Article
Engineering, Mechanical
Renliang Shan, Zhaolong Li, Chunhe Wang, Yonghui Wei, Yao Bai, Yan Zhao, Xiao Tong
Summary: By analyzing the asymmetrical deformation mechanism and stability control technology of the rock surrounding the near-fault roadway (NFR), it was found that the size and distribution of the deviatoric stress and plastic zone are determined by the ratio K of the maximum principal stress to minimum principal stress and the deflection angle alpha of maximum principal stress. Comparison with field measurements revealed the asymmetric deformation mechanism of NFR under the influence of mining activities.
ENGINEERING FAILURE ANALYSIS
(2021)
Article
Green & Sustainable Science & Technology
Yapeng Chen, Tong Wu, Xiaoshi Yan, Shang Shi, Jianyong Li, Jinyu Dong
Summary: Based on a typical project in an altered rock area, this study conducted numerical simulations using FLAC(3D) software to analyze the changes in stress, deformation, and plastic zone of the surrounding rock during unsupported and supported excavation of a water transfer tunnel. The results showed that the tunnel surrounding rock was affected by alteration to varying degrees, with compressive stress concentration at the bottom of the chamber in the unsupported state. The displacement at the bottom and side walls of the chamber increased significantly with the depth of alteration, and the plastic zone of the surrounding rock expanded. The adoption of support measures effectively controlled the stress, deformation, and plastic zone of the tunnel surrounding rock. The results can serve as a reference for similar projects in altered rock areas.
Article
Engineering, Mechanical
Hao Wu, Meng Huang, Yiping Xia, Xuewen Li, Rengeng Li, Chenglu Liu, Weimin Gan, Tiqiao Xiao, Lin Geng, Qing Liu, Guohua Fan
Summary: In this study, the presence of the interfacial stress-affected zone (ISAZ) was confirmed and the stress evolution process of Ti/Al multi-layered composites was quantified using in situ high-energy X-ray diffraction and in situ neutron diffraction. The results showed that the ISAZ spanned 15 μm and remained unchanged regardless of the load and layer thickness. The mechanical properties of the model material were optimized when the Al layer thickness was nearly twice the ISAZ size of 15 μm.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Construction & Building Technology
Yaocai Ma, Aizhong Lu, Hui Cai, Xiangtai Zeng
Summary: An analytical solution is proposed for studying the plastic zones developed around two circular tunnels with unequal size excavated in intact rock governed by the Mohr-Coulomb yield criterion. The solution involves the use of conformal transformation to map the elastic-plastic interfaces on the physical plane onto an annulus on the image plane. A set of nonlinear equations involving mapping function coefficients is constructed, and the differential-evolution algorithm is used to solve these equations.
TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY
(2022)
Article
Engineering, Geological
Liangjie Gu, Xia-Ting Feng, Rui Kong, Chengxiang Yang, Qiang Han, Yuelin Xia
Summary: The excavation of deep hard rock tunnels can cause disturbances in the initial stress balance, leading to rockburst, spalling, and collapse. This study analyzes and summarizes engineering cases to divide the surrounding rock of deep tunnels into high-, medium-, and low-risk fracture zones and generalize the excavation stress paths of these zones. The study reveals that the stress difference caused by excavation stress paths determines the level of surrounding rock fracture. The research proposes a method for evaluating the influence of excavation stress paths on rock fracture anisotropy. The findings provide insights into the mechanism of excavation stress paths affecting rock burst disasters in deep hard rock tunnels and offer guidance for selecting support schemes.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Environmental
Shaohua Du, Chunshun Zhang, Dawei Mao, Bo Ruan, Xianjing Lu
Summary: This paper presents a case study of the failure mechanisms and support design for a tailrace tunnel with poor lithology. A multilevel support system is proposed based on the failure mechanism, which effectively improves the principal stress state of the tunnel and controls the large deformation of the surrounding rock.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2022)
Review
Engineering, Chemical
Dawei Zhu, Guofeng Han, Honglan Zou, Mingyue Cui, Chong Liang, Fei Yao
Summary: In ductile reservoirs, the bottom-hole pressure of hydraulic fracturing is significantly higher than simulation, and the inferred fracture toughness from field data is orders of magnitude higher than that from laboratory testing. Excluding fluid effects, the fracture process zone (FPZ) at the fracture tip is passivated by plastic deformation, resulting in a wide and short hydraulic fracture. The size of FPZ is influenced by various factors and it exhibits size effect.
Article
Engineering, Geological
Junhong Huang, Xiaoqing Wei, Yi Luo, Hangli Gong, Tingting Liu, Xinping Li
Summary: This study investigated the deformation and failure of surrounding rock mass triggered by sudden changes of rock quality encountered in a tunnel excavation project, focusing on the geological disasters caused by fracture zones. The findings from a field case analysis of the Daliang Tunnel in China revealed the deformation profiles of the surrounding rock mass at different distances from the fracture zone. The relationship between the deformation of the surrounding rock mass in the fracture zone and the materials, length of advanced support, and excavation advance rate was also explored. The study emphasized the significance of controlling rock mass deformation in fracture zones.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Civil
Zeyu Li, Hongwei Huang, Mingliang Zhou, Dongming Zhang
Summary: This study uses the material point method (MPM) to simulate the failure responses of a rock tunnel face during excavation through the fault-fracture zone (FFZ). A numerical study was conducted to compare a physical model test and validate the feasibility of using the MPM in simulating tunnel face failure. The simulation results suggest that factors such as cohesion, friction angle, tunnel cover depth, and FFZ thickness significantly influence failure responses.
Article
Engineering, Environmental
Ziquan Chen, Zihan Zhou, Chuan He, Changwei Jiang, Bo Wang, Tiansheng Li
Summary: As China's transportation infrastructure expands westward, the construction of superlong deep-buried tunnels becomes more common in an area with active tectonic movements. However, the effects of faults formed by these movements on the distribution of geo-stress have not been studied systematically. This paper analyzes the disturbance influence of different factors using the Anderson model and Coulomb friction criterion, and establishes a viscoelastic-plastic damage constitutive model. The results show that all types of faults lead to a decrease in geo-stress within the fault-affected area, with strike-slip faults having the greatest effect.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2023)
Article
Engineering, Multidisciplinary
Yaocai Ma, Hehua Zhu, Wuqiang Cai, Chenlong Su, Xiangyang Wei
Summary: Based on the unified strength criterion, this study proposes an analytical solution to investigate the impact of tunnel axial stress on the development of failure zone around a circular tunnel. The proposed method handles the non-axisymmetric problem under a high and complex three-dimensional stress condition. The mechanical behavior of the rock mass follows an elastic-brittle-plastic model. The presented solution is compared with published analytical solutions, demonstrating its reliability and generality.
APPLIED MATHEMATICAL MODELLING
(2023)
Article
Materials Science, Multidisciplinary
Yupeng Wu, Yujie Zhang, Langquan Shui, Jinsong Wu, Ze Liu
Summary: In this study, the electron backscatter diffraction (EBSD) technique was used to identify grain boundaries (GBs) in a metal sheet surface, and the metal sheet was deformed via contact with a hard nanomold. The microstructure evolution and the influence of individual GBs on plastic deformation during nanomolding of crystalline Ag at different temperatures and stresses were investigated. The results revealed that diffusion-based mechanisms become dominant at temperatures above a critical value, and the GB-affected zone was measured to be several micrometers. Based on the decoded GB-based deformation mechanism, a prevalent deformation mechanism map can be experimentally constructed with high efficiency.
Article
Engineering, Mechanical
W. T. Li, Z. Y. Cai, H. Li, L. F. Peng, X. M. Lai, M. W. Fu
Summary: Coarse grains result in fewer voids on fracture surfaces and higher flow strength, while finer grains accelerate the occurrence of shear-dominated fracture and hinder normal tensile fracture. By introducing shear factor and size effect, the modified GTN-Thomason criterion predicts ductile fracture in micro-scaled plastic deformation and enhances understanding and prediction of ductile fracture.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Engineering, Geological
Liangjie Gu, Xia-Ting Feng, Rui Kong, Chengxiang Yang
Summary: In this study, the failure characteristics of Portuguese granite due to the interchange of principal stress directions are investigated. It is found that after the interchange, the rock's bearing capacity increases, anisotropic characteristics of deformation and fracture are interchanged, and the brittleness of the rock is enhanced. The study also explains the reasons for the change in failure mode and investigates the fracture mechanism and mode with the interchange of principal stress directions.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2023)
Article
Materials Science, Multidisciplinary
Boris Margolin, Victoria Shvetsova, Alexander Sorokin, Andrey Minkin, Natalia Pirogova
Summary: This study investigates the phenomenon of low temperature helium embrittlement in irradiated austenitic stainless steels, identifying strain-induced martensite and low cohesive strength of grain boundaries as the two key factors leading to this phenomenon. The research provides valuable insights for technology and materials design related to the LTHE phenomenon.
JOURNAL OF NUCLEAR MATERIALS
(2021)
Article
Mechanics
Chenxi Zhang, Diyuan Li, Jinyin Ma, Quanqi Zhu, Pingkuang Luo, Yuda Chen, Minggang Han
Summary: The influence of loading rate on the mode I fracture property of rocks has been extensively studied, but the rate-effect of dynamic mode II fracture is rarely reported. This study conducted a series of dynamic mode II fracture tests under a wide range of loading rates using the modified split Hopkinson pressure bar (SHPB) system. The results showed that the dynamic mode II fracture toughness increases with loading rate, and the fracture processes can be divided into multiple stages.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Engineering, Mechanical
Xiaoli Su, Diyuan Li, Quanqi Zhu, Jinyin Ma
Summary: This study investigated the effects of fatigue loads on hydraulic fracturing in granite under different stress states. The results showed that the amplitudes of cyclic load had a significant impact on fracture initiation pressure and fracture morphology. Higher amplitude disturbance in the intermediate principal stress direction resulted in lower breakdown pressure and wider fractures. Increasing disturbance frequency led to the generation of complex fatigue cracks, which could weaken the rock strength.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2023)
Article
Engineering, Geological
Jinyin Ma, Diyuan Li, Pingkuang Luo, Chenxi Zhang, Feihong Gao
Summary: The influence of bedding angles and pre-static loads on dynamic mechanical properties and damage mechanisms of layered sandstone under cyclic impact loads was investigated through a series of cyclic impact tests. It was found that the number of resisting cyclic impacts and the total dissipated energy of the sandstone showed an initial decline followed by an increase with the rising of the bedding angles. The damage evolution of the sandstone under cyclic impacts was described using a damage factor and the impact time curves could be divided into three stages. The damage threshold decreased as the pre-static load increased.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
Diyuan Li, Zida Liu, Quanqi Zhu, Chenxi Zhang, Peng Xiao, Jinyin Ma
Summary: This paper presents a quantitative method based on SEM images and deep learning to identify the mesoscopic failure mechanism of granite, which can determine the distribution of tensile and shear fractures on failure surfaces. The developed AlexNet models achieved high accuracy (96-98%) in identifying tensile and shear fracture surfaces. The results verified the application of the proposed method and its usefulness in understanding the failure mechanism of rock under uniaxial compression.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Mechanical
Quanqi Zhu, Diyuan Li, Jinyin Ma, Zhenyu Han, Xibing Li
Summary: The dynamic mixed mode I/II fracture properties of hard rock were investigated through split-Hopkinson pressure bar tests on cracked straight through Brazilian disc (CSTBD) diorite specimens. The fracture load and toughness for different crack angles or mode mixities were determined. The dynamic fracture process and crack mouth opening displacement (CMOD) were monitored, and the fractal and morphology characteristics of fracture surfaces were analyzed. The study found that the CMOD behavior is closely related to the force acting on the crack surface, and the allowable CMOD decreases with increasing crack angle. Stress-based and strain-based fracture criteria were introduced, and the GMTS criterion and EMTSN criterion showed the best prediction effect for fracture toughness and crack initiation angle respectively. Observation results showed that the macro fracture trajectories were controlled by the prefabricated crack angle, while the mode mixity had little impact on the meso-roughness and micro-morphology of the fracture surface. The fracture surface of CSTBD diorite specimen exhibited mixed tensile-shear cracks under dynamic load.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Materials Science, Multidisciplinary
Pingkuang Luo, Diyuan Li, Jinyin Ma, Aohui Zhou, Chengxi Zhang
Summary: In this study, a series of uniaxial compression tests were conducted on horizontal soft-hard interbedded composite rock-like material specimens with different thickness ratios. A parameter R was defined to characterize the strength properties of the specimens. The test results showed that the axial strength of the specimens decreased first and then tended to be constant with increasing R. The strain evolution and crack propagation process of the specimens were investigated using digital image correlation (DIC) technique. Meanwhile, a simplified mechanical model of laminated rock mass under uniaxial compression was established and showed consistency with the experimental results. This study reveals the failure mechanism of soft-hard interbedded rock mass at the bottom of the tunnel under the action of large horizontal stress after excavation.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Engineering, Geological
Peng Xiao, Diyuan Li, Guoyan Zhao, Quanqi Zhu
Summary: Rockburst in deep rock engineering poses a serious threat and is influenced by in-situ stress. The investigation found that the type of ground pressure hazard varies with the cover depth, including local spalling, rockburst, and large area collapse. The maximum horizontal principal stress indicates the regional in-situ stress field and is perpendicular to the strike of the regional metallogenic fault zone. The stress threshold for rockburst is 8 times the tensile strength of rock.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2023)
Article
Engineering, Geological
Jinyin Ma, Diyuan Li, Shaohua Du, Zhenyu Han, Pingkuang Luo, Junjie Zhao
Summary: Relaxation and rapid displacement loading tests were conducted on five types of rocks to explore the distinctions between subcritical crack growth (SCG) and dynamic fractures. The critical surface energy was determined by fitting a hyperbolic sine function to SCG velocities and mechanical energy release rates of the rocks. Through digital image correlation, the displacement field of the sample bottom surface was used to determine the specific SCG range and dimensions of the fracture process zone (FPZ).
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2023)
Article
Engineering, Geological
Chenxi Zhang, Diyuan Li, Jinyin Ma, Quanqi Zhu, Pingkuang Luo, Yuda Chen, Minggang Han
Summary: Investigating the dynamic shear fracture behavior of rocks under simulated geostress is crucial for deep rock engineering. Four groups of dynamic mode II fracture tests were conducted on granite specimens with different axial pre-forces using a coupled static-dynamic loading system. The results showed that the dynamic mode II fracture toughness increases with loading rate and decreases with pre-force ratio. An empirical model was established to describe the influence of pre-force and loading rate on fracture toughness. Deformation, damage, and fracture characteristics of rocks were analyzed based on surface deformation field. The study also proposed a novel relative shear velocity (RSV) to depict dynamic shear crack propagation.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Mechanical
Jinyin Ma, Diyuan Li, Hao Gong, Jingtai Jiang, Aohui Zhou, Pingkuang Luo
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Metallurgy & Metallurgical Engineering
Zi-da Liu, Di-yuan Li
Summary: This study considered intact rock properties to evaluate the failure modes of overstressed rock masses in deep rock excavation engineering. The developed hybrid model, JA-SVM, showed high accuracy and performance in predicting the failure modes compared to other machine learning models. The model can be used in the initial phases of deep underground projects to identify failure modes and prepare appropriate support measures based on estimation results.
JOURNAL OF CENTRAL SOUTH UNIVERSITY
(2023)
Article
Engineering, Mechanical
Zida Liu, Diyuan Li, Jianqiang Xia, Quanqi Zhu
Summary: In this study, the influence of flaw inclinations on the failure mechanism of fissured granite specimens was analyzed through a series of experiments. A quantitative method combining deep learning and scanning electron microscope was employed to identify the mesoscopic fracture mechanism of macroscopic cracks. The results indicated that the failure of fissured specimens was mainly caused by tensile stress and shear stress.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2024)
Article
Chemistry, Multidisciplinary
Diyuan Li, Zhen Peng, Quanqi Zhu, Jinyin Ma, Hao Gong
Summary: This study investigates the deformation mechanism and failure processes of floor heave in a layered rock tunnel through biaxial step-loading tests. It is found that continuous buckling fracturing progressively occurs at locations far away from the arching surface. The key location of internal surrounding rock deformation is determined, and the influence of interlayer properties and cover depth on bottom uplift is studied.
APPLIED SCIENCES-BASEL
(2023)
