross extensional fractures of tunnel rock, then to carry out the triaxial test research of the single fracture, vertical cross coupling of seepage and stress of surrounding rock, coefficient of permeability and fracture width, area, the relationship between the roughness coefficient of regular triaxial test on the rock multi-function testing machine, mainly studied the specimen axial compression, confining pressure and water pressure on the influence of the fissure permeability coefficient, fitting method is presented under different stress conditions of single fracture, vertical cross fracture permeability coefficient math formulas, and the relation curve of fracture area and permeability coefficient, experiments show that the following:(1)The fracture surface image processing method was adopted in test(Matlab image analysis-AutoCAD image processing) of fracture width measurement method is improved, the fracture width of accurate test data were obtained.(2)Homemade buttock meter fissure image is adopted in experiment, and compared with standard method for fracture roughness coefficient of roughness area is relatively better than the method of measurement is improved.(3)In under the condition of axial stress, water pressure constant confining pressure increases, the single fissure permeability and confining pressure meet have been relations, while vertical cross fracture permeability and confining pressure meet the logarithmic relationship.(4)Single fracture and vertical cross fracture, in the constant confining pressure, water pressure, axial stress, increase permeability coefficients and axial stress was positively than linear relationship; The axial stress caused by increasing sample radial drum effect is the dominant factors influencing the fracture permeability; When constant confining pressure, axial stress, fracture permeability and water pressure were positively than linear relationship. The fracture opening decreases with the increase of confining pressure, but the confining pressure increases to a certain degree, will gradually stabilized, this is because the confining pressure cannot make fracture closed completely, fissure seepage still exists, and the permeability coefficient is greater than the fractured rock mass permeability coefficient.(5)Single fracture or vertical cross fracture permeability coefficient and the area into n to the power relationship.(6)In a single fracture roughness coefficient > 9, vertical cross > 10 roughness coefficient, The relationship between permeability coefficient and fracture area by quadratic function transition to three functions.(7)Numerical fitting out of the permeability coefficient and single fracture roughness coefficient(≤9)and the function relation between face area.