Estimating joint roughness coefficients

Tse, Rex.; Crudën, D. M.

doi:10.1016/0148-9062(79)90241-9

Cited by 781 publications

(240 citation statements)

References 8 publications

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“…The surface roughness of faults is generally greater than that of bedding planes, with average values of asperity heights of 1.4 mm and 0.5 mm, respectively (CLA index) [Tse and Cruden, 1979]. Compared to laboratory observations of flow channeling in rough fractures, a fracture with a CLA index of 1.4 mm contains highly conductive preferential flow channels [Cappa et al, 2005].…”

Section: Fracture Wall Morphology Characterizationmentioning

confidence: 91%

Estimation of fracture flow parameters through numerical analysis of hydromechanical pressure pulses

Cappa

Guglielmi

Rutqvist

et al. 2008

Water Resources Research

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[1] The flow parameters of a natural fracture were estimated by modeling in situ pressure pulses. The pulses were generated in two horizontal boreholes spaced 1 m apart vertically and intersecting a near-vertical highly permeable fracture located within a shallow-fractured carbonate reservoir. Fracture hydromechanical response was monitored using specialized fiber-optic borehole equipment that could simultaneously measure fluid pressure and fracture displacements. Measurements indicated a significant time lag between the pressure peak at the injection point and the one at the second measuring point, located 1 m away. The pressure pulse dilated and contracted the fracture. Field data were analyzed through hydraulic and coupled hydromechanical simulations using different governing flow laws. In matching the time lag between the pressure peaks at the two measuring points, our hydraulic models indicated that (1) flow was channeled in the fracture, (2) the hydraulic conductivity tensor was highly anisotropic, and (3) the radius of pulse influence was asymmetric in that the pulse traveled faster vertically than horizontally. Moreover, our parametric study demonstrated that the fluid pressure diffusion through the fracture was quite sensitive to the spacing and orientation of channels, hydraulic aperture, storativity, and hydraulic conductivity. Comparison between hydraulic and hydromechanical models showed that the deformation significantly affected fracture permeability and storativity and, consequently, the fluid pressure propagation, suggesting that the simultaneous measurements of pressure and mechanical displacement signals could substantially improve the interpretation of pulse tests during reservoir characterization.

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Section: Fracture Wall Morphology Characterizationmentioning

confidence: 91%

Estimation of fracture flow parameters through numerical analysis of hydromechanical pressure pulses

Cappa

Guglielmi

Rutqvist

et al. 2008

Water Resources Research

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“…In total, the JRC values of 5 2D profiles are calculated and their average value is regarded as the JRC of a 3D single fracture. The JRC values of all 2D profiles were estimated based on the values of 2 using (13) proposed by Tse and Cruden [39]. Here, JRC is a dimensionless index ranging from 1 to 20 [40], which has been widely accepted in the field of rock mechanics and rock engineering [22,41].…”

Section: Rock Fracture Specimen Preparationmentioning

confidence: 99%

Experimental Study on Stress-Dependent Nonlinear Flow Behavior and Normalized Transmissivity of Real Rock Fracture Networks

et al. 2018

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The mechanism and quantitative descriptions of nonlinear fluid flow through rock fractures are difficult issues of high concern in underground engineering fields. In order to study the effects of fracture geometry and loading conditions on nonlinear flow properties and normalized transmissivity through fracture networks, stress-dependent fluid flow tests were conducted on real rock fracture networks with different number of intersections (1, 4, 7, and 12) and subjected to various applied boundary loads (7, 14, 21, 28, and 35 kN). For all cases, the inlet hydraulic pressures ranged from 0 to 0.6 MPa. The test results show that Forchheimer's law provides an excellent description of the nonlinear fluid flow in fracture networks. The linear coefficient and nonlinear coefficient in Forchheimer's law = + 2 generally decrease with the number of intersections but increase with the boundary load. The relationships between and can be well fitted with a power function. A nonlinear effect factor = 2 /( + 2 ) was used to quantitatively characterize the nonlinear behaviors of fluid flow through fracture networks. By defining a critical value of = 10%, the critical hydraulic gradient was calculated. The critical hydraulic gradient decreases with the number of intersections due to richer flowing paths but increases with the boundary load due to fracture closure. The transmissivity of fracture networks decreases with the hydraulic gradient, and the variation process can be estimated using an exponential function. A mathematical expression / 0 = 1 − exp(− −0.45 ) for decreased normalized transmissivity / 0 against the hydraulic gradient was established. When the hydraulic gradient is small, / 0 holds a constant value of 1.0. With increasing hydraulic gradient, the reduction rate of / 0 first increases and then decreases. The equivalent permeability of fracture networks decreases with the applied boundary load, and permeability changes at low load levels are more sensitive.

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“…The magnitude of the crack surface roughness was calculated according to JRC values [6,7], which are used as a joint surface roughness index in rock mechanics, after measuring the roughness at intervals of 0.5 mm by means of a laser displacement gauge. A large JRC value indicates a rough surface.…”

Section: Crack Surface Roughness Obtained At Actual Tunnelmentioning

confidence: 99%