Dynamic Crack Initiation Toughness of Shale under Impact Loading

Yang, Guoliang; Li, Xuguang; Bi, Jingjiu; Shuaijie, Cheng

doi:10.3390/en12091636

Cited by 3 publications

(2 citation statements)

References 9 publications

(14 reference statements)

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“…The results show that the greater the angle of the prefabricated fissure, the greater the maximum pore pressure at which the specimen ruptures. The damage pattern also shows various anisotropies with the fracture's angle (Yang et al, 2019). used Hopkinson compression bars for impact loading of semicircular bent shale specimens containing cracked notches, the results show that the laminar surface changes the direction of crack extension.…”

Section: Introductionmentioning

confidence: 89%

Three-dimensional numerical simulation study of pre-cracked shale based on CT technology

Wu²,

Zuo³

et al. 2023

Front. Earth Sci.

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Due to the heterogeneity of rock media, it is difficult to truly reflect its internal three-dimensional microstructure in physical tests or numerical simulation. In this study, CT scanning technology and numerical image processing technology are used, and the finite element software RFPA-3D is used to establish a three-dimensional non-uniform numerical model that can reflect the meso structure of rock mass. In order to study the fracture mechanism of shale with prefabricated fractures, seven groups of three-dimensional numerical models with prefabricated fractures from different angles were constructed, and Brazilian fracturing numerical simulation tests were carried out. The results show that method of reconstructing 3D numerical models by CT scanning is feasible and provides a viable method for in-depth study of the micromechanics of shale. Prefabricated fractures and quartz minerals have significant effects on the tensile strength of shale, and both will weaken the destructive strength of shale specimens. The damage modes of Brazilian disc specimens containing prefabricated fissures can be divided into four categories. The damage process is divided into budding, plateauing and surge periods by acoustic emission. The crack initiation angle of the prefabricated fissure tip increases with increasing fissure angle, and the MTS criterion can be used as a basis for judging prefabricated fissure initiation. The results of the study are important guidance for the fracture initiation mechanism and fracture expansion law of the fractured layer containing natural fractures in the hydraulic fracturing process.

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Section: Introductionmentioning

confidence: 89%

Three-dimensional numerical simulation study of pre-cracked shale based on CT technology

Wu²,

Zuo³

et al. 2023

Front. Earth Sci.

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“…In recent years, many experimental and theoretical studies have been conducted on the mechanical anisotropic behavior of bedded shale (Chao et al 2023;Dong et al 2019;Yang et al 2019;Raef et al 2018). Experimental investigations have mainly focused on conventional dynamic uniaxial compression and direct shear tests (Heng et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Study of the Dynamic Failure Characteristics of Anisotropic Shales Under Impact Brazilian Splitting

Feng,

Gong,

Liang

et al. 2023

Rock Mech Rock Eng

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The mechanical behaviors of shales with transversely isotropic characteristics under dynamic loading have great significance for structural instability in geotechnical engineering. To understand the effect of transverse isotropy on the deformability and tensile strength of shales subjected to dynamic loading, a group of impact Brazilian tests were carried out on shale specimens via a split Hopkinson pressure bar (SHPB) testing system. High-speed digital image correlation technology was applied to monitor the fracture process. The experimental results demonstrate that the failure strength has considerable anisotropy as the bedding angle of the embedded layers changes. Moreover, the tensile strength of shales with vertical bedding is usually higher than that of shales with parallel bedding. The observed failure mode is mainly the interaction between tensile and/or shear fractures, and with increasing loading rate, layer-activated fractures tend to occur. Furthermore, five typical failure patterns of transversely isotropic shales characterized by different mechanisms under dynamic Brazilian testing were found. The shales were sensitive to the strain rate when the deformation and fracture response under dynamic loading were assessed. In addition, the modified Nova‒Zaninetti criterion that considers the strain rate effect was proposed according to the Brazilian splitting data and dynamic coordinate system. The established criterion not only properly represents the law of dynamic strength but also provides a new understanding of the effect of strain rate on strength. It has proven to be effective for predicting the dynamic strength characteristics of shales.

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