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
Zelin Yan, Feng Dai, Yi Liu, Youzhen Li, Wei You
Summary: This study investigates the mechanical properties and fracturing behaviors of flawed rocks under combined static-dynamic loading. The results show that dynamic strength, total strength, and deformation modulus decrease with increasing flaw intensity and pre-stress ratio. The progressive fracturing behaviors are analyzed and it is found that rock specimens tend to fail into compression-shear mixed failure patterns.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
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
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, Geological
Peng Feng, Jiachen Zhao, Feng Dai, Mingdong Wei, Bo Liu
Summary: This study experimentally investigated the mechanical properties of conjugate-flawed rock specimens under coupled static-dynamic compression, and found that the coupled compressive strength and dynamic elastic modulus of the specimens showed remarkable loading rate dependence. The results also demonstrated that higher static pre-stress and strain rate could induce changes in mean fragment size and fractal dimension of the specimens, impacting their distribution of broken fragments. Additionally, the study discussed the failure modes of the specimens under different conditions, such as tensile failure at low strain rates and shear failure at high strain rates.
Article
Geochemistry & Geophysics
Hongbo Du, Haoran Wang, Peng Feng, Renjie Tian, Yi Wang
Summary: Preexisting fissures significantly affect the mechanical responses of rocks under coupled static-dynamic loads. The coupled dynamic strength of fissured rocks increases with the applied strain rate, while the elastic modulus does not depend on the loading rate. Fissured sandstone has the highest strength under a lower static prestress, and the failure modes change with the dynamic strain rate. Higher static prestress leads to greater energy dissipation density and efficiency.
Article
Engineering, Geological
Wei You, Feng Dai, Yi Liu
Summary: Accurately characterizing the mechanical responses and cracking mechanism of confined fractured rocks under coupled static-dynamic loading is crucial for underground engineering construction. The study investigates the behavior of single-flawed specimens under different axial prestresses and strain rates using a modified SHPB system. The results show that both dynamic strength and total strength are positively correlated with strain rate, with dynamic strength exhibiting higher sensitivity under higher axial prestress. The failure pattern also changes from single diagonal failure to X shaped conjugated failure as axial prestress increases.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2022)
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
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
Chemistry, Physical
Guang Li, Shuaiqi Liu, Rong Lu, Fengshan Ma, Jie Guo
Summary: This study conducted coupled static and dynamic load tests on granite specimens using a modified SHPB apparatus, and analyzed the fracturing process and damage evolution of the specimens using 3D-DIC technology. The results showed that there was no compaction stage in the stress-strain curve under combined dynamic and static loading, and the dynamic strength of the specimens was influenced by the static pressure and crack inclination angle. The change in axial compression had a significant influence on the failure mode, transitioning from shear-tensile failure to shear failure.
Article
Materials Science, Multidisciplinary
Jianxun Zhang, Yinggang Miao, Qinghua Qin, Tongqing Lu, Yang Ye, He He, Jikun Wang, Hua Li
Summary: This study investigates the mechanical behaviors of hydrogels under the influence of different fluid compositions through static and dynamic experiments. It is found that immersion in FeCl3 solution can increase the strength of hydrogels.
MECHANICS OF MATERIALS
(2021)
Article
Chemistry, Physical
Lei Zhang, Zhijun Zhang, Ying Chen, Yong Liu, Xinyao Luo, Bing Dai
Summary: During the excavation of underground projects, the rock masses experience both dynamic loads from the excavation activities and static loads from the subsequent support system. This study investigated the influence of inclination angle on the strength, strain, and fractal properties of granite rock samples under dynamic and static loading conditions. The results provide valuable insights for ensuring the safety of deep mining operations.
Article
Chemistry, Multidisciplinary
Xuan Xu, Li-Yuan Chi, Jun Yang, Qi Yu
Summary: This study investigated the dynamic tensile fracture characteristics of two igneous rocks using the SHPB and high-speed camera. Rate-dependent effects on dynamic tensile strength were predicted using the incubation time criterion. Digital image correlation and image processing were utilized to analyze tensile strain distribution and fracture morphology, with statistical analysis revealing differences in fracture behaviors between the rocks. The findings provide valuable references for relevant research on dynamic splitting processes.
APPLIED SCIENCES-BASEL
(2021)
Article
Engineering, Geological
Hongbo Du, Feng Dai, Ang Li, Ruochen Jiang
Summary: In waterway regulation engineering, understanding the dynamic responses and failure mechanism of saturated rocks subjected to repetitive compression-shear impacting is of great significance. This study conducted tests on saturated and dry sandstone specimens using the split Hopkinson pressure bar apparatus. The results indicate that the loading rate and shear component have a negative influence on the bearing capacity of saturated sandstone, but also improve energy absorption and utilization.
ROCK MECHANICS AND ROCK ENGINEERING
(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
Engineering, Geological
Sixia Gong, Tao Zhao, Jidong Zhao, Feng Dai, Gordon G. D. Zhou
Summary: Slit dams are open-check barrier structures widely used in mountainous regions to resist the destructive impacts of granular flows. A numerical study using DEM showed that by adjusting relative post spacing and particle clump aspect ratio, the design of slit dams can be optimized to increase trapping efficiency.
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, 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)
Article
Mining & Mineral Processing
Wei You, Feng Dai, Yi Liu, Hongbo Du, Ruochen Jiang
Summary: This study introduces a numerical servo triaxial Hopkinson bar (NSTHB) to investigate the dynamic responses of rocks under a true triaxial stress state. The results indicate that the increase in intermediate principal stress leads to an increase in dynamic strength and elastic modulus of rocks, while the dynamic elastic modulus remains independent of the dynamic strain rate. Additionally, the study shows that the intermediate principal stress significantly affects the dynamic failure modes of rocks.
INTERNATIONAL JOURNAL OF MINING SCIENCE AND TECHNOLOGY
(2021)
