Influences of connectivity and conductivity on nonlinear flow behaviours through three-dimension discrete fracture networks

Feng, Xu; Jiang, Qinghui; Xu, Chaoshui; Zhang, Xiaobo; Zhang, Qihua

doi:10.1016/j.compgeo.2018.11.014

Cited by 71 publications

(25 citation statements)

References 49 publications

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“…Permeability characterizes the ability of porous materials to transport liquids. According to previous studies, permeability is positively correlated with material porosity and pore size, In addition, the permeability is also related to the number of pores, the degree of tortuosity of the fluid flow path [52], and the connectivity of the pore network [53]. This paper chooses the Coates model [54], [55], which is currently more commonly applied to water-only pore structures.…”

Section: Permeability Evolutionmentioning

confidence: 99%

Study on Microstructural Evolution of Marble Under Cyclic Dynamic Impact Based on NMR

et al. 2019

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In this paper, the evolution process of microstructures of fine-grained marble and coarse-grained marble under cyclic dynamic impact is studied. The split Hopkins pressure bars (SHPB) are used to apply multiple impacts on rock samples with a constant dynamic stress. And the microstructural changes caused by each impact were detected by a nuclear magnetic resonance (NMR) system. Porosity, transverse relaxation time (T 2) spectral distribution, pore size distribution and magnetic resonance imaging under different dynamic impact cycles were obtained, and the evolution of the T 2 cutoff value (T 2c) of the rock was obtained by combining the centrifugal technique to calculate the permeability. The pores were classified into two categories according to the pore size and the fluidity of the fluid in the pores to study the effect of impact on the pore connectivity. According to the results of X-ray fluorescence (XRF) and X-ray diffractometry (XRD), it is found that the two marbles are the same in mineral composition but different in composition ratios. Due to the difference in particle size of marble and the difference in the number of pores, the magnitudes of microstructure changes of the two marbles are different, but they have a consistent trend: under the cyclic dynamic impact, the porosity of the two marbles gradually decreases, the pore size continues to decrease, the marble framework is compacted, the pore structure is gradually closed, and the permeability is weakened. The weakening of rock permeability is mainly caused by the overall decrease in pore size and loss of pore connectivity. INDEX TERMS Cyclic dynamic impacts, nuclear magnetic resonance, pore size, pore connectivity, permeability.

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Section: Permeability Evolutionmentioning

confidence: 99%

Study on Microstructural Evolution of Marble Under Cyclic Dynamic Impact Based on NMR

et al. 2019

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“…The construction of metro tunnels in underground space of urban with complex geological structures will inevitably produce the adverse effects on existing structures around the tunnels. The geology condition is also an issue to be considered, like groundwater, soft soil layer, fractures and so on [1], [2], [3], [4], [5]. How to predict the problems in advance and take effective measures to reduce these impacts have become a key factor to be solved for the tunnel excavation projects.…”

Section: Introductionmentioning

confidence: 99%

Influence of Metro Tunnel Excavation on Deformation of Existing Pedestrian Underpass in Changzhou Railway Station Platform

Yang¹,

Wang²

2020

IEEE Access

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In order to predict the impact of Changzhou Metro Line 1 passing through the pedestrian underpass of Changzhou Station in Shanghai-Nanjing Intercity Railway, FLAC3D software is used to simulate the excavation of the left and right subway tunnel lines step by step. The influences of existing and non-exiting pedestrian underpass on subsurface settlement are compared, and the deformation and stress distribution of the pedestrian underpass are analyzed. Additionally, the numerical results are verified by filed monitoring. The calculation and monitoring results show that the existence of the pedestrian underpass causes a relatively obvious ''barrier'' effect, which makes the vertical displacement changes with increasing of depth, and consequently causes the uneven vertical displacement. The tunnel excavation mainly causes the inclination of the pedestrian underpass, the floor deformation of the escalator channel, and the deformation difference occurs at the interface between escalator channel and pedestrian underpass; the existence of tunnel has little influence on the stress change of the pedestrian underpass. However, in order to protect from the concentration of stress, it is necessary to focus on monitoring the place where has a large stress during construction, such as, the right interface between pedestrian underpass and escalator channel, and the right exit of escalator channel.

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“…For a long time, the flow behavior of fluid is an intriguing research topic for seepage theory of fractured rock mass [11][12][13]. On the one hand, the structural form of fractures and the connectivity of the fracture network effectively control the fluid flow [14][15][16][17]. Chen et al [14] proposed a quantitative model to represent the relationship between the fracture geometric characteristics and the non-Darcy coefficient.…”

Section: Introductionmentioning

confidence: 99%

“…Chen et al [14] proposed a quantitative model to represent the relationship between the fracture geometric characteristics and the non-Darcy coefficient. The smoother the fracture surfaces and the greater the connectivity of the fracture network, the lower the hydraulic gradient for the onset of nonlinear flows [15]. Larger apertures, rougher fracture surfaces, and a greater number of intersections in a discrete fracture network would result in the onset of nonlinear flow at a lower critical hydraulic gradient [16].…”

Section: Introductionmentioning

confidence: 99%

Investigation on the Water Flow Evolution in a Filled Fracture under Seepage-Induced Erosion

Shao

Zhang

et al. 2020

Water

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Water inrush is a major geological hazard for safe mining and tunnel construction. For the water inrush channel containing mud, sand, and other sediments, it is difficult to predict the change of permeability and water surge, which makes disaster prevention difficult. As a typical water inrush channel, a filled fracture under seepage-induced erosion needs to be focused. In this work, a numerical model for the evolution of flow in a filled fracture under seepage-induced erosion was established, which included the seepage velocity, hydraulic erosion, and permeability of the filling medium. The effects of joint roughness coefficient (JRC) and homogeneity of the filling medium on the seepage evolution are discussed. The results showed that the fracture seepage properties experienced a non-linear change process, and the evolution can be divided into three phases: the slowly varying phase, the rapidly varying phase, and the stable phase. The increase of the JRC hindered the development in flow velocity and erosion. Compared with low homogeneous filling medium, pores in the high homogeneous filling medium were easier to expand and connect, and the seepage characteristics evolved faster. The model established in this study will help to understand the seepage evolution of filled fractures, and can be used to predict the permeability of filled fractures in engineering geology.

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Influences of connectivity and conductivity on nonlinear flow behaviours through three-dimension discrete fracture networks

Cited by 71 publications

References 49 publications

Study on Microstructural Evolution of Marble Under Cyclic Dynamic Impact Based on NMR

Study on Microstructural Evolution of Marble Under Cyclic Dynamic Impact Based on NMR

Influence of Metro Tunnel Excavation on Deformation of Existing Pedestrian Underpass in Changzhou Railway Station Platform

Investigation on the Water Flow Evolution in a Filled Fracture under Seepage-Induced Erosion

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