Experimental Study On Permeability Characteristics Of Cross Fractured Rock Mass

This paper takes the limestone as the research object, I mainly study cross fractured rock and sand filling of fractured rock the influences of confining pressure, axial pressure, seepage pressure and fracture surface roughness of the structure, fracture area and gap width, filling sand diameter, filling crack width and area and other factors on the permeability coefficient. Main results are:(1)The limestone after split, using image processing method to deal with the fracture surface and make the fracture picture gray processing, binarization processing, threshold processing by using MATLAB software,then import proportion programming according to the proportional relationship obtained fracture area and fracture width,graphics processing is applied to the crack width measurement, crack width and the crack area measurement more accurate, enable penetration test data processing is more accurate.(2)To cross fracture rock sample, the axial compression stability, inlet end under the constant water pressure and vertical cross and cross sample permeability more diminishing with the increase of confining pressure a logarithmic relationship; Constant confining pressure is fixed, inlet pressure, vertical cross fracture permeability coefficient decreasing with the increase of axial compression exponential relationship, while cross fracture permeability coefficient with the increase of axial compression linearly decreasing relationship; When the axial compression, confining pressure are fixed, the permeability coefficient and seepage water pressure increasing is a linear relationship.(3)For sand filling a single fracture rock specimen when axial pressure is stable and under constant pressure inlet side, the permeability coefficient decreases with the increase of confining pressure; under constant confining pressure, water inlet constant pressure conditions, with the permeability coefficient axial pressure decreases; gap width under the same conditions, the smaller the particle size of the filling sand filling smaller cracks rock sample permeability coefficient corresponding to, the greater the contrary; permeability coefficient of filling sand thickness on a single fracture rock mass significantly under uniaxial compressive and confining pressure, the greater the thickness of the filling, filling sand single fissured rock permeability coefficient greater.(4)Vertical cross fractured rock sample permeability and fracture area is a function of the cube or hypercube, roughness coefficient and permeability of less than 13 cubic function relationship was fractured area, roughness coefficient value is greater than 13,permeability and fracture permeability area was four function.(5) Vertical cross-fractured rock specimen seepage test, through data analysis and using least square fitting method, fit the permeability coefficient and axial pressure confining pressure function formula, permeability coefficient and JRC, fractured area function formula.(6)Filling sand single fracture rock sample permeability coefficient with increasing fracture area increases, a quadratic function relationship between the two.