This page has only limited features, please log in for full access.
DIYUAN LI was born in Xinshao, China, in 1981. He received the B.S., M.S., and Ph.D. degrees from Central South University, Changsha, China. He is currently a Professor of Central South University. His research interests include rock mechanics, filling theory, blasting vibration, and fluid–solid coupling.
The semi-circular bend (SCB) specimen is widely used to measure fracture toughness of brittle materials such as rock. In this work, the stress field, fracture process zone (FPZ), and crack propagation velocity of SCB specimen are analyzed during the fracture process of rock specimens. The FPZ of specimen is obtained by experimental and numerical methods under a three-point bend test. The stress concentration zones of specimen present a heart shape at peak load points. FPZ forms before macro fracture occurs. The macro fracture form inside FPZ in a post-peak region of a load–displacement curve. The crack propagation process of specimen include two stages, namely the rapid crack initial development stage, and the final crack splitting stage. The maximum crack propagation velocity of specimen is about 267 m/s, and the average crack propagation velocity is about 111 m/s.
Peng Xiao; Diyuan Li; Guoyan Zhao; Meng Liu. Experimental and Numerical Analysis of Mode I Fracture Process of Rock by Semi-Circular Bend Specimen. Mathematics 2021, 9, 1769 .
AMA StylePeng Xiao, Diyuan Li, Guoyan Zhao, Meng Liu. Experimental and Numerical Analysis of Mode I Fracture Process of Rock by Semi-Circular Bend Specimen. Mathematics. 2021; 9 (15):1769.
Chicago/Turabian StylePeng Xiao; Diyuan Li; Guoyan Zhao; Meng Liu. 2021. "Experimental and Numerical Analysis of Mode I Fracture Process of Rock by Semi-Circular Bend Specimen." Mathematics 9, no. 15: 1769.
An understanding of the fracture behavior and subcritical crack propagation of hard rock under different temperatures is necessary for the design and stability of nuclear waste disposal projects. The aim of this study was to understand the thermal effect on the fracture behavior of granite, which had been heated at 25 (untreated), 100, 200, 400, and 600 °C, respectively. A series of uniaxial compressive tests and double-torsion tests were performed on granite specimens. The three-dimensional digital image correlation technique was used to investigate the strain evolution and fracture pattern in granite specimens during subcritical crack propagation. According to the results, the uniaxial compression strength, Young’s modulus and fracture toughness of the granite specimens increased and then decreased with an increase in treatment temperature. These parameters dropped sharply as the treatment temperature exceeded 400 °C, mainly because of the thermally-induced destruction of the quartz crystal structure and a generation of wider intergranular fractures. A comparison of the subcritical crack length by theoretical calculations and experimental observations from digital image correlation showed that the two values were consistent. At a treatment temperature of 400 °C and 600 °C, the velocity of the subcritical crack propagation was accelerated, so the length of the subcritical crack during the relaxation test was 4.14 times and 5.25 times that at 25 °C, respectively. The subcritical crack growth and fracture process of the double-torsion tests were visible by the three-dimensional digital image correlation system. A subcritical crack growth index (n) can be used to characterize the susceptibility of the subcritical crack propagation in rock relaxation tests, which helps to evaluate the long-term stability of nuclear waste disposal projects.
Diyuan Li; Jinyin Ma; Qianrong Wan; Quanqi Zhu; Zhenyu Han. Effect of thermal treatment on the fracture toughness and subcritical crack growth of granite in double-torsion test. Engineering Fracture Mechanics 2021, 253, 107903 .
AMA StyleDiyuan Li, Jinyin Ma, Qianrong Wan, Quanqi Zhu, Zhenyu Han. Effect of thermal treatment on the fracture toughness and subcritical crack growth of granite in double-torsion test. Engineering Fracture Mechanics. 2021; 253 ():107903.
Chicago/Turabian StyleDiyuan Li; Jinyin Ma; Qianrong Wan; Quanqi Zhu; Zhenyu Han. 2021. "Effect of thermal treatment on the fracture toughness and subcritical crack growth of granite in double-torsion test." Engineering Fracture Mechanics 253, no. : 107903.
Taking the “11.28” rockburst occurred in the Jinping II Hydropower Station as the engineering background, the evolution mechanism of structure-type rockburst was studied in detail based on the particle flow code. The results indicate that the failure mechanism of structure-type rockburst includes a tensile fracture induced by tangential compressive stress and a shear fracture caused by shear stress due to overburdened loadings and shear slip on the structural plane. In addition, it is found that the differences between structure-type rockburst and strainburst mainly include (a) the distribution of the local concentrated stress zone after excavation, (b) the evolution mechanism, and (c) the failure locations. Finally, the influence of four factors on the structure-type rockburst are explored. The results show that (1) when the friction coefficient is greater than 0.5, the effect of structural plane is weakened, and the rock near excavation tends to be intact, the structural-type rockburst intensity decreases; (2) the dissipated and radiated energy in structural-type rockburst reduces with rockmass heterogeneity m; (3) the lateral pressure coefficient has a significant effect on the intensity of deep rock failure, specifically in the form of the rapid growth in dissipative energy; (4) and the structural-type rockburst is more pronounced at a structural plane length near 90 mm.
Chenxi Zhang; Diyuan Li; Shunchuan Wu; Long Chen; Jun Peng. Study on Evolution Mechanism of Structure-Type Rockburst: Insights from Discrete Element Modeling. Sustainability 2021, 13, 8036 .
AMA StyleChenxi Zhang, Diyuan Li, Shunchuan Wu, Long Chen, Jun Peng. Study on Evolution Mechanism of Structure-Type Rockburst: Insights from Discrete Element Modeling. Sustainability. 2021; 13 (14):8036.
Chicago/Turabian StyleChenxi Zhang; Diyuan Li; Shunchuan Wu; Long Chen; Jun Peng. 2021. "Study on Evolution Mechanism of Structure-Type Rockburst: Insights from Discrete Element Modeling." Sustainability 13, no. 14: 8036.
Permeability is a fundamental index that is closely related to rock damage in geotechnical engineering. In this study, dynamic triaxial compression tests were performed using a modified split Hopkinson pressure bar (SHPB) for a range of incident energies, confining pressures, and number of impacts to study the mechanical behavior and permeability evolution of sandstone after dynamic loading under realistic in-situ stress. The damage factor of rock before and after the impact was measured and calculated using a rock wave velocity measurement device, and the rock permeability was tested following the pulse-decay method with a MTS-815 testing system. The results show that the peak stress, strain, plasticity, damage, and permeability of sandstone all increase with increasing incident energy. Only the peak stress increases with increasing confining pressure, whereas the other physico-mechanical parameters decrease. The opposite result is obtained in response to an increased number of impacts. The dynamic stress–strain curves are categorized into classes I and II based on the post-peak behavior and fracture pattern. The quantitative relationships between energy, damage, and permeability are discussed. The absorbed energy per unit volume follows a negative exponential relationship with the damage factor and a positive linear relationship with the permeability enhancement index. The damage factor follows a positive exponential relationship with the permeability enhancement index. The permeability enhancement is mainly due to increased connectivity of the pores and channels in the rock caused by crack propagation and coalescence, and the rock damage and fracture are controlled by the absorbed energy. The mechanical behavior and permeability evolution of sandstone are determined from triaxial SHPB and triaxial permeability tests. The effects of incident energy, confining pressure, and impact number on the dynamic physico-mechanical properties are analyzed. The functional relationships between rock damage, permeability, and energy are obtained.
Quanqi Zhu; Diyuan Li; Wenjian Wang. Mechanical behavior and permeability evolution of sandstone with confining pressure after dynamic loading. Geomechanics and Geophysics for Geo-Energy and Geo-Resources 2021, 7, 1 -20.
AMA StyleQuanqi Zhu, Diyuan Li, Wenjian Wang. Mechanical behavior and permeability evolution of sandstone with confining pressure after dynamic loading. Geomechanics and Geophysics for Geo-Energy and Geo-Resources. 2021; 7 (3):1-20.
Chicago/Turabian StyleQuanqi Zhu; Diyuan Li; Wenjian Wang. 2021. "Mechanical behavior and permeability evolution of sandstone with confining pressure after dynamic loading." Geomechanics and Geophysics for Geo-Energy and Geo-Resources 7, no. 3: 1-20.
To deeply understand the failure characteristics of defective rock under actual stress condition, impact tests were conducted on prismatic granite containing two rectangular holes with different axial static pre-stresses by a modified split Hopkinson pressure bar (SHPB), and uniaxial compression tests were also carried out for comparison. Combined with digital image correlation (DIC), the dynamic damage and fracture process of specimens were observed by low-speed and high-speed cameras. Moreover, the energy evolution characteristics of specimens were analyzed to further understand the failure mechanism. The results indicate that the pre-stress has dual effects on the dynamic mechanical behavior of rock specimens, and the transition mechanism of the effect of pre-stress can be revealed by the elastic deformation limit. Observations show that the failure of specimens under different loads is caused by the growth of secondary cracks at hole corners. However, with the increase in pre-stress, the crack mode tends to shear and the strain localization tends to concentrate on sidewalls, resulting in severe rock bursting and extensive fracturing. Four coalescence modes around two rectangular holes were summarized: diagonal shear coalescence under static load, no coalescence under dynamic load, shear coalescence inside the middle rock bridge area under the pre-stress of 25–55% UCS, and indirect coalescence outside the rock bridge area under the pre-stress of 75% UCS. The specimen with the pre-stress of 75% UCS releases the internal strain energy during dynamic failure process, while the specimen with lower pre-stress absorbs the external impact energy. Finally, some insights are provided for deep rock engineering based on the test results.
Quanqi Zhu; Diyuan Li; Zhenyu Han; Peng Xiao; Bang Li. Failure characteristics of brittle rock containing two rectangular holes under uniaxial compression and coupled static-dynamic loads. Acta Geotechnica 2021, 1 -22.
AMA StyleQuanqi Zhu, Diyuan Li, Zhenyu Han, Peng Xiao, Bang Li. Failure characteristics of brittle rock containing two rectangular holes under uniaxial compression and coupled static-dynamic loads. Acta Geotechnica. 2021; ():1-22.
Chicago/Turabian StyleQuanqi Zhu; Diyuan Li; Zhenyu Han; Peng Xiao; Bang Li. 2021. "Failure characteristics of brittle rock containing two rectangular holes under uniaxial compression and coupled static-dynamic loads." Acta Geotechnica , no. : 1-22.
It is typical for rock material to be bi-modularity in terms of Young’s modulus and Poisson’s ratio. In other words, these values differ in compression (\(E_{{\text{c}}} ,\upsilon_{c}\)) and in tension (\(E_{{\text{t}}} {,}\upsilon_{{\text{t}}}\)). In this work, four kinds of rock materials (sandstone, marble, granite, basalt) were tested to study such bi-modularity behavior in uniaxial compression and in tension (Brazilian disc test). The compressive elastic constants were determined from uniaxial compression testing, while the tensile elastic constants were determined by an improved methodology using displacement measurement in both horizontal and vertical directions of points on the flat surface of a Brazilian disc. Digital image correlation (DIC) was used to monitor the strain and displacement field on the Brazilian disc surface. Validation of the reliability of the testing method is also carried out, and it is found that tensile cracks initiate at the disc center for all tested specimens. Then, the rationality of the determined tensile elastic constants is validated by comparison with the values obtained from the direct tensile tests. Finally, based on the experimental data, it is found that the values of \({{E_{{\text{t}}} } \mathord{\left/ {\vphantom {{E_{{\text{t}}} } {E_{{\text{c}}} }}} \right. \kern-\nulldelimiterspace} {E_{{\text{c}}} }}\) and \({{\upsilon_{{\text{t}}} } \mathord{\left/ {\vphantom {{\upsilon_{{\text{t}}} } {\upsilon_{{\text{c}}} }}} \right. \kern-\nulldelimiterspace} {\upsilon_{{\text{c}}} }}\) of each rock type are similar, except for marble. As the ratio of tensile to compressive strength increases, the value of \({{E_{{\text{t}}} } \mathord{\left/ {\vphantom {{E_{{\text{t}}} } {E_{{\text{c}}} }}} \right. \kern-\nulldelimiterspace} {E_{{\text{c}}} }}\) also appears to increase slightly. Lastly, the mechanism of bi-modular behavior of rock is discussed.
Diyuan Li; Bang Li; Zhenyu Han; Quanqi Zhu; Meng Liu. Evaluation of Bi-modular Behavior of Rocks Subjected to Uniaxial Compression and Brazilian Tensile Testing. Rock Mechanics and Rock Engineering 2021, 1 -15.
AMA StyleDiyuan Li, Bang Li, Zhenyu Han, Quanqi Zhu, Meng Liu. Evaluation of Bi-modular Behavior of Rocks Subjected to Uniaxial Compression and Brazilian Tensile Testing. Rock Mechanics and Rock Engineering. 2021; ():1-15.
Chicago/Turabian StyleDiyuan Li; Bang Li; Zhenyu Han; Quanqi Zhu; Meng Liu. 2021. "Evaluation of Bi-modular Behavior of Rocks Subjected to Uniaxial Compression and Brazilian Tensile Testing." Rock Mechanics and Rock Engineering , no. : 1-15.
A large fault fracture zone with about 100 m wide exists in Wuyue Pumped Storage Power station of China, where the low-strength and highly-fractured granite severely restricts the stability of the underground powerhouse. However, no relevant exploration has been made on its lithology to ensure the safety of the upcoming construction. To overcome this insufficiency, we present the most recent researches on the strength and deformation of the local granite. The local rock samples were obtained through field sampling from the exploratory adit PD1, and its deformation and strength properties depending on environmental conditions was thoroughly investigated, by mean of experimental and theoretical analysis. Primary attention is given to the prediction and engineering guidance of the proposed model upon the mechanical parameters and shear strength when considering the more extensive environmental variables, namely, dry densities and confining pressures. Experimental results show that the failure of remoulded soils with completely decomposed granite is characterized by bulging deformation in the middle without a visible failure surface, along with significant “volume-contraction”. Also, the influence of environmental variables on mechanical parameters is different, in particular peak strength and elastic modulus present highly linear correlation with the confining pressure and dry density. Additionally, based on the measurements, the proposed universal function law upon mechanical parameters and shear strength depending on environmental variables, compare well with experimental results for practical purposes. Our conclusions are useful to capture the deformation and strength behaviour and then put forward corresponding measures for the poor surrounding rock mass, especially those being highly decomposed, where the Wuyue Pumped Storage Power station is to be built shortly.
Shaohua Du; Diyuan Li; Chunshun Zhang; Dawei Mao; Bo Ruan. Deformation and strength properties of completely decomposed granite in a fault zone. Geomechanics and Geophysics for Geo-Energy and Geo-Resources 2021, 7, 1 -21.
AMA StyleShaohua Du, Diyuan Li, Chunshun Zhang, Dawei Mao, Bo Ruan. Deformation and strength properties of completely decomposed granite in a fault zone. Geomechanics and Geophysics for Geo-Energy and Geo-Resources. 2021; 7 (1):1-21.
Chicago/Turabian StyleShaohua Du; Diyuan Li; Chunshun Zhang; Dawei Mao; Bo Ruan. 2021. "Deformation and strength properties of completely decomposed granite in a fault zone." Geomechanics and Geophysics for Geo-Energy and Geo-Resources 7, no. 1: 1-21.
The identification of parameters that affect mining is one of the requirements in executive work in this field. Due to the dangers of flyrock, studying the role of the factors that affect it will be useful to control this serious environmental issue of blasting. In this research, using hybrid intelligence techniques, a new guide to investigate the parameters that affect the occurrence and characteristics of flyrock is presented. Hybrid models were improved based on five types of optimization algorithms, namely particle swarm optimization, artificial bee colony, the imperialist competitive algorithm, firefly algorithm (FA), and genetic algorithm. The process of designing the structure of the models was controlled under the fuzzy Delphi method. This filter helps to determine the most important factors that play a key role in the flyrock phenomenon and its accurate prediction. The best optimization technique was selected based on applying two popular performance indices, i.e., the root-mean-square error and coefficient of determination (R2). As a result, the best combination obtained was the FA-artificial neural network (ANN), which was able to provide the best optimization of the weights and biases of the ANN among all the proposed models. In addition, this system showed the lowest network error in the prediction of flyrock compared to other ANN-based models. The new combination (FA-ANN) can be used as a powerful and practical technique to predict the flyrock distance prior to blasting operations.
Diyuan Li; Mohammadreza Koopialipoor; Danial Jahed Armaghani. A Combination of Fuzzy Delphi Method and ANN-based Models to Investigate Factors of Flyrock Induced by Mine Blasting. Natural Resources Research 2021, 30, 1905 -1924.
AMA StyleDiyuan Li, Mohammadreza Koopialipoor, Danial Jahed Armaghani. A Combination of Fuzzy Delphi Method and ANN-based Models to Investigate Factors of Flyrock Induced by Mine Blasting. Natural Resources Research. 2021; 30 (2):1905-1924.
Chicago/Turabian StyleDiyuan Li; Mohammadreza Koopialipoor; Danial Jahed Armaghani. 2021. "A Combination of Fuzzy Delphi Method and ANN-based Models to Investigate Factors of Flyrock Induced by Mine Blasting." Natural Resources Research 30, no. 2: 1905-1924.
The permeability evolution of rock is essential in geotechnical engineering, which is related to seepage. A permeability evolution model, which is based on the wing crack propagation model and Darcy's law, is created for rock after dynamic load testing with confining pressures. It is assumed that permeability has two types: isotropic initial permeability and anisotropic microcrack-induced permeability. In this model, the wing crack length is associated with the absorption energy per unit volume of the rock specimen under dynamic loads, in accordance with the surface energy theory. Assuming that the initial crack families are evenly distributed, the contribution of each crack family to permeability in different directions is investigated. In this study, an expression of permeability, which is related to axial stress, confining pressure, and absorbed energy per unit volume, is obtained. Two groups of dynamic load testing with confining pressures of sandstone are conducted using a modified split Hopkinson pressure bar technique. In group A, the incident energy is a variable, whereas in group B, the confining pressure is a variable. After the dynamic load testing, the permeability of the sandstone specimens is measured using the pulse decay method on MTS 815. Owing to the limitations on the test equipment, only the permeability in the direction of the dynamic load is measured. The permeability obtained from the dynamic load testing is in good agreement with the permeability calculated by the model. In this model, the anisotropy of rock permeability is theoretically studied. The minimum microcrack-induced permeability in all directions is about 0.65 of the maximum permeability value. In summary, the model discussed here enables the prediction of the permeability of the rocks under dynamic impact and establishes the relationship between macro-mechanical parameters and micro-mechanical parameters. In addition, it provides a new idea for the research on the anisotropy of rock permeability.
Diyuan Li; Quanqi Zhu; Wenjian Wang. Anisotropic rock permeability evolution model based on wing crack propagation after dynamic load testing. IOP Conference Series: Earth and Environmental Science 2020, 570, 032027 .
AMA StyleDiyuan Li, Quanqi Zhu, Wenjian Wang. Anisotropic rock permeability evolution model based on wing crack propagation after dynamic load testing. IOP Conference Series: Earth and Environmental Science. 2020; 570 (3):032027.
Chicago/Turabian StyleDiyuan Li; Quanqi Zhu; Wenjian Wang. 2020. "Anisotropic rock permeability evolution model based on wing crack propagation after dynamic load testing." IOP Conference Series: Earth and Environmental Science 570, no. 3: 032027.
To study the effect of strength, stiffness and inclination angle of square inclusions on failure characteristics of rock, uniaxial compression tests were carried out on prismatic sandstone containing a square hole with different filling modes and hole angles using a servo-hydraulic loading system. Digital image correlation and acoustic emission techniques were jointly applied to analyze the damage and fracture process, and the crack stress thresholds were determined qualitatively and quantitatively by combining the stress–strain behavior. The results show that the mechanical properties and crack stress thresholds of pre-holed specimens increase with the increase of the strength and stiffness of inclusions, and are affected by the hole angle. Rock failure is mainly caused by secondary crack propagation and shear crack coalescence, eventually forming mixed tensile-shear failure. The crack behavior, especially the crack initiation position, is affected by the filling mode and the hole angle. Interface debonding tends to initiate at the vertical interface, while interface slipping tends to propagate along the inclined interface. Under identical loading conditions, the specimen with 45° hole is more susceptible to crack and damage than that with 0° hole. Notably, inclusions can inhibit the hole deformation and the fracture of rock matrix, especially the sidewall spalling of 0° hole.
Quanqi Zhu; Diyuan Li. Experimental Investigation on Crack Behavior and Stress Thresholds of Sandstone Containing a Square Inclusion under Uniaxial Compression. Applied Sciences 2020, 10, 7621 .
AMA StyleQuanqi Zhu, Diyuan Li. Experimental Investigation on Crack Behavior and Stress Thresholds of Sandstone Containing a Square Inclusion under Uniaxial Compression. Applied Sciences. 2020; 10 (21):7621.
Chicago/Turabian StyleQuanqi Zhu; Diyuan Li. 2020. "Experimental Investigation on Crack Behavior and Stress Thresholds of Sandstone Containing a Square Inclusion under Uniaxial Compression." Applied Sciences 10, no. 21: 7621.
The uniaxial compressive strength (UCS) is considered as a significant parameter related to rock material in design of geotechnical structures connected to the rock mass. Determining UCS values in laboratory is costly and time consuming, hence, its indirect determination through use of rock index tests is of a great interest and advantage. This study presents a prediction process of the UCS values through the use of three non-destructive tests i.e., p-wave velocity, Schmidt hammer and density. This process was done by developing an intelligent predictive technique namely the group method of data handling (GMDH). Before constructing intelligence system, a series of experimental equations were proposed using three non-destructive tests. The results showed that there is a need to propose new model with taking advantages of all three non-destructive tests results. Then, several GMDH models were built through the use of various parametric studies on the most effective GMDH factors. For comparison purposes, an artificial neural network (ANN) was also modelled to predict rock strength. The obtained results of the ANN and GMDH were assessed based on system error and coefficient of determination values. The results confirmed that the proposed GMDH model is an applicable, powerful, and practical intelligence system that is able to provide an acceptable accuracy level for predicting rock strength.
Diyuan Li; Danial Jahed Armaghani; Jian Zhou; Sai Hin Lai; Mahdi Hasanipanah. A GMDH Predictive Model to Predict Rock Material Strength Using Three Non-destructive Tests. Journal of Nondestructive Evaluation 2020, 39, 1 -14.
AMA StyleDiyuan Li, Danial Jahed Armaghani, Jian Zhou, Sai Hin Lai, Mahdi Hasanipanah. A GMDH Predictive Model to Predict Rock Material Strength Using Three Non-destructive Tests. Journal of Nondestructive Evaluation. 2020; 39 (4):1-14.
Chicago/Turabian StyleDiyuan Li; Danial Jahed Armaghani; Jian Zhou; Sai Hin Lai; Mahdi Hasanipanah. 2020. "A GMDH Predictive Model to Predict Rock Material Strength Using Three Non-destructive Tests." Journal of Nondestructive Evaluation 39, no. 4: 1-14.
The deep fissured rock mass is affected by coupled effects of initial ground stress and external dynamic disturbance. In order to study the effect of internal flaw on pre-stressed rock mechanical responses and failure behavior under impact loading, intact granite specimens and specimens with different flaw inclinations are tested by a modified split Hopkinson pressure bar (SHPB) and digital image correlation (DIC) method. The results show that peak strain and dynamic strength of intact specimens and specimens with different flaw angles (α) decrease with the increase of axial static pressure. The 90° flaw has weak reduction effect on peak strain, dynamic strength and combined strength, while 45° and 0° flaws have remarkable reduction effect. Specimens with 90° flaw are suffered combined shear and tensile failure under middle and low axial static pre-stresses, and suffered shear failure under high axial static pre-stresses. Specimens with 45° and 0° flaws are suffered oblique shear failure caused by pre-existing flaw under different axial static pre-stresses. Besides, based on digital image correlation method, it is found that micro-cracks before formation of macro fractures (include shear and tensile fractures) belong to tensile cracks. Tensile and shear strain localizations at pre-existing flaw tip for specimen with 45° and 0° flaws are produced much earlier than that at other positions.
Peng Xiao; Di-Yuan Li; Guo-Yan Zhao; Quan-Qi Zhu; Huan-Xin Liu; Chun-Shun Zhang. Mechanical properties and failure behavior of rock with different flaw inclinations under coupled static and dynamic loads. Journal of Central South University 2020, 27, 2945 -2958.
AMA StylePeng Xiao, Di-Yuan Li, Guo-Yan Zhao, Quan-Qi Zhu, Huan-Xin Liu, Chun-Shun Zhang. Mechanical properties and failure behavior of rock with different flaw inclinations under coupled static and dynamic loads. Journal of Central South University. 2020; 27 (10):2945-2958.
Chicago/Turabian StylePeng Xiao; Di-Yuan Li; Guo-Yan Zhao; Quan-Qi Zhu; Huan-Xin Liu; Chun-Shun Zhang. 2020. "Mechanical properties and failure behavior of rock with different flaw inclinations under coupled static and dynamic loads." Journal of Central South University 27, no. 10: 2945-2958.
Flaws and discontinuities play a crucial role in the failure process of rocks. To investigate the fracturing mechanism of rock with combined flaws composed of crack and hole, the digital image correlation (DIC) method is used to record and analyze the rock failure behavior. Coupled static and dynamic loads are applied on granite specimens with prefabricated flaws by a modified split Hopkinson pressure bar (SHPB) device. The dynamic mechanical properties of the granite specimens are affected by the flaw inclinations with the loading directions. With the inclination angle increasing, the combined strength and peak strain both decrease first and then increase. Full- and local-field strain evolution of the granite specimens is analyzed in a quantitative way by using DIC technique. The specimens with a flaw angle of 45° are broken relatively evenly with homogenous small particle sizes. The variation trend of fragment sizes is consistent with that of combined strength and absorption energy of the specimens.
Diyuan Li; Feihong Gao; Zhenyu Han; Quanqi Zhu. Full- and Local-Field Strain Evolution and Fracture Behavior of Precracked Granite under Coupled Static and Dynamic Loads. Shock and Vibration 2020, 2020, 1 -15.
AMA StyleDiyuan Li, Feihong Gao, Zhenyu Han, Quanqi Zhu. Full- and Local-Field Strain Evolution and Fracture Behavior of Precracked Granite under Coupled Static and Dynamic Loads. Shock and Vibration. 2020; 2020 ():1-15.
Chicago/Turabian StyleDiyuan Li; Feihong Gao; Zhenyu Han; Quanqi Zhu. 2020. "Full- and Local-Field Strain Evolution and Fracture Behavior of Precracked Granite under Coupled Static and Dynamic Loads." Shock and Vibration 2020, no. : 1-15.
The fracture behavior of the disc specimens in the Brazilian test is closely related to the reliability and accuracy of the experimental results. To comprehensively investigate the effect of various loading methods and rock material types on the failure mechanism of the Brazilian discs, five different rock types tested with three typical loading methods were employed in this work. The digital image correlation (DIC) method was applied to record and analyze the strain and displacement field of the specimens during the loading process. Experimental results indicate that the peak load and deformation characteristics of the Brazilian discs are strongly affected by the loading types. The Brazilian test with the Chinese standard is evidently not suitable for measuring the tensile strength of rocks, and the other two testing methods may lead to an invalid failure mode for rock materials with high stiffness and tensile to compressive strength ratio. Furthermore, it revealed that the maximum equivalent stress point of a disc specimen is co-controlled by the material stiffness and its tensile–compression ratio. The present work shows that it is necessary to select a suitable loading configuration for each rock type in the Brazilian test.
Diyuan Li; Bang Li; Zhenyu Han; Quanqi Zhu. Evaluation on Rock Tensile Failure of the Brazilian Discs under Different Loading Configurations by Digital Image Correlation. Applied Sciences 2020, 10, 5513 .
AMA StyleDiyuan Li, Bang Li, Zhenyu Han, Quanqi Zhu. Evaluation on Rock Tensile Failure of the Brazilian Discs under Different Loading Configurations by Digital Image Correlation. Applied Sciences. 2020; 10 (16):5513.
Chicago/Turabian StyleDiyuan Li; Bang Li; Zhenyu Han; Quanqi Zhu. 2020. "Evaluation on Rock Tensile Failure of the Brazilian Discs under Different Loading Configurations by Digital Image Correlation." Applied Sciences 10, no. 16: 5513.
Numerical models of a deep and inverted-U-shaped roadway were established by a particle flow code (PFC2D), and four numerical tests were performed with different blasting locations. The dynamic response characteristics of the deep roadway under blasting disturbance were thoroughly analyzed. According to the failure patterns resulting from the simulations, the dynamic stability of the arch was stronger than that of the vertical wall. The effect of the blasting location on the blasting vibration was assessed, and the diffraction start region and diffraction end region of the stress wave were obtained. The radial stress wave and tangential stress wave around the deep roadway were obtained during the blasting. The results show that the diffraction start region and diffraction end region of the stress wave were related to the fluctuation of stress wave. The effect of depth on the dynamic stability of roadways were analyzed. The results show that the damage around the borehole will be inhibited in the deeper stratum, and the vicinity of the roadway are more prone to break in the deeper stratum.
Jiadong Qiu; Diyuan Li; Xibing Li; Quanqi Zhu. Numerical investigation on the stress evolution and failure behavior for deep roadway under blasting disturbance. Soil Dynamics and Earthquake Engineering 2020, 137, 106278 .
AMA StyleJiadong Qiu, Diyuan Li, Xibing Li, Quanqi Zhu. Numerical investigation on the stress evolution and failure behavior for deep roadway under blasting disturbance. Soil Dynamics and Earthquake Engineering. 2020; 137 ():106278.
Chicago/Turabian StyleJiadong Qiu; Diyuan Li; Xibing Li; Quanqi Zhu. 2020. "Numerical investigation on the stress evolution and failure behavior for deep roadway under blasting disturbance." Soil Dynamics and Earthquake Engineering 137, no. : 106278.
Stability and safety of rock structures are easily influenced by the dynamic disturbance, especially when weak joint planes exist. In order to investigate the filling joint effect on the dynamic response of rock specimens, a series of impact dynamic tests were conducted by a modified split Hopkinson pressure bar (SHPB) system. A sandwich type of sandstone specimens filling with different thicknesses layer of cemented mortar (filling joint) were tested in the study. The results show that the transmission coefficient, dynamic strength and energy absorption all decrease with increasing joint thickness. However, the reflection coefficient, peak strain and joint closure show an opposite variation trend. In addition, the deformation of the cemented mortar joint is the main reason to cause the deformation and final failure of jointed rock specimens. Tensile cracks dominate the fracturing behavior during the dynamic loading, but they have a slight influence on the final failure mode which transforms from localized slabbing to axial splitting failure with the filling joint becoming thicker.
Zhenyu Han; Diyuan Li; Tao Zhou; Quanqi Zhu; P.G. Ranjith. Experimental study of stress wave propagation and energy characteristics across rock specimens containing cemented mortar joint with various thicknesses. International Journal of Rock Mechanics and Mining Sciences 2020, 131, 104352 .
AMA StyleZhenyu Han, Diyuan Li, Tao Zhou, Quanqi Zhu, P.G. Ranjith. Experimental study of stress wave propagation and energy characteristics across rock specimens containing cemented mortar joint with various thicknesses. International Journal of Rock Mechanics and Mining Sciences. 2020; 131 ():104352.
Chicago/Turabian StyleZhenyu Han; Diyuan Li; Tao Zhou; Quanqi Zhu; P.G. Ranjith. 2020. "Experimental study of stress wave propagation and energy characteristics across rock specimens containing cemented mortar joint with various thicknesses." International Journal of Rock Mechanics and Mining Sciences 131, no. : 104352.
Iron is one of the most applicable metals in the world. The global price of iron ore is determined based on demand and supply. There are numerous parameters (e.g., price of steel, steel production, oil price, gold price, interest rate, inflation rate, iron production, and aluminum price) affecting the global iron ore price. Considering the high number of effective parameters and existence of complex relationship among them, artificial intelligence-based approaches can be employed to predict iron ore price. In this paper, a new intelligence system namely group method of data handling (GMDH) was developed and introduced to predict the price of iron ore. For comparison purposes, four other techniques i.e., autoregressive integrated moving average (ARIMA), support vector regression (SVR), artificial neural network (ANN), and classification and regression tree (CART) were developed for prediction of monthly iron ore price. Then, using testing datasets, the developed models were validated and their performance capacities were compared. The results showed that performance prediction of the GMDH model is significantly better than other predictive models based on four performance indices i.e., root mean square error, variance account for (VAF), mean absolute error, and mean absolute percentage error. Results of VAF (97.89%, 90.81%, 80.95%, 55.02%, and 23.87% for GMDH, SVR, ANN, CART, and ARIMA models, respectively) revealed that the GMDH technique is able to predict iron ore price with higher degree of accuracy compared to the other techniques.
Diyuan Li; Mohammad Reza Moghaddam; Masoud Monjezi; Danial Jahed Armaghani; Amirhossein Mehrdanesh. Development of a Group Method of Data Handling Technique to Forecast Iron Ore Price. Applied Sciences 2020, 10, 2364 .
AMA StyleDiyuan Li, Mohammad Reza Moghaddam, Masoud Monjezi, Danial Jahed Armaghani, Amirhossein Mehrdanesh. Development of a Group Method of Data Handling Technique to Forecast Iron Ore Price. Applied Sciences. 2020; 10 (7):2364.
Chicago/Turabian StyleDiyuan Li; Mohammad Reza Moghaddam; Masoud Monjezi; Danial Jahed Armaghani; Amirhossein Mehrdanesh. 2020. "Development of a Group Method of Data Handling Technique to Forecast Iron Ore Price." Applied Sciences 10, no. 7: 2364.
Flaws in different geometries are widely existed in rock masses and play a significant role in the stability of rock engineering structures. To investigate the failure mechanisms of rock block with combined flaws under coupled static and dynamic loads, a series of experiments were conducted on granite containing pre-existing fissures in the vicinity of a circular opening by using a modified split Hopkinson pressure bar (SHPB) device. Digital image correlation (DIC) method was applied to record the real-time cracking processes. The results show that the fissure inclination angle and the number of fissure are important factors affecting the mechanical properties and cracking processes. The strength of specimens shows a decrease trend with fissure inclination angle increasing, and the localized strain of fissure tip can be used to identify and reveal the crack initiation in the experiments. Based on the temporal and spatial evolution rules of principal strain field obtained by DIC technique, the crack sequences and crack paths of typical specimens are summarized in the paper, especially the crack initiation position. The roof, floor of the opening and the fissure tip are the critical zones where the new cracks usually initiate from. The crack types of the specimens can be categorized as wing crack, coplanar secondary crack, oblique secondary crack, tensile crack and shear crack based on the observation of the failure processes.
Diyuan Li; Feihong Gao; Zhenyu Han; Quanqi Zhu. Experimental evaluation on rock failure mechanism with combined flaws in a connected geometry under coupled static-dynamic loads. Soil Dynamics and Earthquake Engineering 2020, 132, 106088 .
AMA StyleDiyuan Li, Feihong Gao, Zhenyu Han, Quanqi Zhu. Experimental evaluation on rock failure mechanism with combined flaws in a connected geometry under coupled static-dynamic loads. Soil Dynamics and Earthquake Engineering. 2020; 132 ():106088.
Chicago/Turabian StyleDiyuan Li; Feihong Gao; Zhenyu Han; Quanqi Zhu. 2020. "Experimental evaluation on rock failure mechanism with combined flaws in a connected geometry under coupled static-dynamic loads." Soil Dynamics and Earthquake Engineering 132, no. : 106088.
The excavation stability of tunnel is a key problem in tunneling engineering. A mechanical model is developed to determine the boundary curve of the plastic zone and the principal stress distribution of the surrounding rock of a circular tunnel under non-tectonic stress. Specifically, the effects of different influence factors on the shape of the plastic zone and the principal stress of the surrounding rock are quantitatively analyzed. Subsequently, the Mohr-Coulomb failure criterion is utilized to determine the yield failure of the surrounding rock mass. Furthermore, technical approaches and control measures for supporting the surrounding rock are put forward. In particular, the “long and short” coordinated hierarchical support technology with “anchor cables (or long bolts) + bolts” as the main support strategy has been recommended. Finally, the proposed support technology is validated for several typical tunnels by the numerical simulation method. The results indicate that the stability of the surrounding rock of a circular tunnel can be improved by restraining the malignant extension of the plastic zone, improving the principal stress environment, and allowing uniform distribution of the plastic zone within the controllable range of the support system. These results are helpful for optimization of support technology to stabilize the surrounding rock of a circular tunnel under non-tectonic stresses.
Shaohua Du; Diyuan Li; Bo Ruan; Genshui Wu; Bao Pan; Jinyin Ma. Deformation and fracture of circular tunnels under non-tectonic stresses and its support control. European Journal of Environmental and Civil Engineering 2020, 1 -24.
AMA StyleShaohua Du, Diyuan Li, Bo Ruan, Genshui Wu, Bao Pan, Jinyin Ma. Deformation and fracture of circular tunnels under non-tectonic stresses and its support control. European Journal of Environmental and Civil Engineering. 2020; ():1-24.
Chicago/Turabian StyleShaohua Du; Diyuan Li; Bo Ruan; Genshui Wu; Bao Pan; Jinyin Ma. 2020. "Deformation and fracture of circular tunnels under non-tectonic stresses and its support control." European Journal of Environmental and Civil Engineering , no. : 1-24.
The stability of coal mine roadways in jointed soft rock masses is an important issue for safe and efficient mining production in underground mines. Taking a main haulageway of a coal mine in Guizhou Province in China as the research background, the instability failure caused by large deformation of a roadway in a cracked rock mass was analysed, and its support control measures were put forward. First, the stability of the surrounding rock was evaluated by field investigation on the failure characteristics and statistics for the development of joints and fissures in the surrounding rock. Second, the corresponding numerical model was established by using FLAC3D software, and the influence of the lateral pressure coefficient λ on the plastic zone and principal stress were analysed quantitatively. In addition, the evolution process of the plastic zone over time was summarized. Furthermore, the key points of the reinforcement plan and support parameter design were provided on the basis of the technical approach for deformation control of the surrounding rock of the roadway. The original supporting scheme was optimized step by step, and the combined supporting scheme with “short bolt, long anchor cable and two-step grouting shell” serving as the main concept was put forward. Finally, the results of numerical calculation and field practice showed that the optimized scheme could effectively restrain the local deformation in the plastic zone of the surrounding rock of the roadway. The overall deformation was in a controllable range. In addition, the reinforced anchor cable was anchored to the deep part of the surrounding rock, ensuring the safety and stability of the roadway.
Shaohua Du; Diyuan Li; Weijian Yu; Jian Zhang; Fangfang Liu. Stability Analysis and Support Control for a Jointed Soft Rock Roadway Considering Different Lateral Stresses. Geotechnical and Geological Engineering 2019, 38, 237 -253.
AMA StyleShaohua Du, Diyuan Li, Weijian Yu, Jian Zhang, Fangfang Liu. Stability Analysis and Support Control for a Jointed Soft Rock Roadway Considering Different Lateral Stresses. Geotechnical and Geological Engineering. 2019; 38 (1):237-253.
Chicago/Turabian StyleShaohua Du; Diyuan Li; Weijian Yu; Jian Zhang; Fangfang Liu. 2019. "Stability Analysis and Support Control for a Jointed Soft Rock Roadway Considering Different Lateral Stresses." Geotechnical and Geological Engineering 38, no. 1: 237-253.