Article
Chemistry, Physical
Guifeng Zhao, Lei Zhang, Bing Dai, Yong Liu, Zhijun Zhang, Xinyao Luo
Summary: This study investigated the effects of strain rate and crack intensity on the dynamic response of rock specimens. The results showed that the loading rate promoted the cracking failure of rock specimens and resulted in smaller average fragment sizes. In addition, the energy utilization efficiency decreased while the energy dissipation density increased with increasing strain rate.
Article
Mathematics, Interdisciplinary Applications
Guotao Yuan, Mingwei Zhang, Kai Zhang, Jun Wei, Zhuangcai Tian, Baolin Liu
Summary: In this study, the influence of pre-existing cracks on the dynamic mechanical behavior of cracked sandstone samples under impact loading was investigated using a two-dimensional particle flow code. The results demonstrate that crack density has the greatest impact on dynamic compressive strength, and a negative exponential relationship exists between crack density and dynamic mechanical properties. The presence of cracks affects the energy absorption rate and elastic energy storage capacity of the samples. The interaction of cracks weakens the dynamic elastic response of rock specimens, with increasing crack density and loading rate exacerbating this effect. This study provides valuable insights into the influence of cracks on rock dynamic mechanical behavior and has practical implications for rock engineering design and risk assessment.
COMPUTATIONAL PARTICLE MECHANICS
(2023)
Article
Multidisciplinary Sciences
Cong Ma, Chuanjie Zhu, Jingxuan Zhou, Jie Ren, Qi Yu
Summary: This article investigates the dynamic mechanical response of combined coal-rock and finds that the dynamic compressive strength and elastic modulus of the combined coal-rock are lower than those of single rock and coal, while the ultimate strain and strain rate are higher. The compressive strength and elastic modulus increase with increasing confining pressure, and the strain decreases accordingly. The dynamic stress-strain curve exhibits a double-peak feature at high strain rate, but not at low strain rate. The dynamic mechanical response of combined coal-rock is of guiding significance for maintaining the stability of the roadway and formulating support measures.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Geological
Zelin Yan, Feng Dai, Jianbo Zhu, Yuan Xu
Summary: This study systematically investigated the influences of pre-stress ratio, flaw inclination angle, and strain rate on the dynamic progressive cracking mechanism and energy evolution of multi-flawed rocks. The experimental results show that the dynamic/total strength generally increases with increasing strain rate, decreases with increasing flaw inclination angle, and exhibits complex changes with increasing pre-stress ratio.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Mechanical
Yue Zhai, Fandong Meng, Yubai Li, Yan Li, Ruifeng Zhao, Yunsheng Zhang
Summary: This study focuses on the micro-damage, macro-fracture characteristics, and dynamic properties of Tongchuan sandstone in northwest China after freeze-thaw. The results show that the impact loading has a greater effect on the rocks compared to freeze-thaw, and this effect weakens as the rocks soften. A new damage constitutive model considering various forms of dissipated energy has been proposed.
ENGINEERING FAILURE ANALYSIS
(2022)
Article
Engineering, Geological
Xing Li, Wei Yao, Chonglang Wang
Summary: Dynamic fragmentation is a primary fracture type for rock mass in rock engineering, and it is crucial for fragmentation optimization. Multiple dynamic loading leads to the production of more fragments and influences the size distribution, especially when the loading rate is lower. Multiple loading pulses decrease the mean fragment size and generate more fine grains compared to single loading pulses. Therefore, single dynamic compressive loading should be used when evaluating the dynamic fragmentation efficiency of rocks to avoid inaccurate fragmentation size analysis.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Geological
Quanqi Zhu, Xibing Li, Diyuan Li, Chunde Ma
Summary: This study investigates the static mechanical properties and failure characteristics of damaged rocks after impact under realistic in-situ stress. Dynamic triaxial compression tests were conducted on diorite with different strain rates and confining pressures. The results show that the dynamic peak stress, strain, elastic modulus, damage factor, and plastic deformation of diorite all increase with increasing strain rate. The increment in confining pressure leads to an increase in dynamic peak stress, elastic modulus, static residual strength, and brittleness. The post-peak behavior of dynamic stress-strain curves is divided into two classes according to the strain rate and fracture state of rocks under dynamic loading. The brittleness of damaged specimens generally decreases and drillability becomes much easier when the strain rate increases above a certain threshold. The fractal dimension of damaged specimens increases with confining pressure and decreases linearly with the increase of strain rate.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2022)
Article
Engineering, Geological
Peng Feng, Yuan Xu, Feng Dai
Summary: In rock specimens containing fissures, the type of cracks, strain rate, and symmetry of the fissures all have an impact on dynamic strength and energy dissipation under dynamic conditions. The dynamic strength of rock specimens significantly increases with increasing strain rate, while the dynamic elastic modulus remains constant regardless of loading rate. Additionally, the distribution of fragment size and energy dissipation density are also affected by the characteristics of the fissures.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Engineering, Civil
Qiangqiang Zheng, Ying Xu, Zhiqiang Yin, Feng Wang, Haijiang Zhang
Summary: This study aims to investigate the dynamic mechanical properties, strain field, energy evolution, and progressive cracking of damaged sandstone under impact loading. The experimental results show that the energy dissipation density ratio, scale of the initial central crack, strain, and level of rock fragmentation in the vicinity of the bar-sample interfaces all increase with increasing driving pressure or sandstone damage degree. These findings are of great significance to studying the mechanical responses of damaged rock and risk mitigation under dynamic catastrophes in rock engineering projects.
ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING
(2023)
Article
Engineering, Mechanical
Wenbing Fan, Junwen Zhang, Weimin Niu, Yang Zhang, Xukai Dong, Yulong Xing, Weigang Zeng
Summary: The mechanical characteristics and energy evolution law of sandstone with double cracks under dynamic load were investigated using SHPB test system. The stress-strain curves and failure characteristics were obtained, and the effects of crack angle and impact pressure were analyzed. The results showed that the compressive strength of the specimen initially decreased and then increased with increasing crack angle, while it increased gradually with increasing impact pressure. Under dynamic loading, the failure mode changed from tensile failure to shear failure and then to tensile failure as the crack angle increased. The fractal dimension increased with increasing impact pressure, and increased and then decreased with increasing crack angle.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Engineering, Civil
Jingxuan Zhou, Chuanjie Zhu, Jie Ren, Ximiao Lu, Cong Ma, Ziye Li
Summary: The dynamic compression strength of rocks and bituminous coal is found to be much greater than the static compression strength, and increases linearly with the strain rate. The failure degree of the sample increases with the increase of dynamic loading, and the number of small-scale fragments after bituminous coal rupture is the largest due to its lower static compression strength compared to rocks.
GEOMECHANICS AND ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
Lei Liu, Yuan Wang, Huaming An
Summary: In this study, the fracture morphology and energy dissipation of granite subjected to high-temperature treatment were analyzed. The results showed that the temperature had a significant impact on the fragmentation, transmitted energy, and dissipated energy of the granite, and a quadratic correlation existed between the damage factor and temperature.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Engineering, Geological
Jiadong Qiu, Heping Xie, Jianbo Zhu, Jun Wang, Jianhui Deng
Summary: This study investigates the influence of joint distribution on the dynamic response of underground caverns through a series of experiments and numerical simulations. The results show that the joint has limited impact on the cavern when the dip angle is 0 degrees, 90 degrees, and 180 degrees, but becomes significant at 56 degrees and 134 degrees. Different joint distributions can also cause four types of rockbursts in the cavern, and the displacement changes of surrounding rocks can indicate the stability of the cavern.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2023)
Article
Engineering, Mechanical
Runze Cai, Jize Mao, Hui Qi, Jia Qu, Qingyong Guo
Summary: This paper investigates the cracking behavior of repaired concrete structures through notched dynamic semi-circular bend tests. The results show that both the dynamic fracture toughness and crack propagation speed of concrete increase linearly with the loading rate. A threshold value exists beyond which the crack speed stabilizes, and the notch depth has little influence on the fracture toughness. Cracks propagate along the aggregates and remain intact under low loading rates, but penetrate and roughen the fracture surface at higher loading rates. Repaired concrete structures exhibit greater energy dissipation and produce flying fragments with lower kinetic energy, providing protection against secondary damage.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Chemistry, Physical
Hui Lu, Yue Pan, Kang He, Fei Wang, Lei Gao, Shikun Pu, Erbing Li
Summary: Dynamic mechanical tests were conducted on Beishan deep granite specimens with different strain rates using the split Hopkinson pressure bar (SHPB) device to study their dynamic mechanical properties and damage evolution mechanism. An improved Zhu-Wang-ang (ZWT) dynamic constitutive model was established, and the relationship between strain rate and strain energy was investigated. The test results showed a linear correlation between peak stress and strain rate, with a dynamic deformation modulus of 152.58 GPa for Beishan granite. The dissipation energy per unit volume and energy ratio increased with strain rate, while the dissipation energy per unit volume increased exponentially. There was a consistent relationship between the damage degree of granite specimens and the dissipation energy per unit volume, but not a one-to-one correspondence with the strain rate. To consider the damage, the principal structure of the element combination model was improved and simplified using the ZWT dynamic constitutive model, and the dynamic damage evolution equation of Beishan granite was established by considering the damage threshold.
Article
Engineering, Geological
Hongbo Du, Feng Dai, Mingdong Wei, Ang Li, Zelin Yan
Summary: The study finds that static confining pressure and dynamic loading rate enhance the load-carrying capacity of rocks, but the shear component limits the dynamic peak stress. With an increase in static confining pressure, the failure surface expands outward, while the compressive deformation modulus of rocks decreases with increasing shear component. The fragmentation behavior of rocks is restricted by static confining pressure and the shear component of dynamic loading, leading to a change in failure pattern as specimen inclination angle and static confining pressure increase.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
Ruochen Jiang, Feng Dai, Yi Liu, Ang Li
Summary: This study developed a microseismic (MS) location method using the fast marching method (FMM) and a second-order difference approach, which was validated through numerical experiments and successfully applied to locate blasting activities and MS events. The method significantly reduced location errors, providing a more accurate rock fracture location.
Article
Engineering, Geological
Peng Feng, Yuan Xu, Feng Dai
Summary: In rock specimens containing fissures, the type of cracks, strain rate, and symmetry of the fissures all have an impact on dynamic strength and energy dissipation under dynamic conditions. The dynamic strength of rock specimens significantly increases with increasing strain rate, while the dynamic elastic modulus remains constant regardless of loading rate. Additionally, the distribution of fragment size and energy dissipation density are also affected by the characteristics of the fissures.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Engineering, Geological
Ruochen Jiang, Feng Dai, Yi Liu, Ang Li, Peng Feng
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Mechanics
Zelin Yan, Feng Dai, Yi Liu, Ang Li, Hongbo Du
Summary: This study numerically investigates the rate-dependent progressive cracking behaviors of single-flawed rock specimens under different strain rates. The results show that the progressive cracking behaviors of rock specimens exhibit evident changes with increasing strain rates.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Engineering, Multidisciplinary
Ruochen Jiang, Feng Dai, Yi Liu, Ang Li
Summary: A new discriminant method is developed to automatically recognize Microseismic (MS) and blasting signals based on their time-frequency spectrum characteristics, providing more reliable data for MS monitoring analysis and reducing the impact of operators' subjectivity.
Article
Geosciences, Multidisciplinary
Weigang Shen, Tao Zhao, Feng Dai
Summary: This study investigates the influence of particle size on the buffering efficiency of a soil cushion layer through experimental and numerical tests. It is found that particle size can significantly affect the impact force, especially in high-velocity impacts. These findings offer insights for designing effective soil cushion layers for protection structures.
Article
Instruments & Instrumentation
Youzhen Li, Feng Dai, Wei You, Yi Liu
Summary: Understanding the fracture behavior of brittle rocks under dynamic mixed mode I/II loading is important for rock engineering structures. This study introduces a novel experimental method to investigate this fracture behavior, showing significant loading rate dependence of dynamic fracture toughness. The results demonstrate the feasibility and reliability of the method, revealing deviations in fracture path under mixed mode loading compared to pure mode loading.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Engineering, Geological
Quanbo Luo, Feng Dai, Yi Liu, Mengtan Gao, Zongchao Li, Ruochen Jiang
Summary: This study focuses on the potential impact of large velocity pulses during earthquakes on buildings, extracting pulse parameters from the 1999 and 2018 earthquakes and evaluating their seismic response on structures. The results show that velocity pulses can cause severe damage to structures, and exceeding seismic design values in long-period spectral values can exacerbate the vulnerability of high-rise buildings to earthquakes.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Energy & Fuels
Xinying Liu, Feng Dai, Yi Liu, Pengda Pei, Zelin Yan
Summary: Research indicates that the dynamic tensile strength of naturally saturated specimens increases with loading rate, but decreases with pre-tension. Additionally, the dynamic strength of naturally saturated sandstone is lower than that of natural sandstone, with similar fracture behavior. Water effects on mechanical properties, water wedging effect, and Stefan effect explain the dynamic tensile behavior of rocks with static preload.
Article
Mechanics
Zelin Yan, Feng Dai, Yi Liu, Mingdong Wei, Wei You
Summary: This study investigates the progressive failure process of flattened Brazilian disc (FBD) specimen using digital image correlation technique and proposes a modified calculation method to determine mode-I fracture toughness KIC. Additionally, the cracking nature of secondary cracks and the second rise of loading force induced by compressionshear failure near the flattened ends of the FBD specimen are identified. These findings contribute to a better understanding of the progressive fracture mechanism of FBD specimens and enhance the accuracy of KIC calibration by FBD testing method.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Engineering, Geological
Zelin Yan, Feng Dai, Jianbo Zhu, Yuan Xu
Summary: This study systematically investigated the influences of pre-stress ratio, flaw inclination angle, and strain rate on the dynamic progressive cracking mechanism and energy evolution of multi-flawed rocks. The experimental results show that the dynamic/total strength generally increases with increasing strain rate, decreases with increasing flaw inclination angle, and exhibits complex changes with increasing pre-stress ratio.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Mechanical
Zhiheng Wang, Yong Li, Weibing Cai, Weishen Zhu, Weiqiu Kong, Feng Dai, Chen Wang, Kai Wang
Summary: This study investigated the initiation mechanism of microcracks in fractured rock mass from the perspective of micromechanics, establishing macro-micro criteria to determine and distinguish the properties and types of cracks. It was found that the stress state of rock particles determines the type and propagation direction of cracks, allowing for an effective analysis of the initiation mechanism of different types of cracks and their propagation trends.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2021)
Article
Engineering, Mechanical
Mingdong Wei, Feng Dai
Summary: Laboratory-scale experiments were conducted on mixed-mode I/II fracture of non-oriented columnar saline ice, showing that temperature and loading conditions significantly influence the fracture behavior of ice. The results demonstrated that T-stress plays a crucial role in mixed-mode fracture of ice, with both trans- and inter-granular crack growth observed under different testing conditions.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2021)
Article
Construction & Building Technology
Ang Li, Feng Dai, Yi Liu, Hongbo Du, Ruochen Jiang
Summary: A novel dynamic method is proposed for evaluating the stability of high sidewalls subjected to flexural-toppling by integrating derived criterion, continuum modelling and microseismic data. The study defines a geo-mechanical model for analyzing toppling rock strata on high sidewalls and deduces potential energies equations using the Rayleigh-Ritz method. A quantitative stability evaluation methodology is presented considering progressive failure and the influence of fractures along bedding planes.
TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY
(2021)
