Non-linear flow behaviour of rough fractures having standard JRC profiles

Zoorabadi, Mahdi; Saydam, Serkan; Timms, Wendy; Hebblewhite, Bruce

doi:10.1016/j.ijrmms.2015.03.004

Cited by 59 publications

(22 citation statements)

References 17 publications

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“…The quadratic coefficient b decreases with the increase of microfracture aperture, whereas there is no obvious correlation between coefficient a and microfracture aperture. A similar experiment by Zoorabadi et al 26 reported that the coefficient b decreased with the increase of fracture aperture, which was consistent with the experimental results.…”

Section: The Variation Of Normal Deformation Of the Microfracture Undsupporting

confidence: 90%

Experimental study on seepage characteristics of microfracture with different aperture

Zhang

Qiao

et al. 2020

Sci Rep

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Exploring the flow mechanism of fluid in rock mass is important in solving the water inrush problems during tunnel excavation. However, it is difficult to obtain an undisturbed rock mass from the actual site conditions and study the flow mechanism of fluid through a fracture network composed of multiple single fractures. Therefore, a solution to simulate rock seepage using rock-like samples with single microfracture was presented in this paper. Water flow through microfracture was tested and the deformation of microfracture was recorded by quasi-distributed fiber Bragg grating (FBG) technology. Experimental data showed that Forchheimer's law and Izbash's law could well describe the nonlinear relationship between flow velocity and hydraulic gradient. The coefficient b in Forchheimer's equation decreased with the increase of microfracture aperture. A critical value of E = 0.8 was proposed to classify the nonlinear flow regime: weak turbulence (E < 0.8) and fully developed turbulence (E > 0.8).

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Section: The Variation Of Normal Deformation Of the Microfracture Undsupporting

confidence: 90%

Experimental study on seepage characteristics of microfracture with different aperture

Zhang

Qiao

et al. 2020

Sci Rep

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“…Zimmerman et al [16] found the phenomenon of Forchheimer flow in rough fracture when the Reynolds number is bigger than 20 for the first time by means of experiments and numerical method. Zoorabadi et al [17] carried out saturated seepage test on crack specimens with different roughness coefficients JRC and discussed the effects of Reynolds number and relative roughness on nonlinear seepage characteristics. With the rapid development of computer technology, the numerical simulation method has played an important role in considering the geometrical features of fracture surface and studying the seepage of jointed rock mass.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Seepage Properties of Jointed Rock‐Like Samples Based on 3D Printing Techniques

Tan

Wang

2020

Advances in Civil Engineering

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Sample making of fractured rock mass is a big problem in rock mechanical test. The specimens prepared by traditional rock core drilling have some disadvantages such as unclear internal structure and great difference in mechanical properties; while, the samples prepared by inserting and seaming method have some other disadvantages such as hard to control the attitude of precast-joints, low accuracy. A method for preparing fractured rock-like samples based on 3D printing technology is introduced in this paper, and the seepage characteristics of fractured rock-like samples is studied by seepage experiments. Firstly, the standard profile curves of 10 grades of joint roughness are digitized and 10 groups of 3D digital fracture models are established with different roughness and thickness (i.e., 1.5, 3.0, and 5.0 mm, respectively). 30 fracture inserts are produced by 3D printing technology. Then, rock-like specimens with through-filling fractures are poured with molds. Finally, the permeability tests of the prepared rock-like specimens are carried out to study the seepage characteristics of fractures with different roughness and gap widths under different confining pressures. The results show that 3D printing technology provides an effective way for production of complex crack samples in laboratory test and the comparative analysis of tests. The seepage characteristics of fractures are well studied. When the gap width is small, the permeability decreases with the increase of roughness, and the influence of roughness on fracture permeability decreases rapidly with the increase of confining pressure and gap width. The permeability of through-filling fractures with different roughness and gap width decreases with the increase of confining pressure. The relationship between confining pressure and fracture permeability can be described by the power function. 3D printing technology overcomes the shortcomings of traditional specimen preparation methods and greatly improves the precision of crack inserts. The jointed rock-like model established by the method revealed the influence of fracture characteristics on seepage flow very well.

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“…Geometry alterations related to shearing and surface roughness have resulted in an increase in the overall resistance [12]. Several geometric parameters, such as fractal dimensions [18], the high-order statistical parameters of the roughness height [19], the effective slope [20,21], the roughness decomposition [5], and the joint roughness coefficient (JRC) [22], have been used to represent the wall roughness and to better understand the effect of surface roughness on the fracture flow. However, the surface roughness alone is not sufficient to represent the influence of geometry alteration.…”

Section: Introductionmentioning

confidence: 99%

Effect of Shearing on Non-Darcian Fluid Flow Characteristics through Rough-Walled Fracture

Long

et al. 2020

Water

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The heterogeneous fracture geometry induced by the presence of roughness and shearing complicates the fracture flow. This paper presents a numerical investigation of the non-Darcian flow characteristics of rough-walled fractures during shear processes. A series of fracture flow simulations were performed on four types of fractures with different joint roughness coefficients (JRCs), and the different shear displacements were imitated by degrees of mismatch on two fracture surfaces. The results show that the disorder of fracture geometries and the increase in flow rate are the main causes for the emergence of an eddy flow region, which can significantly reduce the fracture conductivity and change the fracture flow from linear to nonlinear. The Forchheimer equation provides a good model for the nonlinear relationship between the hydraulic gradient and the flow rate in the fracture flow. When the shear displacement or JRC increased, the linear permeability coefficient kv decreased, while the nonlinear coefficient β increased. A three-parameter equation of β was used to examine the inertial effect induced by the fracture roughness JRC and the variation coefficient of aperture distribution σs/em. The critical Reynolds number was a combined effect of aperture, viscous permeability, and inertial resistance, assuming the flow becomes non-Darcian when the inertial part is greater than 10%.

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Non-linear flow behaviour of rough fractures having standard JRC profiles

Cited by 59 publications

References 17 publications

Experimental study on seepage characteristics of microfracture with different aperture

Experimental study on seepage characteristics of microfracture with different aperture

Experimental Study on Seepage Properties of Jointed Rock‐Like Samples Based on 3D Printing Techniques

Effect of Shearing on Non-Darcian Fluid Flow Characteristics through Rough-Walled Fracture

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