Experimental Investigation of Nonlinear Flow Characteristics of Real Rock Joints under Different Contact Conditions

Xia, Caichu; Qian, Xin; Lin, Peng; Xiao, Weimin; Gui, Yan

doi:10.1061/(asce)hy.1943-7900.0001238

Cited by 57 publications

(28 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This variation of fracture void space during shear can also change the nonlinear flow properties of fluid such as the critical Reynolds number Re , which is used for characterizing the onset of nonlinear flow. Xia et al [85] conducted laboratory experiments on three artificial rock joints having natural joint surface characteristics to investigate the nonlinear flow behaviors under different shear displacements. The cylindrical specimens that were cored from marble blocks taken from the construction site of Jin-Ping-II Hydropower Station in China have a diameter of 50 mm and a length of 100 mm.…”

Section: Effect Of Shear Displacementmentioning

confidence: 99%

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Jiang

2017

Geofluids

View full text Add to dashboard Cite

Selecting appropriate governing equations for fluid flow in fractured rock masses is of special importance for estimating the permeability of rock fracture networks. When the flow velocity is small, the flow is in the linear regime and obeys the cubic law, whereas when the flow velocity is large, the flow is in the nonlinear regime and should be simulated by solving the complex NavierStokes equations. The critical conditions such as critical Reynolds number and critical hydraulic gradient are commonly defined in the previous works to quantify the onset of nonlinear fluid flow. This study reviews the simplifications of governing equations from the Navier-Stokes equations, Stokes equation, and Reynold equation to the cubic law and reviews the evolutions of critical Reynolds number and critical hydraulic gradient for fluid flow in rock fractures and fracture networks, considering the influences of shear displacement, normal stress and/or confining pressure, fracture surface roughness, aperture, and number of intersections. This review provides a reference for the engineers and hydrogeologists especially the beginners to thoroughly understand the nonlinear flow regimes/mechanisms within complex fractured rock masses.

show abstract

Section: Effect Of Shear Displacementmentioning

confidence: 99%

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Jiang

2017

Geofluids

View full text Add to dashboard Cite

show abstract

“…As the Re increases to a relatively large value, the fluid flow enters the nonlinear flow zone in which the increase in discharge is smaller than the proportional increase in pressure gradient (

\nabla P

). To describe the nonlinear relation between

\nabla P

and Q , Forchheimer equation is the most extensively adopted method, in which the

\nabla P

is a quadratic function of the Q , as follows:

- \nabla P = a Q + b Q^{2}

a = \frac{μ}{T_{0}} = \frac{12 μ}{w e_{h}^{3}}, b = \frac{α ρ}{w^{2} e_{h}^{2}}

where a and b are coefficients that represent the pressure drop caused by linear and nonlinear effects, respectively.

α

is the non‐Darcy coefficient.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…The Re is defined as the ratio of inertial force to viscous force, which is commonly used to predict the termination of linear flow and onset of nonlinear flow behavior, written as

R e = \frac{ρ Q}{μ w}

…”

Section: Theoretical Backgroundmentioning

confidence: 99%

See 1 more Smart Citation

Effect of shearing on hydraulic properties of rough‐walled fractures under different boundary conditions

Wang

Jiang

Luan

et al. 2019

Energy Science & Engineering

View full text Add to dashboard Cite

This study experimentally investigated nonlinear flow characteristics of rough‐walled fractures during shear process under different boundary conditions, using the servo‐controlled shear‐flow apparatus. A series of shear‐flow tests were conducted on two types of rough fractures with different shear displacements under various boundary conditions. The effects of shear process, fracture surface roughness, boundary normal stiffness, and initial normal stress on nonlinear flow behaviors are analyzed. The results show that Forchheimer equation provides a good description of the nonlinear relationship between flow rate and pressure gradient in rough‐walled fractures. The linear and nonlinear coefficients decrease by 1‐2 and 2‐3 orders of magnitude during shear, respectively. Both the mechanical aperture and the hydraulic aperture increase with increasing shear displacement. The mechanical aperture is always larger than the hydraulic aperture, and their difference gradually increases with the increment of shear displacement. The contact area ratio exhibits a fast decrease as shear displacement ranges between 1 and 3 mm and then decreases gradually with the decreasing rate generally diminishes. With the increase in shear displacement, the critical Reynolds number shows an increasing trend. The critical Reynolds number is in range 3.22‐35.41 for fracture G1 and 1.23‐12.35 for fracture G3. As the boundary normal stiffness and initial normal stress increase, the critical Reynolds number decreases.

show abstract

“…To quantitatively estimate the nonlinearity of fluids flowing through the fracture networks, a nonlinear effect factor was introduced to determine the fluid flow regime [1,35,36]. It can be presented by…”

Section: Geofluidsmentioning

confidence: 99%

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

et al. 2018

View full text Add to dashboard Cite

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.

show abstract

Experimental Investigation of Nonlinear Flow Characteristics of Real Rock Joints under Different Contact Conditions

Cited by 57 publications

References 47 publications

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Effect of shearing on hydraulic properties of rough‐walled fractures under different boundary conditions

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

Contact Info

Product

Resources

About