Experimental and numerical investigation of the fatigue behaviour and crack evolution mechanism of granite under ultra-high-frequency loading

Zhou, Yu; Zhao, Dajun; Tang, Qiongqiong; Wang, Meiyan

doi:10.1098/rsos.200091

Cited by 21 publications

(11 citation statements)

References 51 publications

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“…Based on laboratory simulation tests, some researchers have carried out crack propagation studies of samples with different loading rates and crack angles. It is concluded that the loading rate can change the crack propagation mode, and the crack angle affects the crack initiation position of samples [4][5][6][7][8]. Some researchers carried out uniaxial compression experiments on samples with natural cracks and divided the crack propagation into two stages: microscopic particle damage and macroscopic crack propagation.…”

Section: Introductionmentioning

confidence: 99%

Oblique Crack Propagation of Brittle Rock under Uniaxial Compression and Its Influencing Factors

Wang

Tian

2022

Wireless Communications and Mobile Computing

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With the development of infrastructure in China, the slope rock mass is affected by external forces such as roads. Tunnel excavation will cause a series of engineering problems, which are essentially caused by the instability caused by the propagation of internal cracks in the rock mass. At the same time, in practical engineering, the rock mass is formed through long-term geological structure, and its internal cracks have a variety of properties. Based on granite samples as the research object, two different angles of sample shapes, cylindrical and circular, are prefabricated. The uniaxial compression test is studied to analyze the law of inclined crack propagation in rock under uniaxial compression. Combined with the theory of fracture mechanics, the influence mechanism of crack inclination and sample shape on crack propagation in rock mass is discussed. The test results show that under uniaxial compression, the stress-strain curves of granite samples can be divided into four stages: compaction, elasticity, plasticity, and residual deformation. For the cylindrical sample, the crack initiation occurs at the tip. The compressive strength of the sample decreases with the increase in the prefabricated crack angle, and the crack initiation angle increases with the increase in the prefabricated crack angle. The fracture of the sample changes from shear slip failure to split shear failure of the penetrating rock mass with the increase in the crack angle. For the disk sample, the crack initiation location gradually increases from the tip to the middle with the increase in the crack angle, and the crack initiation angle increases with the increase in the crack angle. The peak load of the sample decreases first and then increases with the increase in the crack angle and is the minimum at 60°. The fracture mode of the sample is mainly tensile failure. When the crack dip angle is between 30° and 60°, the tensile and shear composite failure of the sample occurs, and the influence mechanism of crack dip angle and sample shape on the crack propagation path is analyzed. The research results have important theoretical significance for engineering design, construction, and stability maintenance.

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Section: Introductionmentioning

confidence: 99%

Oblique Crack Propagation of Brittle Rock under Uniaxial Compression and Its Influencing Factors

Wang

Tian

2022

Wireless Communications and Mobile Computing

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“…Flat-Joint Model and Parameter Calibration. PFC2D software is used to establish the discrete element model of ultrasonic vibration rock breaking by static load [29,30]. To solve the problems of the low ratio of unconfined compressive strength to tensile strength and low internal friction angle in PFC2D, a new bonding model called the flat-joint model (FJM) is adopted in this paper.…”

Section: Discrete Element Simulationmentioning

confidence: 99%

Experimental and Simulation Study on Breaking Rock under Coupled Static Loading and Ultrasonic Vibration

Zhao

Zhang

et al. 2022

Shock and Vibration

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In recent years, ultrasonic vibration rock-breaking technology has aroused great interest in tunnel excavation and underground mineral. To apply this technology to practical engineering, it is necessary to compare the difference between cumulative damage and crack propagation of rock under static load and ultrahigh frequency alternating load. Numerical simulation and laboratory experimental methods were used in this paper to study the damage and fracture characteristics of rock under static loading and ultrasonic vibration. The variation laws of rock infrared temperature characteristics, porosity and compressive strength under different ultrasonic static loads were studied. The discrete element model of rock under ultrasonic vibration was established, and the numerical simulation was carried out by PFC2D software. We designed the ultrasonic rotary drilling device to verify the drilling effect. The process and mechanism of rock fragmentation under static load and ultrasonic vibration load were analyzed from the perspective of energy. Numerical simulation and experimental results showed that the combination of static load and ultrasonic vibration accelerates the failure speed of rock sample. The thermal infrared temperature characteristic test showed that the rock-breaking process under ultrasonic load and static load has three stages: stage I, elastic deformation and the temperature rises linearly; stage II, the development of microcrack and the temperature is further increased uniformly, and stage III, macrobreaking and rock chips falling off, and the temperature fluctuates sharply. There is a minimum threshold value for the promotion of static loading to break rock by ultrasonic vibration. Only when the static load is greater than 200 N, the crack propagation will occur in the rock sample. At this time, with the increase of static load, the crack propagation will further intensify, and the rock-breaking effect is more obvious. Under the same weight on bit (WOB), the penetration of rotary ultrasonic drilling can be increased by 13.93% ∼ 38.11% compared with conventional rotary drilling.

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“…Based on the above analysis, eight influencing factors related to periodic displacement are obtained. The correlation between periodic displacement and external triggering factors is analyzed based on the gray relational grade (GRG) theory [34][35][36][37][38][39][40][41][42][43][44][45][46][47]. According to the GRG theory, when the discrimination coefficient is 0.5, if the relational degree value corresponding to the influence factor is greater than or equal to 0.8, it means that the two are closely related.…”

Section: The External Influencing Factorsmentioning

confidence: 99%

Application of GWO-ELM Model to Prediction of Caojiatuo Landslide Displacement in the Three Gorge Reservoir Area

Zhang

Chen²,

Zhang

et al. 2020

Water

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In order to establish an effective early warning system for landslide disasters, accurate landslide displacement prediction is the core. In this paper, a typical step-wise-characterized landslide (Caojiatuo landslide) in the Three Gorges Reservoir (TGR) area is selected, and a displacement prediction model of Extreme Learning Machine with Gray Wolf Optimization (GWO-ELM model) is proposed. By analyzing the monitoring data of landslide displacement, the time series of landslide displacement is decomposed into trend displacement and periodic displacement by using the moving average method. First, the trend displacement is fitted by the cubic polynomial with a robust weighted least square method. Then, combining with the internal evolution rule and the external influencing factors, it is concluded that the main external trigger factors of the periodic displacement are the changes of precipitation and water level in the reservoir area. Gray relational degree (GRG) analysis method is used to screen out the main influencing factors of landslide periodic displacement. With these factors as input items, the GWO-ELM model is used to predict the periodic displacement of the landslide. The outcomes are compared with the nonoptimized ELM model. The results show that, combined with the advantages of the GWO algorithm, such as few adjusting parameters and strong global search ability, the GWO-ELM model can effectively learn the change characteristics of data and has a better and relatively stable prediction accuracy.

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Experimental and numerical investigation of the fatigue behaviour and crack evolution mechanism of granite under ultra-high-frequency loading

Cited by 21 publications

References 51 publications

Oblique Crack Propagation of Brittle Rock under Uniaxial Compression and Its Influencing Factors

Oblique Crack Propagation of Brittle Rock under Uniaxial Compression and Its Influencing Factors

Experimental and Simulation Study on Breaking Rock under Coupled Static Loading and Ultrasonic Vibration

Application of GWO-ELM Model to Prediction of Caojiatuo Landslide Displacement in the Three Gorge Reservoir Area

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