Experimental and Numerical Study on Hydromechanical Coupled Deformation Behavior of Beishan Granite considering Permeability Evolution

Wang, Zi-hui; Ren, W.G.; Tan, Yunliang; Konietzky, Heinz

doi:10.1155/2020/8855439

Cited by 10 publications

(7 citation statements)

References 40 publications

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“…By monitoring the cracks in the failure process, the total number of cracks showed the trend of first increasing and then decreasing with the increase of the internal mica content. Moreover, it existed a clear peak when the mica content was 20%; on the crystal interface, the ratio of cracks to the total cracks decreased with the increase 13 Geofluids of L, and the result was more obviously affected by the mica component (4) The test results show a significant correlation between fracture development and fabric distribution of different fabric rocks under external load, and corresponding technologies should be adopted for different fabric rocks in hydraulic fracturing…”

Section: Discussionmentioning

confidence: 88%

“…In fact, in the construction process, the physical and mechanical properties of the rock itself have a great impact on the construction of hydraulic fracturing. Xia et al [1][2][3][4] studied the crack propagation path of samples of heterogeneous rock with different microfractures by CT scanning 3D imaging technology, and it was found that the fractures of hydraulic fracturing were easy to generate along with the natural fractures and joints to interact with each other, forming complex network fractures. Therefore, the study of the relationship between the distribution of rock fab-ric and the fracture distribution can further promote understanding the hydraulic fracturing mechanism.…”

Section: Introductionmentioning

confidence: 99%

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Study on the Tensile Strength and Crack Development of Granite Crystal Models with Different Fabrics

Chen

2021

Geofluids

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According to the relationship between the development of hydraulic fracture and the distribution of different rock and mineral fabrics, digital image technology was used in this study based on the discrete element particle flow method. An SCGM numerical model, which can control fabric and refine mesoscopic crystal defects, was constructed. The tensile strength test of granite specimens with different component contents and polymerization conditions was conducted, with the monitorization of damaged cracks. The test results showed that (1) the SCGM model could construct a model of a crystal structure containing variable components and polymerization, to achieve numerical experiments of different parameters; (2) compared with previous models, the SCGM model can reflect internal stress change of a specimen with the variation of the structure. At the same time, the contained crystal structure can characterize different failure modes such as intergranular cracks of different components, grain boundary cracks of the same component, and transgranular cracks, which were in good agreement with the actual failure state of granite; (3) the mica content of the specimen and its strength presented a linear relationship of y = − 14.723 x + 12.642 . The degree of polymerization of the components and the strength of the specimens were both affected by the accumulation of microcracks and stress concentration, which appeared to increase first and then decrease. When the specimen was broken, the number of microcracks and the degree of polymerization of the components also increased first and then decreased. The SCGM model can construct a numerical model of granite with arbitrary fabric and crystal structure and provide a hydraulic fracturing analysis method.

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Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Study on the Tensile Strength and Crack Development of Granite Crystal Models with Different Fabrics

Chen

2021

Geofluids

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“…And pore pressures were set to 2, 4, 6, and 8 MPa, which mirrors the maximum potential water pressure at different buried depth in Beishan region [44]. The desired confining pressure and fluid pressure were reached with a constant loading rate of 0.05 MPa/s and 1 MPa/min, respectively [45]. Afterwards, the axial load was increased with a constant rate of 30 kN/min.…”

Section: Mechanical Test Facility and Testingmentioning

confidence: 99%

Experimental Study on Physical and Mechanical Properties of Beishan Granite after Cyclic Heating and Cooling with Water

Wang

Guo

Li³

et al. 2022

Lithosphere

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Granite characterized by low permeability and high strength is commonly seen in underground construction. This paper is aiming at studying the influence of cyclic heating and water cooling on physicomechanical properties of Beishan granite, which is chosen as a potential host surrounding rock of a high level nuclear waste (HLW) repository. In this study, physical and mechanical properties of Beishan granite after repeated heating-cooling cycles are described. After five heating-cooling cycles with temperature up to 300°C, the diameter and length of specimens increase by 0.090% and 0.052%, respectively. And the mass of specimen reduces by 0.32 g. In the following conventional triaxial compression (CTC) tests, the peak strength shows a slightly increase, but the dilatancy threshold decreases. And both peak strain and dilatancy threshold strain exhibit increase, which is responsible for the decrease of Young’s modulus. During the test, acoustic emission (AE) is rarely monitored in the early loading and starts to generate systematically when the axial stress is beyond dilatancy threshold. On the other hand, in the hydraulic (HM) coupled experiments, both peak strength and dilatancy threshold show decrease. However, the ratio between dilatancy threshold and peak strength shows slightly increase. The same phenomenon can be observed for the peak strength and dilatancy threshold. The permeability shows rarely change compared with that of the specimen without experienced cyclic heating-cooling. AE is significantly monitored in the initial loading, which is seem more than that generated from dilatancy threshold to peak strength. The obtained results are useful for the construction of HLW repository.

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“…e constant compressive displacement rate is set to 5e-8 m/step, which will be applied on end faces of the model in the following simulation. Based on the tests in Section 3 and reference [14], the input parameters are determined, as shown in Table 4. e validation of this numerical method has been proven by Tan [37].…”

Section: Model Description and Setupmentioning

confidence: 99%

“…As a natural material, rocks contain microcracks. It has been widely recognized that the growth of microcracks associated with crack propagation and coalescence can ultimately cause crystalline rock failure [4][5][6][7][8][9][10][11][12][13][14][15][16]. Wawersik and Brace conducted compression experiments on Westerly granite, indicating that at low confining pressure faulting in granite occurs only in the post-failure region beyond the peak of the stress-strain curves [5].…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study on Mechanical Properties and Deformation Behavior of Beishan Granite considering Heterogeneity

Wang

Tan

Li³

et al. 2021

Advances in Civil Engineering

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Disposal of high-level radioactive waste (HLW) deep underground is one of the most challenging research subjects in rock engineering. In China, Beishan granite is usually chosen as host rock for the construction of the HLW repository. In this study, mechanical tests are conducted on Beishan granite and the stress-strain state during the complete failure process is analyzed by numerical simulation. The results show that the tensile strength and uniaxial compressive strength of Beishan granite are 8.66 and 162.9 MPa, respectively. Dilatancy appears when the stress reaches about 81% of the peak strength. Heterogeneity is introduced by Weibull distribution in numerical simulation. With the increase of homogenization degree, the degraded elements are more easily to concentrate locally. Based on experimental and numerical simulation results, it is noticeable that the sample volume is basically in the state of compaction before reaching the peak strength. The elements are more likely to show expansion, and the splitting failure dominates the destroy mode when the confining pressure is relatively low. With increasing confining pressure, more and more degraded elements are concentrated in the shear band, which develops from the surface to the interior of the sample during loading. Therefore, the granite shows ductile mechanical response characteristics when the confining pressure is relatively high. The results are instructive for the construction of the repository.

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Experimental and Numerical Study on Hydromechanical Coupled Deformation Behavior of Beishan Granite considering Permeability Evolution

Cited by 10 publications

References 40 publications

Study on the Tensile Strength and Crack Development of Granite Crystal Models with Different Fabrics

Study on the Tensile Strength and Crack Development of Granite Crystal Models with Different Fabrics

Experimental Study on Physical and Mechanical Properties of Beishan Granite after Cyclic Heating and Cooling with Water

Experimental and Numerical Study on Mechanical Properties and Deformation Behavior of Beishan Granite considering Heterogeneity

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