Investigation of the fracture modes of red sandstone using XFEM and acoustic emissions

Wang, Hongjian; Liu, Da’an; Cui, Zhijiu; Cheng, Cheng; Zhou, Jian

doi:10.1016/j.tafmec.2016.03.012

Cited by 93 publications

(34 citation statements)

References 26 publications

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“…The deformation characteristics of microcracks at the tip of the preformed notch can be studied by numerical simulation. 30,31,23 To get the inherent effect of loading mode on crack growth mechanism of rock, the beam model of 400 mm 3 100 mm 3 50 mm is established by explicit finite element software ANSYS/LS-DYNA. A notch with a width of 1 mm and a height of 10 mm is set in the middle of the model, as shown in the Figure 12.…”

Section: Methods and Modelmentioning

confidence: 99%

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Experimental and numerical studies on fracture characteristics of notched granite beams under cyclic loading and unloading

Tang

et al. 2020

The Journal of Strain Analysis for Engineering Design

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In underground engineering, such as mining engineering and deep tunnel engineering, the rock is often loaded and unloaded repeatedly. The strength of rock under cyclic load is lower than that under static load. To obtain the fracture response of the rock, the three-point bending tests of notched granite beams under cyclic loading and unloading were carried out with Electro-hydraulic Servo Material Test System. The acoustic emission technology was adopted to monitor the acoustic emission events of sample in the process of fracture. It is revealed that the fracture toughness of granite under cyclic loading and unloading is lower than that under static loading. Based on the acoustic emission energy obtained from monitoring, the damage evolution during cyclic loading and unloading was analyzed. The fracture mode of granite samples is analyzed by the RA value-average frequency correlation method. And the Felicity ratio during the loading and unloading cycle was calculated to evaluate the severity of initial damage of the material. It is revealed that Kaiser effect appears only in the elastic deformation stage of cyclic loading unloading bending. The Holmquist–Johnson–Cook damage constitutive model and Weibull distribution were used to establish the heterogeneous granite model. And the three-point bending of the model under cyclic loading and unloading was simulated to disclose the crack growth mechanism of rock. The study may provide some references for rock instability control in geotechnical engineering construction.

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Section: Methods and Modelmentioning

confidence: 99%

“…The distribution of the RA values with increasing AF carries the most important fracture information. 23 AF and RA values can be used to distinguish different crack modes. Low RA value and high AF represent the development of opening cracks, otherwise they represent shear cracks.…”

Section: Ae Characteristics Of Granite Samples In Tpb Testsmentioning

confidence: 99%

Experimental and numerical studies on fracture characteristics of notched granite beams under cyclic loading and unloading

Tang

et al. 2020

The Journal of Strain Analysis for Engineering Design

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“…The actual physical and mechanical process of crack initiation and propagation can be directly observed using these tests by simulating the actual formation conditions. Additionally, the various factors that influence crack initiation and propagation can be separated and analyzed individually to determine which factors are the most significant [38,39].…”

Section: Test Apparatus and Sample Preparationmentioning

confidence: 99%

Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States

et al. 2021

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Shale gas can be commercially produced using the stimulated reservoir volume (SRV) with multistage fracturing or multiwell synchronous fracturing. These fracturing technologies can produce additional stress fields that significantly influence the crack initiation pressure and the formation of an effective fracture network. Therefore, this study primarily investigated the evolution of crack initiation and propagation in a hydraulic rock mass under various stress conditions. Combining the in situ stress characteristics of a shale reservoir and fracturing technology, three types of true triaxial volumetric fracturing simulation experiments were designed and performed on shale, including three-dimensional constant loading, one-dimensional pressurization disturbance, and one-dimensional depressurization disturbance. The results indicate that the critical failure strength of the shale rock increases as the three-dimensional constant loads are increased. The rupture surface is always parallel to the maximum principal stress plane in both the simulated vertical and horizontal wells. Under the same in situ stress conditions in the wellbore direction, if the lateral pressure becomes larger, the critical failure strength of shale rock would increase. Additionally, when the lateral in situ stress difference coefficient is smaller, the rock specimen has an evident trend to form more complex cracks. When the shale rock was subjected to lateral disturbance loads, the critical failure strength was approximately 10 MPa less than that in the state of constant loading, indicating that the specimen with disturbance loads is more likely to be fractured. Moreover, shale rock under the depressurization disturbance load is more easily fractured compared with the pressurization disturbance. These findings could provide a theoretical basis and technical support for multistage or multiwell synchronous fracturing in shale gas production.

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“…(16,(19)(20)(21) Many research results show that there is a very close relationship between AE phenomena and material fracture. (22)(23)(24)(25)(26)(27) Therefore, AE monitoring has the potential to achieve remote real-time monitoring of the initiation and propagation of SCC. AE phenomena refers to elastic wave phenomena in materials and structures produced by stress or fracture due to the rapid release of energy.…”

Section: Introductionmentioning

confidence: 99%

Characteristic of Acoustic Emission Signal from Stress Corrosion Cracking in Low-Carbon Nitrogen-Enhanced Stainless Steel

2017

Sensors and Materials

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The problem of stress corrosion cracking (SCC), which causes sudden failure of metals subjected to stress in a high-temperature, high-pressure water environment, is studied. Acoustic emission (AE) monitoring is a promising method for detecting the initiation and propagation of SCC. In this study, pencil-lead breaks are used as AE signal sources to first validate the parameters for the verification of the finite element modeling of microcracking. Then, a simplified fracture propagation model of low-carbon nitrogen-enhanced (316LN) stainless steel is established on the basis of moment tensor theory. Finally, the inner connection between the energy release rate of the AE source and the morphological aspect of crack formation is analyzed. The results of modal analysis show that the amount of energy released by the growing crack is linearly proportional to crack depth. Moreover, their frequency characteristics are almost unchanged from the results of analysis by fast Fourier transform. Therefore, SCC initiation and propagation in 316LN stainless steel can be evaluated by this detection method. Moreover, this analysis method based on the energy release rate of the AE source can also be extended to almost all solid materials and structural crack detection.

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Investigation of the fracture modes of red sandstone using XFEM and acoustic emissions

Cited by 93 publications

References 26 publications

Experimental and numerical studies on fracture characteristics of notched granite beams under cyclic loading and unloading

Experimental and numerical studies on fracture characteristics of notched granite beams under cyclic loading and unloading

Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States

Characteristic of Acoustic Emission Signal from Stress Corrosion Cracking in Low-Carbon Nitrogen-Enhanced Stainless Steel

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