Solid grain migration on hydraulic properties of fault rocks in underground mining tunnel: Radial seepage experiments and verification of permeability prediction

Ma, Dexin; Duan, Hongyu; Zhang, Jixiong

doi:10.1016/j.tust.2022.104525

Cited by 92 publications

(34 citation statements)

References 50 publications

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“…The wide distribution of karst landscapes poses a serious threat for the safety construction of transportation engineering in China [1,2]. Underground engineering in karst areas encounters more complex geological conditions, with highly developed karst fissures.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Response of Surrounding Rock of Karst Tunnel under Stress-Damage-Seepage Coupling Effect

Cao

Duan³

et al. 2022

Geofluids

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In order to reveal the mechanical response of surrounding rock of karst tunnel under stress-damage-seepage coupling effect, a new damage constitutive mechanical model of surrounding rock of karst tunnel under stress-damage-seepage coupling effect is established, which is calculated by the COMSOL Multiphysics in this paper. When the mechanical parameters are assigned to microelements of rock mass by the Weibull distribution function, the larger the m value is, the more homogeneous the rock mass is. The variation trend of strain energy density with m is similar to equivalent stress, which increases firstly and then decreases. The number of damage points increases with the increase in loading step and decreases rapidly after reaching the peak value and then remains a small number in the later loading stage. With the increase in γ , the stress range expands to the rock mass above the vault and below the floor; the stress value increases significantly, and the surrounding rock of karst tunnel is closer to strength limit, leading to the damage of rock mass. With the increase in γ , the area of the damage area in the upper part of the vault becomes larger, and most of the rock mass below the bottom plate is damaged; the damage area is semicircular, which indicates that both places are damaged by shearing action, resulting in the developed fissures. Besides, there are the distribution characteristics of “high value on both sides with a peak value and low value in the middle position” in the permeability distribution, and high permeability is located at the arch foot, and the low permeability is located at the floor. The larger the value of γ , the larger the permeability. The research achievements provide an important theoretical basis for prediction and treatment for dynamical disaster of karst tunnel.

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Section: Introductionmentioning

confidence: 99%

Mechanical Response of Surrounding Rock of Karst Tunnel under Stress-Damage-Seepage Coupling Effect

Cao

Duan³

et al. 2022

Geofluids

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“…At the same time, the loose medium and mineral components of the fault are dissolved in the water body, and the seepage channel expands. In turn, the seepage rate of the rock mass will be increased, forming a "vicious circle," resulting in the original rock structure damage [1,2]. Especially for deep-buried tunnels, the surrounding rock is subject to higher ground stress and water pressure, and the hydraulic coupling effect is intensified, which can easily lead to engineering disasters such as water and mud inrush [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Research on the Safety Thickness of Tunnel Outburst Prevention in Water-Rich Fault Fracture Zone Based on Janssen’s Theory

Zhong

Zhou

2022

Geofluids

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In the construction of tunnel in water-rich fault fracture zone, when the thickness of outburst prevention is insufficient, it is very easy to cause water and mud inrush engineering accident. Therefore, it is very necessary to study the safety thickness of outburst prevention for this type of tunnel. In this paper, the expression of in situ stress in water-rich fault fracture zone is derived based on Janssen’s theory. Two mechanical models of outburst prevention rock mass are established, and according to the shear balance theory, the calculation formula for the safe thickness of outburst prevention is determined and the parameter sensitivity analysis is carried out. Finally, it is verified by engineering examples and numerical simulation. The results show that: (1) the calculation formula of outburst prevention thickness proposed in this paper is more perfect and shows good prediction effect for deep- and shallow-buried tunnels; (2) the greater the angle α between tunnel axis and fault zone and the dip θ of fault fracture zone, the smaller the critical safety thickness of outburst prevention and the safer it is for tunnel construction; (3) when the fault fracture zone inclines inward relative to the tunnel face, the gravity of the rock mass in the fault zone will lead to an increase in the safety thickness of outburst prevention, and reinforcement measures should be taken during actual construction.

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“…Some theoretical and field experimental studies on fracturing or penetration fracturing through a coal seam roof have been carried out. To date, the related research focuses on the effects of fracturing parameters and perforation parameters on crossing layer fracture propagation [12][13][14][15], optimization of development technology of horizontal wells in a coal seam roof [16,17], fracture initiation pressure of a coal seam or coal seam roof [18,19], properties of different roof rocks of a coal seam [20], fracture characteristics of rock mass during mining [21][22][23], and the effects of coal mechanical parameters on proppant embedding [24,25]. However, few studies on favorable geological conditions suitable for fracturing through horizontal wells in a coal seam roof have been reported.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation Investigation on Fracture Propagation of Fracturing for Crossing Coal Seam Roof

Xiao

Wang

2022

Processes

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The fracturing crossing coal seam roof is a technology that fulfills the fracturing of a coal seam through the vertical propagation of fractures. Geological conditions are the key factors determining the effect of this kind of fracturing, but there is hardly any research on this aspect. To determine the favorable geological conditions for through-roof fracturing, based on a 3D fracture propagation model, and considering the interlayer vertical fracture toughness and leak-off heterogeneity, a mathematical model of fracturing through a horizontal well in a coal seam roof was established, and the calculation method of fractures crossing layer propagation was determined. In this method, the effect of fracture communication with the coal seam is evaluated by taking the area and the area ratio of fractures in the coal seam as the objective functions. The effects of parameters such as in situ stress combination profile, coal seam fracture toughness, and fluid loss coefficient on fracturing results were evaluated. The reasonable distance from the horizontal well to the coal seam’s top surface was determined in this work. The study results show that: (i) the fracturing effect is better when the coal seam is lower in in situ stress; (ii) the distance between the horizontal well and the top surface of the coal seam is recommended to be less than 4 m to obtain the ideal fracturing effect; and (iii) the combination of the in situ stress profile is the key factor, and the fracture toughness and fluid loss coefficient of the coal seam, fluid viscosity, and the number of perforations in one cluster are the secondary factors affecting the fracturing effect.

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Solid grain migration on hydraulic properties of fault rocks in underground mining tunnel: Radial seepage experiments and verification of permeability prediction

Cited by 92 publications

References 50 publications

Mechanical Response of Surrounding Rock of Karst Tunnel under Stress-Damage-Seepage Coupling Effect

Mechanical Response of Surrounding Rock of Karst Tunnel under Stress-Damage-Seepage Coupling Effect

Research on the Safety Thickness of Tunnel Outburst Prevention in Water-Rich Fault Fracture Zone Based on Janssen’s Theory

Numerical Simulation Investigation on Fracture Propagation of Fracturing for Crossing Coal Seam Roof

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