Fracture Evolution Analysis of Rock Bridges in Hard Rock with Nonparallel Joints in True Triaxial Stress States

Zhang, Yan; Chen, Guoqing; Wang, Zhaofeng; Liu, Ding

doi:10.1007/s00603-022-03117-x

Cited by 6 publications

(4 citation statements)

References 65 publications

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“…These waves propagate to the surface of the specimen, where acoustic emission sensors fixed on the surface can detect the surface changes of the specimen. The acoustic emission is then manifested in forms such as the number of ring counts or energy [45,46].…”

Section: Acoustic Emission Characterization 41 Acoustic Emission Char...mentioning

confidence: 99%

Experimental Study on Energy Evolution and Acoustic Emission Characteristics of Fractured Sandstone under Cyclic Loading and Unloading

Xie,

Sun,

Sheng

2024

Applied Sciences

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To investigate the dynamic response of fractured rock under cyclic loading and unloading, a WHY-300/10 microcomputer-controlled electro-hydraulic servo universal testing machine was used to conduct uniaxial cyclic loading and unloading tests. Simultaneously, acoustic emission (AE) and a CCD high-speed camera were employed to monitor the fracturing characteristics of sandstone. The mechanical properties, energy evolution, AE characteristics, and deformation of 45° sandstone were analyzed. The results indicate that as the load cycle level increases, both the elastic modulus and deformation modulus exhibit a “parabolic” increase, with a rapid rise initially and a slower rate of increase later. The damping ratio generally shows a decreasing trend but tends to rise near the peak load. The total energy, elastic energy, dissipated energy, damping energy, and damage energy all follow exponential function increases with the load level. The b-value fluctuates significantly during the stable crack propagation phase, unstable crack propagation phase, and peak phase. When the FR (Felicity ratio > 1), the rock is relatively stable; when the FR (Felicity ratio < 1), the rock gradually extends towards an unstable state. The Felicity ratio can be used as a predictive tool for the precursors of rock failure. Shear fractures dominate during the compaction and peak phases, while tensile fractures dominate during the crack propagation phase, ultimately leading to a failure characterized by tensile fracture. High-speed camera observations revealed that deformation first occurs at the tips of the prefabricated cracks and gradually spreads and deflects toward the ends of the sandstone. This study provides theoretical support for exploring the mechanical behavior and mechanisms of fractured rock under cyclic loading and unloading, and it has significant practical implications.

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Section: Acoustic Emission Characterization 41 Acoustic Emission Char...mentioning

confidence: 99%

Experimental Study on Energy Evolution and Acoustic Emission Characteristics of Fractured Sandstone under Cyclic Loading and Unloading

Xie,

Sun,

Sheng

2024

Applied Sciences

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“…The occurrence of rockburst is related to various factors, such as complex geological conditions, cavern layout, and excavation disturbance. Previous studies on rockburst phenomena [17][18][19][20][21][22] have led to a relatively deep understanding of the diversity of rockburst, the mechanism of occurrence, and the relationship between rockburst occurrence and the physical and mechanical properties of surrounding rock. Many effective methods for controlling rockburst have been proposed by summarizing the mechanism and evaluation methods of rockburst.…”

Section: Mechanism and Control Measures Of Rockburstmentioning

confidence: 99%

Numerical Simulation Analysis Method for Rockburst Control in Deeply Buried Caverns

Zhan,

Liu,

Xiao

et al. 2023

Applied Sciences

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Investigating the mechanism and measures of controlling rockburst in deeply buried underground caverns is a prerequisite for ensuring the safety of personnel, reducing the damage to construction equipment caused by the rockburst, and making the project economical and efficient. Efficient analysis methods for evaluating rockburst control in underground caverns are crucial for qualitatively selecting rockburst control methods and quantifying the effectiveness of rockburst measures. Based on the mechanism of energy accumulation in rock mass and the occurrence of rockburst as well as the active methods for controlling rockburst, we propose a mathematical model for simulating borehole stress relief using implicit borehole elements. In this modeling approach, we combine vector superposition in different borehole directions to analyze the effect of borehole stress relief on improving the external environment of the rock mass. Based on the interaction between the anchor support and the surrounding rock as well as the implementation of passive rockburst control measures, we propose a mathematical model that utilizes the implicit anchor column elements to simulate the reinforcement of the surrounding rock with anchors. By combining system anchors into arches and suspending anchors to reinforce the caverns, the overall stiffness of the surrounding rock can be improved and the stress accumulation can be alleviated. The coordinated deformation between the surrounding rock and the anchor provides support to prevent the rockburst. The effects of two rockburst control measures, borehole releasement and anchor reinforcement, are analyzed using both the strength theory and the energy theory. Engineering examples are provided to illustrate that the use of borehole elements to simulate local stress relief can effectively improve the external environment of the rock mass to control the occurrence of rockburst. Additionally, the mechanism of using anchor column elements in combination with the surrounding rock elements to enhance the overall stiffness of the rock mass and prevent rockburst is explored.

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“…For example, in tectonically active regions, a substantial quantity of elastic strain energy accumulates in the highly stressed rock mass. The excavation unloading can result in the sudden release of stored elastic energy, causing instability failure, which is categorized as energy-accumulated-induced rock mass instability failure [3][4][5]. In addition, due to the true triaxial stress conditions (σ 2 > σ 3 ), hard rock failure and related disaster issues under deep true triaxial stress (σ 2 > σ 3 ) are extremely complex [6].…”

Section: Introductionmentioning

confidence: 99%

Thermal Infrared Precursor Information of Rock Surface during Failure Considering Different Intermediate Principal Stresses

et al. 2023

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Rock failure generally leads to serious consequences, and it is significant to obtain the precursor information prior to failure using associated techniques. Thus, it is essential to acquire and probe the relevant precursor information. In this study, true triaxial tests are performed on red sandstone specimens under varying intermediate principal stress conditions. The thermal infrared image evolution and the temperature-induced change characteristics of rock failure are also analyzed using infrared thermal imaging technology. In addition, with the assistance of a high-speed photography technique, these characteristics during the true triaxial compression and unloading processes are systematically investigated to determine how the intermediate principal impacts on thermal image, temperature, and fracture propagation. Finally, the evolution mechanism of the specimens is summarized, and a non-contact thermal infrared rock failure precursor indicator is proposed, which can give significant advance notice of rock collapse before the abnormal temperature change. The results show that there exist thermal infrared temperature precursors, thermal image precursors, and rapid development of rock macroscopic cracks before rock failure. Abnormal thermal images are prior to the abnormal temperature changes. As the intermediate principal stress increases, thermal abnormalities will change accordingly. Both temperature changes and thermal image anomalous patches can be utilized as precursor information of rock collapse, and the mechanism and specific information of thermal infrared failure precursors can be preliminarily determined in time and space. Our results can function as a significant frame of reference for the analysis and prevention of rock failure due to sudden instability.

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Fracture Evolution Analysis of Rock Bridges in Hard Rock with Nonparallel Joints in True Triaxial Stress States

Cited by 6 publications

References 65 publications

Experimental Study on Energy Evolution and Acoustic Emission Characteristics of Fractured Sandstone under Cyclic Loading and Unloading

Experimental Study on Energy Evolution and Acoustic Emission Characteristics of Fractured Sandstone under Cyclic Loading and Unloading

Numerical Simulation Analysis Method for Rockburst Control in Deeply Buried Caverns

Thermal Infrared Precursor Information of Rock Surface during Failure Considering Different Intermediate Principal Stresses

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