Mechanical and hydraulic behavior of a rock fracture under shear deformation

Nishiyama, Satoshi; Ohnishi, Yuzo; Ito, Hisao; Yano, Takao

doi:10.1186/1880-5981-66-108

Cited by 19 publications

(7 citation statements)

References 50 publications

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“…The different stress conditions may lead to the fracture opening/closure or shear dilation, which is sensitive to the seepage characteristics. Laboratory experiments under triaxial compression or direct shear have been carried out to study the relationship between the confinement or normal stress and permeability on rock mass or a single rock fracture [ 10 , 12 , 32 , 33 , 34 ]. Besides, various models of permeability tensors were built to describe the permeability of fracture network in the rock mass and have been used in field engineering under different stress conditions [ 35 , 36 , 37 ].…”

Section: Introductionmentioning

confidence: 99%

Failure Behavior of Granite Affected by Confinement and Water Pressure and Its Influence on the Seepage Behavior by Laboratory Experiments

Cheng

et al. 2017

Materials

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Failure behavior of granite material is paramount for host rock stability of geological repositories for high-level waste (HLW) disposal. Failure behavior also affects the seepage behavior related to transportation of radionuclide. Few of the published studies gave a consistent analysis on how confinement and water pressure affect the failure behavior, which in turn influences the seepage behavior of the rock during the damage process. Based on a series of laboratory experiments on NRG01 granite samples cored from Alxa area, a candidate area for China’s HLW disposal, this paper presents some detailed observations and analyses for a better understanding on the failure mechanism and seepage behavior of the samples under different confinements and water pressure. The main findings of this study are as follows: (1) Strength reduction properties were found for the granite under water pressure. Besides, the complete axial stress–strain curves show more obvious yielding process in the pre-peak region and a more gradual stress drop in the post-peak region; (2) Shear fracturing pattern is more likely to form in the granite samples with the effect of water pressure, even under much lower confinements, than the predictions from the conventional triaxial compressive results; (3) Four stages of inflow rate curves are divided and the seepage behaviors are found to depend on the failure behavior affected by the confinement and water pressure.

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Section: Introductionmentioning

confidence: 99%

Failure Behavior of Granite Affected by Confinement and Water Pressure and Its Influence on the Seepage Behavior by Laboratory Experiments

Cheng

et al. 2017

Materials

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“…The critical fluid pressure leading to the channeling mechanism in the damage zone along the fault is a key parameter that will determine the behavior of clay fault conduit, even if the fault is considered as inactive [Jeanne et al, 2018]. This has also been observed at the laboratory scale for fluid injection in a fault zone for different type of rocks, where the fluid was channeling at pressure much lower than the minimum value to trigger a mechanical instability [Nishiyama et al, 2014;Cuss et al, 2016].…”

Section: Discussionmentioning

confidence: 85%

Fluid migration in faulted shale rocks: channeling below active faulting threshold

Donzé

Tsopela

Guglielmi

et al. 2020

European Journal of Environmental and Civil Engineering

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During fluid injection tests performed inside the clay-rich Tournemire fault zone, the monitored fault displacement exhibited limited amplitudes whereas a sharp increase of the permeability occurred as the fluid pressure reached a threshold value. The injected fluid channeled through the fractured zone or at the interface between the host rock and the fault core over decameter distances without triggering large irreversible deformation of the fault zone. To assess the underlying hydro-mechanical mechanisms of this sudden increase of permeability, a numerical model was set up to simulate an injection test inside a fracture. When the fluid pressure outweighs the mechanical contribution of the heterogeneities along the fracture planes, the sudden increase of permeability appears. The existence of the channeling process, occurring below a critical fluid pressure at the fracture scale, could explain why it is possible to generate fault leakage inside a non-active fault zone crossing shale rocks. Based on the in-situ and laboratory monitoring, an analytical expression based on TPHM (Two-Part Hooke's Model) can reproduce the stress-dependent permeability evolution. For low values of the effective stress, a simple cubic law formulation does not reproduce correctly the sharp increase of permeability identified once the Fracture Opening Pressure (FOP) is reached.

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“…Both measures contribute to improving the similitude between the printing material and natural rocks to a certain extent. However, natural rocks inevitably contain many initial random imperfections, such as micro/meso-scale pores, fractures and joints 48 – 50 . These physical characteristics considerably vary the mechanical behaviour of rocks.…”

Section: Discussionmentioning

confidence: 99%

The mechanical and photoelastic properties of 3D printable stress-visualized materials

Xie

et al. 2017

Sci Rep

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Three-dimensional (3D) printing technology integrating frozen stress techniques has created a novel way to directly represent and characterize 3D interior discontinuities and the full-field stress induced by mining- or construction-related disturbances of deeply buried rock masses. However, concerns have been raised about the similitude between the mechanical behaviours of the printed model and its prototype rock mass. Ensuring the mechanical properties of the printable materials are as close as possible to those of real rock mass is of critical significance. In this work, a transparent, light, photosensitive polymer material was investigated for applications in frozen stress tests. The chemical composition of the material was determined by integrating the results of infrared spectroscopy (IR spectroscopy), X-ray diffraction (XRD), pyrolysis, gas chromatography and mass spectrometry (PY-GC/MS). Measures to improve the mechanical properties of the printable material, including printing orientation, post-processing, and temperature control, were evaluated by comparing the treated material with its prototype rock. The optical stress sensitivity of the material, including stress-visualized properties and stress-frozen performance, was also tested. This study offers an understanding of how printable materials should be modified to better simulate real rock masses, in terms of not only their geological geometry but also their mechanical performance.

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Mechanical and hydraulic behavior of a rock fracture under shear deformation

Cited by 19 publications

References 50 publications

Failure Behavior of Granite Affected by Confinement and Water Pressure and Its Influence on the Seepage Behavior by Laboratory Experiments

Failure Behavior of Granite Affected by Confinement and Water Pressure and Its Influence on the Seepage Behavior by Laboratory Experiments

Fluid migration in faulted shale rocks: channeling below active faulting threshold

The mechanical and photoelastic properties of 3D printable stress-visualized materials

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