Laboratory investigation of nonlinear flow characteristics in rough fractures during shear process

Guan, Rong; Yang, Jie; Cheng, Long; Zhou, Chuangbing

doi:10.1016/j.jhydrol.2016.08.043

Cited by 150 publications

(51 citation statements)

References 49 publications

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“…This variation trend is similar to that (with = 1.0 or 5.0 MPa) reported in Javadi et al [92]. As an example, when = 1.0 MPa, Re that corresponds to a small in the work of Javadi et al [92] is much smaller than that in the work of Rong et al [104]; however when is relatively large, Re in the work of Javadi et al [92] is approximately 2.0∼2.5 times that in the work of Rong et al [104]. The differences of Re evolution are dependent on fracture's morphology such as mean JRC.…”

Section: Effect Of Shear Displacementsupporting

confidence: 89%

“…They reported that Re for the samples G1∼G4 and S1∼S2 varies in the ranges 0.075∼ 9.243, 0.120∼4.467, 0.160∼5.108, 0.039∼4.509, 0.191∼4.090, and 0.026∼2.976, respectively. The results of Rong et al [104] as reported in Section 3.1 show that when = 0 mm, Re steadily decreases, presenting the same trend with the sample G1 in Figure 12. However, for samples under shear with > 0 mm, with the increment of confining pressure, Re firstly increases and then decreases as shown in Figure 13, presenting the same trends with most of the samples in Figure 12.…”

Section: Effects Of Normal Stress And/or Confining Pressuresupporting

confidence: 68%

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

Jiang

2017

Geofluids

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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.

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Section: Effect Of Shear Displacementsupporting

confidence: 89%

Section: Effects Of Normal Stress And/or Confining Pressuresupporting

confidence: 68%

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

Jiang

2017

Geofluids

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“…In view of the fact that the variations of linear and nonlinear coefficients and against and are very similar, as a function of was analyzed [29], as plotted in Figure 7(e). The experimental data can be fitted very well using the following empirical function: = 7.899 × 10 6 0.766 .…”

Section: Test Results and Discussionmentioning

confidence: 99%

“…For engineering purposes, a critical value of = 10% has been defined as the critical condition for onset of flow nonlinearity in fracture networks, where the nonlinear effect can be appreciable and cannot be neglected [23,24,29].…”

Section: Geofluidsmentioning

confidence: 99%

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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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A comprehensive review of experimental studies on shear behavior of bolted rock joints with varying rock joint and bolt parameters and normal stress

Zhou,

Lang,

Huang

et al. 2024

Deep Underground Science and Engineering

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The shear characteristics of bolted rock joints are crucial for the stability of tunneling and mining, particularly in deep underground engineering, where rock bolt materials are exposed to high stress, water pressure, and engineering disturbance. However, due to the complex interaction between bolted rock joints and various geological contexts, many challenges and unsolved problems arise. Therefore, more investigation is needed to understand the shear performance of bolted joints in the field of deep underground engineering. This study presents a comprehensive review of research findings on the responses of bolted joints subjected to shearing under different conditions. As is revealed, the average shear strength of bolted rock joints increases linearly with the normal stress and increases with the compressive strength of rock until it reaches a stable value. The joint roughness coefficient (JRC) affects the contact area, friction force, shear strength, bending angle, and axial force of bolted rock joints. A mathematical function is proposed to model the relationship between JRC, normal load, and shear strength. The normal stress level also influences the deformation model, load‐carrying capacity, and energy absorption ratio of bolts within bolted rock joints, and can be effectively characterized by a two‐phase exponential equation. Additionally, the angle of the bolts affects the ratio of tensile and shear strength of the bolts, as well as the mechanical behavior of both bolted rock joints and surrounding rock, which favors smaller angles. This comprehensive review of experimental data on the shear behavior of bolted rock joints offers valuable theoretical insights for the development of advanced shear devices and further pertinent investigations.

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Laboratory investigation of nonlinear flow characteristics in rough fractures during shear process

Cited by 150 publications

References 49 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

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

A comprehensive review of experimental studies on shear behavior of bolted rock joints with varying rock joint and bolt parameters and normal stress

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