Prediction of water inflow into underground excavations in fractured rocks using a 3D discrete fracture network (DFN) model

Karimzade, Ebrahim; Sharifzadeh, Mostafa; Zarei, H.; Shahriar, K.; Seifabad, Masoud Cheraghi

doi:10.1007/s12517-017-2987-z

Cited by 22 publications

(6 citation statements)

References 38 publications

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“…The flow channels are explicitly demonstrated by the flow vector in Figure 13. Only some of the fractures contribute to the fluid flow, consistent with the observation in the previous reference [26]. The highest fluid flow rate is found at the junction of the fracture and the bottom slab, at approximately 0.0015 m/s, an increase of approximately four orders of magnitude compared to the absence of the fracture.…”

Section: Numerical Resultssupporting

confidence: 90%

“…Numerical models for water inflow in tunnel construction can be categorized into three main categories: the continuous uniform method [22][23][24], the discrete fracture network (DFN) [25,26], and the equivalent discrete fracture network (EDFN) [27,28]. The continuous medium approach is commonly used to study water seepage in formations with homogeneous properties, where the properties of a porous medium, including many solid particles and pores, are homogenized and quantified within a representative unit volume [29].…”

Section: Introductionmentioning

confidence: 99%

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A New Hydro-Mechanical Coupling Numerical Model for Predicting Water Inflow in Karst Tunnels Considering Deformable Fracture

Li,

Liao

et al. 2023

Sustainability

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The accurate prediction of groundwater inflow in tunnels in karst regions has been a difficult problem to overcome for a long time. This study proposes an equivalent fracture model that takes into account unsaturated seepage and fracture deformation to predict tunnel water inflow, which is constructed based on the TOUGH-FLAC3D framework. The proposed model with complete failure mechanisms of fracture, including shear failure and tensile failure, was applied to predict the water inflow of the Jianxing Tunnel in Guizhou Province to verify its effectiveness. The results indicate that the proposed numerical model was found to be comparable to on-site observations in predicting inflow rate. The inflow rate in a fractured network reaches a steady state faster than that in a non-fractured network. There is a significant difference of 100 times between the highest transient rate and the stable rate between the fracture network and the non-fractured model. The excavation-induced stress redistribution resulted in slip fracture occurring within a distance of approximately 8.2 m from the tunnel wall, which can increase the fracture width and in turn increases the amount of water flowing into the tunnel by about 50%. In addition, this paper also analyzes the impact of the factors of fracture density, incline angle, stress anisotropy, and initial fracture width on the inflow rate during tunnel construction. The study emphasizes the significance of considering deformable fractures and provides valuable insights for improving numerical tools for inflow prediction during tunnel construction.

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Section: Numerical Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

A New Hydro-Mechanical Coupling Numerical Model for Predicting Water Inflow in Karst Tunnels Considering Deformable Fracture

Li,

Liao

et al. 2023

Sustainability

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“…Therefore, the rock mass is composed of a matrix and fractures, as shown in Figure 1. After a long period of evolution, the discontinuous fractures are connected with each other, forming a complex network (Karimzade et al, 2017; Kim et al, 2007; Lokhande et al, 2015). The natural fractures not only determine the integrity of rock mass but also influence the mechanical properties.…”

Section: Mining‐induced Fracture Distributionmentioning

confidence: 99%

Fracture distribution in overburden strata induced by underground mining

Yao

Wang

Liu

et al. 2022

Deep Underground Science and Engineering

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Coal-mining activities give rise to a series of ecological environmental problems, such as ground settlement and groundwater pollution. In fact, they are mainly caused by mining-induced fractures. Hence, it is necessary to study the mining-induced fracture distribution to identify the behavior of rock mass movement. However, the fractures in overburden strata cannot be directly measured owing to the special condition. Therefore, the majority of previous studies are based on experiments or experience. For this reason, this study first used a discrete element method to simulate the shape of mining-induced fractures in overburden strata. Then, a geophysical tool of transient electromagnetic method (TEM) was used to investigate the mining-induced fracture distribution. Based on the low-resistivity anomaly area, the water-rich area in overburden strata was analyzed to be mainly caused by fracture seepage. Through the mutual authentication between numerical simulation and TEM results, the mining-induced fractures in overburden strata were explored. This study can enhance the understanding of mining-induced fracture distribution on the one hand and guarantee the coal mining safety on the other, thus guiding the coordinated development between coal mining and environmental protection.

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“…After obtaining the fracture location, two angles (i.e., dip and strike angles) and two edges (i.e., height and length) are then required to specify these fractures completely. Here we use a lognormal distribution and a Fisher distribution to generate the angles and the edges, respectively (Karimzade et al, ):

L = \exp ()(, μ_{l} + l σ_{l})

θ = acos ()(, \frac{\ln ()(, 1 - R_{U})}{K} + 1)

where L is the length of the fracture edge; l is a random number generated from a standard normal distribution; μ l and σ l are the mean and the standard deviation of standard normal distribution, respectively; θ is the dip or strike angle; R U is a random number generated from a uniform distribution between 0 and 1; and K is the Fisher constant. Another significant parameter is the fracture aperture, which may be described with a lognormal distribution.…”

Section: Methodsmentioning

confidence: 99%

“…Here we use a lognormal distribution and a Fisher distribution to generate the angles and the edges, respectively (Karimzade et al, 2017):…”

Section: Statistical Fracture Modelingmentioning

confidence: 99%

Three‐Dimensional Hydrochemical Model for Dissolutional Growth of Fractures in Karst Aquifers

Kang

Feng

et al. 2020

Water Resources Research

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This paper is intended to present a newly developed, comprehensive model to understand hydrochemical behaviors related to dissolutional growth of complex fractures underground. Under a fully implicit solution framework, the finite volume approach is employed to solve the reactive‐convective‐dispersive system. Based on the embedded discrete fracture model, a novel modeling approach is proposed to describe dissolutional fractures with various apertures in three dimensions (3‐D). This model is verified against preexisting numerical models. Then, a 3‐D field case study regarding hypogene speleogenesis in a deep‐seated, artesian setting is carried out, based on field data concerning karst terrain compiled from Western Ukraine. Finally, we perform a case study to elucidate the finger‐like dissolution process related to a synthetic 3‐D fracture network in gypsum and limestone with heterogeneous aperture fields. Simulation results suggest that (a) the combination of the kinetic trigger mechanism and the transverse speleogenesis concept favors the generation of hierarchical caves in homogeneous fractures; (b) the mechanism of reactive infiltration instabilities determines dissolutional propagation in gypsum with rough fractures; and (c) in limestone, nonlinear kinetics matters for both uniform‐ and variable‐aperture fractures.

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Prediction of water inflow into underground excavations in fractured rocks using a 3D discrete fracture network (DFN) model

Cited by 22 publications

References 38 publications

A New Hydro-Mechanical Coupling Numerical Model for Predicting Water Inflow in Karst Tunnels Considering Deformable Fracture

A New Hydro-Mechanical Coupling Numerical Model for Predicting Water Inflow in Karst Tunnels Considering Deformable Fracture

Fracture distribution in overburden strata induced by underground mining

Three‐Dimensional Hydrochemical Model for Dissolutional Growth of Fractures in Karst Aquifers

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