Non-Darcy flow seepage characteristics of saturated broken rocks under compression with lateral constraint

Yu, Bangyong; Chen, Zhanqing; Ding, Qi-Le; Wang, Luzhen

doi:10.1016/j.ijmst.2016.09.025

Cited by 26 publications

(10 citation statements)

References 6 publications

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“…According to a large number of tests and literatures (Chen et al 2014a, b;Li et al 2011;Yang et al 2007;Yu et al 2016), the relation among permeability parameters k, non-Darcy flow β factor, and acceleration coefficient c a satisfies the exponential relationship…”

Section: Calculation Of Permeability Parametersmentioning

confidence: 99%

Experimental investigation on the seepage property of saturated broken red sandstone of continuous gradation

et al. 2017

Bull Eng Geol Environ

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The statues of seepage in broken red sandstone may become unsteady due to the effects of water erosion, so it is important to consider the effect of mass loss on the permeability of broken red sandstone. In this study, the seepage property and water outburst were measured through a self-made variable mass seepage experimental system. In the test, the particles of broken red sandstone satisfied the Talbol grading theory. The influences of Talbol index n on the hydraulic, mass loss of particles, porosity and permeability were investigated. The experimental results show that the seepage process in the broken red sandstone usually experiences three stages: the initial stage, mutation stage and stabilization stage. Broken specimens can bear water erosion at the initial stage. However, the internal structure of specimens produces instability because the seepage of small particles gradually increases in the mutation stage. Finally, stable underground watercourses of the specimen were formed at the stabilization stage. It is also found that the mass loss, the peak of mass loss rate, the final porosity after seepage, the permeability at the mutation and stable stages were negatively related to the Talbol index n of the specimen. The seepage mutation occurred sooner for smaller n. The permeabilities of specimens with different Talbol indices differed by more than 10 times after seepage mutation.

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Section: Calculation Of Permeability Parametersmentioning

confidence: 99%

Experimental investigation on the seepage property of saturated broken red sandstone of continuous gradation

et al. 2017

Bull Eng Geol Environ

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“…en, the steady-state seepage method is used to carry out the test and record the data [22][23][24]. Previous research on the characteristics of cemented fractured rock showed that when the seepage time reached 3000 s, the decrease in the permeability was about 73%-96% of the total reduction at 6000 s, with the permeability decrease slowing in the later stages of penetration [19]. erefore, in this test, to eliminate the test error caused by the creep effect of coal rock, the stress holding time at each stage was set at 3000 s.…”

Section: Test Methodsmentioning

confidence: 99%

“…According to the rock test requirements [16,17], D of the sample to the maximum particle diameter d should satisfy D/d ≥ 5; therefore, the maximum particle size in the test was 10 mm. en, considering the long-term effect of KCP evolution, Wang et al [18] carried out the experiment by preparing a weak cementation structure; according to the cement content requirements for the fracture testing of the fractured mudstone, the cementing material was selected as standard 425 cement, and the optimum amount of cement per specimen was selected as 50 g. e selection of the particle size is based on the Talbot index theory [18] and the continuous grading theory [19], which defines the Talbot index n to range from 0-1, so this test takesn � 0.1, 0.2, . .…”

Section: Sample Preparationmentioning

confidence: 99%

Determining the Seepage Stability of Fractured Coal Rock in the Karst Collapse Pillar

Zhang

Pang

Zhang

et al. 2020

Advances in Civil Engineering

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The karst collapse pillar (KCP) is a common geological structure in the coal mines of northern China. KCPs contain many fractured coal rocks, which can easily migrate under the action of high-pressure water. The destruction or instability of the cementation structure between the rocks can directly induce coalmine water-inrush accidents. To study the seepage stability of cemented and fractured coal rock under triaxial pressures, a self-designed triaxial seepage testing system was used and the permeability k and non-Darcy factor β of the cemented and fractured coal rock were tested. Furthermore, the 1D non-Darcy seepage equations were used to calculate the evolution criteria of the seepage loss stability. The results show the following: (1) The cemented structure in the KCP under the triaxial pressures can be easily destroyed. The damaged coal and rock body mainly exists in bulk form, and the permeability depends mainly on the effective stress of the particles. (2) The seepage process in the KCP structure is a combination of pore flow, fracture flow, and pipe flow, and the transition of the seepage state is closely related to the change in the magnitude of β. (3) Under the long-term effect of confined underground water, the migration of small fractured particles in the KCP will increase the structural porosity. If the parameter βk2 reaches the threshold value, the seepage system will evolve into a pipeline flow state, eventually causing a water-inrush accident.

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“…A low porosity is a sufficient but not necessary condition for low permeability; similarly, a high permeability is also a sufficient but not necessary condition for high porosity. For some high-porosity coal samples, the permeability may be low and the non-Darcy coefficient increases gradually with the increase of permeability [54,55].…”

Section: An Analysis Of the Relationship Between The Seepagementioning

confidence: 99%

Simulation Analysis on Water’s Micro Seepage Laws under Different Pressure Gradients Using Computed Tomography Method

Zhou

Qiu

Zhang

et al. 2018

Advances in Civil Engineering

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The aim of this paper was to develop a model that can characterize the actual micropore structures in coal and gain an in-depth insight into water’s seepage rules in coal pores under different pressure gradients from a microscopic perspective. To achieve this goal, long-flame coals were first scanned by an X-ray 3D microscope; then, through a representative elementary volume (REV) analysis, the optimal side length was determined to be 60 μm; subsequently, by using Avizo software, the coal’s micropore structures were acquired. Considering that the porosity varies in the same coal sample, this study selected four regions in the sample for an in-depth analysis. Moreover, numerical simulations on water’s seepage behaviors in coal under 30 different pressure gradients were performed. The results show that (1) the variation of the simulated seepage velocity and pressure gradient accorded with Forchheimer’s high-velocity nonlinear seepage rules; (2) the permeability did not necessarily increase with the increase of the effective porosity; (3) in the same model, under different pressure gradients, the average seepage pressure decreased gradually, while the average seepage velocity and average mass flow varied greatly with the increase of the seepage length; and (4) under the same pressure gradient, the increase of the average mass flow from the inlet to the outlet became more significant under a higher inlet pressure.

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Non-Darcy flow seepage characteristics of saturated broken rocks under compression with lateral constraint

Cited by 26 publications

References 6 publications

Experimental investigation on the seepage property of saturated broken red sandstone of continuous gradation

Experimental investigation on the seepage property of saturated broken red sandstone of continuous gradation

Determining the Seepage Stability of Fractured Coal Rock in the Karst Collapse Pillar

Simulation Analysis on Water’s Micro Seepage Laws under Different Pressure Gradients Using Computed Tomography Method

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