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Prof. Dr. shaofeng wang
School of Resources and Safety Engineering, Central South University, Changsha 410083, China

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0 Mining
0 Mining Engineering
0 Rock Mechanics
0 Slope Stability

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Journal article
Published: 22 August 2021 in Materials
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Hard-core sandwich plates are widely used in the field of aviation, aerospace, transportation, and construction thanks to their superior mechanical properties such as sound absorption, heat insulation, shock absorption, and so on. As an important form, the circular sandwich is very common in the field of engineering. Thus, theoretical analysis and numerical simulation of bending and buckling for isotropic circular sandwich plates with a hard core (SP-HC) are conducted in this study. Firstly, the revised Reissner’s theory was used to derive the bending equations of isotropic circular SP-HC for the first time. Then, the analytic solutions to bending deformation for circular and annular sandwich SP-HCs under some loads and boundary conditions were obtained through the decoupled simplification. Secondly, an analytic solution to bending deformation for a simply supported annular SP-HC under uniformly distributed bending moment and shear force along the inner edge was given. Finally, the differential equations of buckling for circular SP-HCs in polar coordinates were derived to obtain the critical loads of overall instability of SP-HC under simply supported and fixed-end supported boundary conditions. Meanwhile, the numerical simulations using Nastran software were conducted to compare with the theoretical analyses using Reissner’s theory and the derived models in this study. The theoretical and numerical results showed that the present formula proposed in this study can be suitable to both SP-HC and SP-SC. The efforts can provide valuable information for safe and stable application of multi-functional composite material of SP-HC.

ACS Style

Zizi Pi; Zilong Zhou; ZongBai Deng; Shaofeng Wang. Bending and Buckling of Circular Sandwich Plates with a Hardened Core. Materials 2021, 14, 4741 .

AMA Style

Zizi Pi, Zilong Zhou, ZongBai Deng, Shaofeng Wang. Bending and Buckling of Circular Sandwich Plates with a Hardened Core. Materials. 2021; 14 (16):4741.

Chicago/Turabian Style

Zizi Pi; Zilong Zhou; ZongBai Deng; Shaofeng Wang. 2021. "Bending and Buckling of Circular Sandwich Plates with a Hardened Core." Materials 14, no. 16: 4741.

Journal article
Published: 01 July 2021 in Transactions of Nonferrous Metals Society of China
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Rocks are likely to undergo spalling failure under dynamic loading. The fracture development and rock failure behaviours were investigated during dynamic tensile loading. Tests were conducted with a split-Hopkinson pressure bar (SHPB) in four different impact loading conditions. Thin sections near failure surfaces were also made to evaluate the growth patterns of fractures observed by polarizing microscope. Scanning electron microscopy (SEM) was used to observe mineral grains on failure surfaces and to evaluate their response to loading and failure. The results indicate that the number of spalling cracks increases with increase in peak impact loads and that quartz sustains abundant intergranular fracturing. Cleavage planes and their direction relative to loading play a vital role in rock strength and fracturing. Separation along cleavage planes perpendicular to loading without the movement of micaceous minerals parallel to loading appears to be unique to the rock spalling process.

ACS Style

Lin-Qi Huang; Jun Wang; Aliakbar Momeni; Shao-Feng Wang. Spalling fracture mechanism of granite subjected to dynamic tensile loading. Transactions of Nonferrous Metals Society of China 2021, 31, 2116 -2127.

AMA Style

Lin-Qi Huang, Jun Wang, Aliakbar Momeni, Shao-Feng Wang. Spalling fracture mechanism of granite subjected to dynamic tensile loading. Transactions of Nonferrous Metals Society of China. 2021; 31 (7):2116-2127.

Chicago/Turabian Style

Lin-Qi Huang; Jun Wang; Aliakbar Momeni; Shao-Feng Wang. 2021. "Spalling fracture mechanism of granite subjected to dynamic tensile loading." Transactions of Nonferrous Metals Society of China 31, no. 7: 2116-2127.

Journal article
Published: 29 June 2021 in Measurement
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The surrounding rocks of underground engineering are usually subjected to the coupling of compressive and shear stresses. The variable angle shear tests (VASTs) and direct shear tests (DSTs) are two types of lab tests that can easily achieve different compression-shear stress states. The VASTs and DSTs on cubic rock specimens were conducted to analyze the shear strength parameters and acoustic emission (AE) characteristics during rock failure process. The test results show that it is more reasonable to use the test data in VASTs with shear angles greater than 45° for calculating the shear strength parameters of rocks. The essence of changing the shear angles in VASTs or the normal loads in DSTs is to change the micro-crack component produced in the compression-shear failure mode, in which the shear cracking mainly trigger the AE signals with low peak frequency around 100 kHz, and the tensile cracking mainly induce the AE signals with relatively high peak frequency around 300 kHz. Although the main type of micro-crack produced by shear failure and compression failure are both shear micro-crack, the micro-cracks generated by shear failure have higher efficiency in generating AE energy compared with compression failure, which means that the large-scale micro-crack expansion activities are more intense in shear failure than that in compression failure.

ACS Style

Kun Du; Xuefeng Li; Shanyong Wang; Ming Tao; Gen Li; Shaofeng Wang. Compression-shear Failure Properties and Acoustic Emission (AE) Characteristics of Rocks in Variable Angle Shear and Direct Shear Tests. Measurement 2021, 183, 109814 .

AMA Style

Kun Du, Xuefeng Li, Shanyong Wang, Ming Tao, Gen Li, Shaofeng Wang. Compression-shear Failure Properties and Acoustic Emission (AE) Characteristics of Rocks in Variable Angle Shear and Direct Shear Tests. Measurement. 2021; 183 ():109814.

Chicago/Turabian Style

Kun Du; Xuefeng Li; Shanyong Wang; Ming Tao; Gen Li; Shaofeng Wang. 2021. "Compression-shear Failure Properties and Acoustic Emission (AE) Characteristics of Rocks in Variable Angle Shear and Direct Shear Tests." Measurement 183, no. : 109814.

Journal article
Published: 09 April 2021 in Mathematics
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Natural soil and rock materials and the associated artificial materials have cracks, fractures, or contacts and possibly produce rock fragments or particles during geological, environmental, and stress conditions. Based on color gradient distribution, a digital image processing method was proposed to automatically recognize the outlines of fractures, fragments, and particles. Then, the fracture network, block size distribution, and particle size distribution were quantitatively characterized by calculating the fractal dimension and equivalent diameter distribution curve. The proposed approach includes the following steps: production of an image matrix; calculation of the gradient magnitude matrix; recognition of the outlines of fractures, fragments, or particles; and characterization of the distribution of fractures, fragments, or particles. Case studies show that the fractal dimensions of cracks in the dry mud layer, ceramic panel, and natural rock mass are 1.4332, 1.3642, and 1.5991, respectively. The equivalent diameters of fragments of red sandstone, granite, and marble produced in quasi-static compression failures are mainly distributed in the ranges of 20–40 mm, 25–65 mm, and 10–35 mm, respectively. The fractal dimension of contacts between mineral particles and the distribution of the equivalent diameters of particles in rock are 1.6381 and 0.8–3.6 mm, respectively. The proposed approach provides a computerized method to characterize quantitatively and automatically the structure characteristics of soil/rock or soil/rock-like materials. By this approach, the remote sensing for characterization can be achieved.

ACS Style

Zizi Pi; Zilong Zhou; Xibing Li; Shaofeng Wang. Digital Image Processing Method for Characterization of Fractures, Fragments, and Particles of Soil/Rock-Like Materials. Mathematics 2021, 9, 815 .

AMA Style

Zizi Pi, Zilong Zhou, Xibing Li, Shaofeng Wang. Digital Image Processing Method for Characterization of Fractures, Fragments, and Particles of Soil/Rock-Like Materials. Mathematics. 2021; 9 (8):815.

Chicago/Turabian Style

Zizi Pi; Zilong Zhou; Xibing Li; Shaofeng Wang. 2021. "Digital Image Processing Method for Characterization of Fractures, Fragments, and Particles of Soil/Rock-Like Materials." Mathematics 9, no. 8: 815.

Journal article
Published: 16 March 2021 in Applied Sciences
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Rockbursts represent hazardous dynamic disasters for underground coal mines and other underground rock engineering projects. Some bursting liability indices are put forward and applied to identify the likelihood of rock burst occurrence. The classification criteria of the bursting liability indices are proved to be reasonable for coals, but they are still immature for non-coal rocks. Thus, it is uncertain that it is reasonable to use the classification criteria of coal for evaluating the bursting liability of non-coal rocks. Hence, in this study, a large amount of data, such as the basic mechanical parameters, i.e., Poisson’s ratio μ, elastic modulus E, uniaxial compressive strength σc , and uniaxial tensile strength σt , and the bursting liability indices, i.e., elastic strain energy index WET , bursting energy index Wcf , dynamic fracture duration time DT, and brittleness index B, of different coals and non-coal rocks were collected in China. Then, the differences of mechanical parameters and rockburst tendency indices between coal and non-coal rocks were studied systematically, and apart from the Poisson’s ratio μ, the other three basic mechanical parameters of coal and non-coal rocks have great differences in data distribution and concentration scope, which proved that the non-coal rocks cannot share the same index system and classification criteria of coals. In addition, the evaluation results of a single index for rock bursting liability of rocks were directly compared in pairs, and the inconsistency rate for coals is about 42–68%. It is necessary to build a comprehensive evaluation method to evaluate the bursting liability of rocks. At last, the modified rockburst tendency classification criteria for non-coal rocks were put forward. It is reasonable to use the classification criteria of the WET and Wcf to classify the bursting liability of non-coal rocks, while it is unreasonable to use that of the DT and σc . It has been concluded that the index B are more suitable for non-coal rocks, and a new index, named strength decrease rate (SDR), was proposed to determine the bursting liability, which is the ratio of uniaxial compressive strength σc to duration of dynamic fracture DT.

ACS Style

Kun Du; Yu Sun; Songge Yang; Shizhan Lv; Shaofeng Wang. Differences of Mechanical Parameters and Rockburst Tendency Indices between Coal and Non-Coal Rocks and Modified Rockburst Tendency Classification Criteria for Non-Coal Rocks. Applied Sciences 2021, 11, 2641 .

AMA Style

Kun Du, Yu Sun, Songge Yang, Shizhan Lv, Shaofeng Wang. Differences of Mechanical Parameters and Rockburst Tendency Indices between Coal and Non-Coal Rocks and Modified Rockburst Tendency Classification Criteria for Non-Coal Rocks. Applied Sciences. 2021; 11 (6):2641.

Chicago/Turabian Style

Kun Du; Yu Sun; Songge Yang; Shizhan Lv; Shaofeng Wang. 2021. "Differences of Mechanical Parameters and Rockburst Tendency Indices between Coal and Non-Coal Rocks and Modified Rockburst Tendency Classification Criteria for Non-Coal Rocks." Applied Sciences 11, no. 6: 2641.

Journal article
Published: 01 February 2021 in International Journal of Geomechanics
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Stress conditions and preflaws are prominent conditions influencing the cuttability of deep hard rock. This study aims to investigate the cuttability of intact, prefractured, and drilled rocks under biaxial confining stress, uniaxial confining stress, and stress-free conditions using a conical cutter in rock fragmentation tests on true triaxial loading apparatus. Peak cutter force and penetration depth at rock initial fracture and final failure of the rock specimen were used to reflect rock cuttability. The results show that the rock cuttability increases with stress in one direction decreasing under biaxial confining stresses, and presents a decreasing trend followed by an initial increase as uniaxial confining stress increases. The prefractures and boreholes in rock can further improve the rock cuttability, compared with intact rock. A series of cuttability improvement measures were proposed to provide a suitable condition for the application of nonexplosive mechanized mining in hard rock. Finally, comparative field tests were performed on a single-face entryway and a peninsula-shaped pillar, in which the mean value of cutting efficiency increased from 32.6 to 107.7 t/h, and the dust production and cutter wearout failure reduced significantly.

ACS Style

Shaofeng Wang; Licheng Sun; Xibing Li; Shanyong Wang; Kun Du; Xiang Li; Fan Feng. Experimental Investigation of Cuttability Improvement for Hard Rock Fragmentation Using Conical Cutter. International Journal of Geomechanics 2021, 21, 06020039 .

AMA Style

Shaofeng Wang, Licheng Sun, Xibing Li, Shanyong Wang, Kun Du, Xiang Li, Fan Feng. Experimental Investigation of Cuttability Improvement for Hard Rock Fragmentation Using Conical Cutter. International Journal of Geomechanics. 2021; 21 (2):06020039.

Chicago/Turabian Style

Shaofeng Wang; Licheng Sun; Xibing Li; Shanyong Wang; Kun Du; Xiang Li; Fan Feng. 2021. "Experimental Investigation of Cuttability Improvement for Hard Rock Fragmentation Using Conical Cutter." International Journal of Geomechanics 21, no. 2: 06020039.

Journal article
Published: 14 January 2021 in Applied Sciences
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The surrounding rocks of underground engineering are generally subjected to a biaxial compressive stress condition. The failure properties of rocks under such a stress condition are worthy of being studied to ensure the stability of surrounding rock. This study aims to investigate the mechanical characteristics and acoustic emission (AE) properties of granite, marble, and sandstone in biaxial compression tests. Under biaxial confinements, it is evident that the elastic moduli of the three types of rocks decrease, and the plasticity increases monotonously with the increase of the intermediate principal stress σ2. As σ2 increases, the biaxial compressive strength σbcs of rock increases initially and subsequently decreases. The lateral strain ε2 of rock under biaxial confinement is controlled by both σ1 and σ2, and the restrain degree in the development of microcracks and the constrain extent in the expansion along the direction of σ2 are both enhanced gradually with increase in σ2. The sharp increase points of AE hit and AE count indicate that the failure will occur soon. The AF-RA distribution of AE signals shows that the increase of σ2 causes more tensile cracks in rock. According to the dip failure angle of macro-cracks in rock under biaxial confinement, the failure modes of granite and marble are slabbing, while failure mode of sandstone is shear. In addition, the σ2 has a positive effect on the mass ratio of large size fragments after rock failure. An exponent relationship between the σbcs and σ2 was found, and the inner apices–inscribed Drucker–Prager criterion can be used to predict the σbcs of rock.

ACS Style

Kun Du; Minghui Liu; Chengzhi Yang; Ming Tao; Fukang Feng; Shaofeng Wang. Mechanical and Acoustic Emission (AE) Characteristics of Rocks under Biaxial Confinements. Applied Sciences 2021, 11, 769 .

AMA Style

Kun Du, Minghui Liu, Chengzhi Yang, Ming Tao, Fukang Feng, Shaofeng Wang. Mechanical and Acoustic Emission (AE) Characteristics of Rocks under Biaxial Confinements. Applied Sciences. 2021; 11 (2):769.

Chicago/Turabian Style

Kun Du; Minghui Liu; Chengzhi Yang; Ming Tao; Fukang Feng; Shaofeng Wang. 2021. "Mechanical and Acoustic Emission (AE) Characteristics of Rocks under Biaxial Confinements." Applied Sciences 11, no. 2: 769.

Journal article
Published: 01 September 2020 in International Journal of Geomechanics
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ACS Style

Zhenghong Chen; Linqi Huang; Xibing Li; Lei Weng; Shaofeng Wang. Influences of the Height to Diameter Ratio on the Failure Characteristics of Marble under Unloading Conditions. International Journal of Geomechanics 2020, 20, 04020148 .

AMA Style

Zhenghong Chen, Linqi Huang, Xibing Li, Lei Weng, Shaofeng Wang. Influences of the Height to Diameter Ratio on the Failure Characteristics of Marble under Unloading Conditions. International Journal of Geomechanics. 2020; 20 (9):04020148.

Chicago/Turabian Style

Zhenghong Chen; Linqi Huang; Xibing Li; Lei Weng; Shaofeng Wang. 2020. "Influences of the Height to Diameter Ratio on the Failure Characteristics of Marble under Unloading Conditions." International Journal of Geomechanics 20, no. 9: 04020148.

Journal article
Published: 02 August 2020 in International Journal of Rock Mechanics and Mining Sciences
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A series of rock tests including Brazilian indirect tension test (BITT), three-point bending test (TPBT), modified shear test (MST) and uniaxial compression test (UCT) were conducted to investigate the acoustic emission (AE) characteristics and crack classification during rock fracture. The test results show that the rock fracture process presents an obvious segmented variation feature and has a dramatic increasing period, according to the change trends of AE hits and AE energy characteristic parameters. The AE characteristics are closely related to the types of micro-cracks produced in the rock fracture process. The elastic strain energy released by shear crack is greater than that released by tensile crack. Most of AE signals generated in compression and shear failures that mainly produce shear cracks have low average frequency (AF) values and low peak frequencies (below 100 kHz). On the contrary, most of AE signals generated in bending and tensile failures that mainly produce tensile cracks have low RA (ratio of rise time to amplitude) and high peak frequencies (above 100 kHz). In addition, the dividing lines were defined to distinguish the tensile cracks and shear cracks in the AF-RA scatter plots for different rocks. For instance, the AE signals above dividing line accounted for more than 62%, which indicated that the tensile cracks were dominant in TPBT. However, the AE signals below dividing line accounted for more than 74%, and the shear cracks were dominant in UCT. Therefore, the AE characteristics can be used to determine the fracture modes of rock, then to shed light on the micro-crack properties.

ACS Style

Kun Du; Xuefeng Li; Ming Tao; Shaofeng Wang. Experimental study on acoustic emission (AE) characteristics and crack classification during rock fracture in several basic lab tests. International Journal of Rock Mechanics and Mining Sciences 2020, 133, 104411 .

AMA Style

Kun Du, Xuefeng Li, Ming Tao, Shaofeng Wang. Experimental study on acoustic emission (AE) characteristics and crack classification during rock fracture in several basic lab tests. International Journal of Rock Mechanics and Mining Sciences. 2020; 133 ():104411.

Chicago/Turabian Style

Kun Du; Xuefeng Li; Ming Tao; Shaofeng Wang. 2020. "Experimental study on acoustic emission (AE) characteristics and crack classification during rock fracture in several basic lab tests." International Journal of Rock Mechanics and Mining Sciences 133, no. : 104411.

Journal article
Published: 13 April 2020 in International Journal of Rock Mechanics and Mining Sciences
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Cubic specimens of granite, marble, and sandstone, with side lengths of 50 mm, were prepared in the laboratory. True triaxial compression tests were conducted on each rock type with minor principal stress (σ3) magnitudes of 10, 20, 30, 50, and 100 MPa and the intermediate principal stress (σ2) varying from σ2 = σ3 to σ2 = σ1 (where σ1 represents the major principal stress). The experimental results demonstrated that the failure strength, fracture dip angle, non-linear behavior and failure mode of these rocks under true triaxial conditions were affected by both σ2 and σ3, as well as by the rock lithology. When σ3 was kept constant and σ2 increased, failure strength showed an initial increase followed by a decrease, whereas the fracture dip angle increased monotonically. The non-linear behavior before the peak strength point of granite became more apparent by the increase of σ3, whereas σ2 had an opposite effect on the non-linear behavior of granite under high σ3 (e.g. 100 MPa). The non-linear behavior before the peak strength point was always found in marble and sandstone for all of the stress state conditions. Analyses of fracture dip angle and failure mode showed that when σ3 = 10, 20, and 30 MPa and σ2/σ3 ≥ 5, 7.5, and 10, respectively, the failure mode of granite changed from shear to slabbing, whereas marble and sandstone always fractured in the shear direction. This study confirms that rocks may experience slabbing failure under true triaxial stress, and slabbing failure mode is likely to be induced in high-strength and brittle rocks under low σ3 with the stress ratio of σ2/σ3 exceeding a particular threshold value.

ACS Style

Kun Du; Chengzhi Yang; Rui Su; Ming Tao; Shaofeng Wang. Failure properties of cubic granite, marble, and sandstone specimens under true triaxial stress. International Journal of Rock Mechanics and Mining Sciences 2020, 130, 104309 .

AMA Style

Kun Du, Chengzhi Yang, Rui Su, Ming Tao, Shaofeng Wang. Failure properties of cubic granite, marble, and sandstone specimens under true triaxial stress. International Journal of Rock Mechanics and Mining Sciences. 2020; 130 ():104309.

Chicago/Turabian Style

Kun Du; Chengzhi Yang; Rui Su; Ming Tao; Shaofeng Wang. 2020. "Failure properties of cubic granite, marble, and sandstone specimens under true triaxial stress." International Journal of Rock Mechanics and Mining Sciences 130, no. : 104309.

Journal article
Published: 01 February 2020 in International Journal of Geomechanics
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Cubic specimens of three rocks—granite, marble, and sandstone, representing very strong rock, moderately strong rock, and weak rock, respectively—were tested under polyaxial stress. The objective was to determine the optimal strength criteria for these rocks by using the polyaxial test data. Experimental results indicated that the failure strength considerably depended on σ2 and σ3 for all the rocks. Seven well-known rock-strength criteria were employed to examine the true-triaxial data with regard to the predictability in practical applications, comparison between the best-fitting functions (experimental data) and theoretical (predicted) solutions, stress trajectories on the deviatoric plane, and stress trajectories on the meridian plane and τoct−σoct space. A detailed analysis and comparison of these criteria showed that the Mogi–Coulomb criterion, modified Wiebols–Cook criterion, and modified Lade criterion provided a better prediction of the polyaxial strength for the three rocks in most cases, which is attributed to the high σ2 dependence and sensitivity of the selected rocks. The Mogi 1971 and 1967 criteria could not be correlated to the strength parameters (cohesion and frictional angle) and failed to predict the real strength values of an in situ rock mass without complex polyaxial compression tests. Furthermore, the stress trajectories on the deviatoric plane illustrated their disadvantages in theoretical interpretation and numerical implementation. The inferiority of the Mohr–Coulomb criterion and Drucker–Prager (DP) criterion in describing the rock strength under polyaxial stress was verified by the higher deviation between the theoretical (predicted) strength values and experimental strength values. The nonconformity between the stress trajectories and experimental data for the Mohr–Coulomb criterion and DP criterion on the meridian plane and in the τoct−σoct space validates the preceding viewpoint.

ACS Style

Fan Feng; Xibing Li; Kun Du; Diyuan Li; Jamal Rostami; Shaofeng Wang. Comprehensive Evaluation of Strength Criteria for Granite, Marble, and Sandstone Based on Polyaxial Experimental Tests. International Journal of Geomechanics 2020, 20, 04019155 .

AMA Style

Fan Feng, Xibing Li, Kun Du, Diyuan Li, Jamal Rostami, Shaofeng Wang. Comprehensive Evaluation of Strength Criteria for Granite, Marble, and Sandstone Based on Polyaxial Experimental Tests. International Journal of Geomechanics. 2020; 20 (2):04019155.

Chicago/Turabian Style

Fan Feng; Xibing Li; Kun Du; Diyuan Li; Jamal Rostami; Shaofeng Wang. 2020. "Comprehensive Evaluation of Strength Criteria for Granite, Marble, and Sandstone Based on Polyaxial Experimental Tests." International Journal of Geomechanics 20, no. 2: 04019155.

Original paper
Published: 11 October 2019 in Arabian Journal of Geosciences
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Water inrush accidents are devastating to underground mining operations and cause damage. In particular, in undersea mining, mining safety is endangered as the mining-induced fractured zone extends upwards towards the vast amount of seawater. This paper describes a case study of the development of a fractured zone induced by undersea mining of a tilted ore body in the Xinli district of the Sanshandao Gold Mine in Shandong Province, China. A theoretical prediction model based on overburden movement during mining is proposed to analyse the developed height of the fractured zone induced by undersea mining of the tilted ore body. The Universal Discrete Element Code (UDEC) software program is adopted to establish a numerical model to investigate the movement and fracturing of the overlying strata during mining of the gold deposit from the – 280-m level to the – 200-m level in the Xinli district. For the study area in the – 200-m level, in which the gold deposit is currently being mined and is the closest to the seafloor, the theoretical (32.7 m) and numerical (36.23 m) results for the height of the fractured zone are in agreement with the field observations (32.1 m) from a panoramic borehole televiewer. These results indicate that the fractured zone in the Xinli mining area has not reached the seafloor and that the mine remains safe.

ACS Style

Ying Chen; Guoyan Zhao; Shaofeng Wang; Xiang Li. Investigations of the height of fractured zones in overburden induced by undersea mining. Arabian Journal of Geosciences 2019, 12, 618 .

AMA Style

Ying Chen, Guoyan Zhao, Shaofeng Wang, Xiang Li. Investigations of the height of fractured zones in overburden induced by undersea mining. Arabian Journal of Geosciences. 2019; 12 (19):618.

Chicago/Turabian Style

Ying Chen; Guoyan Zhao; Shaofeng Wang; Xiang Li. 2019. "Investigations of the height of fractured zones in overburden induced by undersea mining." Arabian Journal of Geosciences 12, no. 19: 618.

Journal article
Published: 23 August 2019 in International Journal of Rock Mechanics and Mining Sciences
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Stress conditions around deep underground mine openings can significantly influence rock fragmentation and stability, and thus the cuttability of the targeted rock. In this study, rock breakage experiments and associated regression analyses indicate nonlinear rock cuttabilities (decreasing followed by increasing) with increases in the differences between biaxial confining stresses and the values of uniaxial confining stresses. Rock breakages were found to be efficient and safe under low and no-stress conditions that require low indentation force and depth, cutting work and specific energy to completely split the rock wtih no rockburst risk. Stress concentration initially impeded rock breakage, although high uniaxial stress improved rock cuttability. Inducing high stress to fracture the rock and produce an excavation damage zone (EDZ) via stress release effectively transformed the stress condition into low confining stress or even the stress-free condition, improving rock cuttability significantly and preventing rockburst. Mining of rock in the EDZ around the pillar could be efficient, cost-effective and safe when using roadheaders, which showed high cutting efficiencies, low pick wear failures, high machine stabilities and no rockbursts. In addition, a binary linear regression model was proposed to determine the thickness variation of the EDZ correlated with the excavation span and a coupled index of rock properties and buried depth of opening. The results indicated that the thickness of the EDZ increases with increases in the buried depth of the opening, which can improve the applicability of non-explosive mechanized mining in deep mines.

ACS Style

Shaofeng Wang; Xibing Li; Jinrui Yao; Fengqiang Gong; Xiang Li; Kun Du; Ming Tao; Linqi Huang; Shaolun Du. Experimental investigation of rock breakage by a conical pick and its application to non-explosive mechanized mining in deep hard rock. International Journal of Rock Mechanics and Mining Sciences 2019, 122, 104063 .

AMA Style

Shaofeng Wang, Xibing Li, Jinrui Yao, Fengqiang Gong, Xiang Li, Kun Du, Ming Tao, Linqi Huang, Shaolun Du. Experimental investigation of rock breakage by a conical pick and its application to non-explosive mechanized mining in deep hard rock. International Journal of Rock Mechanics and Mining Sciences. 2019; 122 ():104063.

Chicago/Turabian Style

Shaofeng Wang; Xibing Li; Jinrui Yao; Fengqiang Gong; Xiang Li; Kun Du; Ming Tao; Linqi Huang; Shaolun Du. 2019. "Experimental investigation of rock breakage by a conical pick and its application to non-explosive mechanized mining in deep hard rock." International Journal of Rock Mechanics and Mining Sciences 122, no. : 104063.

Research article
Published: 13 February 2019 in Geofluids
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Excavation unloading is a primary stress condition for engineering rock mass in deep underground. Based on the unloading stress condition during the excavation operation, this paper employed a distinct element method (DEM) to simulate the unloading responses of intact and preflawed rock specimens. The simulation results revealed that the unloading failure strength, unloading damage thresholds, and cracking characteristics were largely dependent on the inclination angle α of the preflaws. With the increase in the flaw inclination angle, the unloading failure strength of a preflawed specimen exhibited a sigmoidal curve increasing trend, and it decreased by 5.5%-20% compared to the unloading failure strength of an intact specimen. Based on the crack accumulation in specimens, three damage thresholds were identified under unloading condition and two damage thresholds σci and σdi were found to be increased with the increase in the flaw inclination angle. Furthermore, when the flaw inclination angle was smaller, cracks were initiated around the preflaws, and there were obvious axial splitting cracks in the failure modes of preflawed specimens, while axial splitting cracks were few in the preflawed specimen with a larger flaw inclination angle and none in the intact specimen. These unloading responses indicate that inducing preflaws can reliably reduce the unloading failure strength and promote the cracking process of hard rock during an excavation unloading process. Moreover, inducing preflaws with a smaller inclination angle (e.g., vertical to the unloading direction) will be more helpful for the unloading failure and rock cracking during an excavation unloading process.

ACS Style

Zhenghong Chen; Xibing Li; Lei Weng; Shaofeng Wang; Longjun Dong. Influence of Flaw Inclination Angle on Unloading Responses of Brittle Rock in Deep Underground. Geofluids 2019, 2019, 1 -16.

AMA Style

Zhenghong Chen, Xibing Li, Lei Weng, Shaofeng Wang, Longjun Dong. Influence of Flaw Inclination Angle on Unloading Responses of Brittle Rock in Deep Underground. Geofluids. 2019; 2019 ():1-16.

Chicago/Turabian Style

Zhenghong Chen; Xibing Li; Lei Weng; Shaofeng Wang; Longjun Dong. 2019. "Influence of Flaw Inclination Angle on Unloading Responses of Brittle Rock in Deep Underground." Geofluids 2019, no. : 1-16.

Thematic issue
Published: 12 February 2019 in Environmental Earth Sciences
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In undersea gold mines, the development of a water-flow fracture zone and its connection with the aquifer may cause massive water and sand inrush disasters. In this study, approaches including theoretical analysis, numerical simulation and field detection are employed to identify the development height of the water-flow fracture zone caused by undersea mining in the Xinli Zone of the Sanshandao Gold Mine to ensure mining safety. An improved Winkler elastic foundation beam model, considering the coupled influences of seawater pressure and backfill support, was established to calculate the height of the water-flow fracture zone. The result demonstrates that the height of the water-flow fracture zone depends on the elastic modulus of the overburden strata and the compression modulus of the filling material. Then, an experimental study utilizing a custom-made apparatus is conducted to obtain the Winkler foundation compression characteristics of the filling material used in the gold mining operation. The theoretical analyses are confirmed by numerical simulations and show that the height of the water-flow fracture zone decreases with the increase in mining level because the loads from overburden weight decreases with the mining depth. The theoretical analysis, numerical simulation and field detection present that the height of the mining-induced water-flow fracture zone is 39 m, 37 m, and 40.5–45 m, respectively, after mining at the − 135 m level. These values are reasonably consistent, suggesting that the proposed theoretical and numerical models and the utilized field detection method can provide valuable information for determining the overburden stability of an undersea mineral seam and improving mining safety.

ACS Style

Ying Chen; Guoyan Zhao; Shaofeng Wang; Hao Wu; ShaoWei Wang. A case study on the height of a water-flow fracture zone above undersea mining: Sanshandao Gold Mine, China. Environmental Earth Sciences 2019, 78, 122 .

AMA Style

Ying Chen, Guoyan Zhao, Shaofeng Wang, Hao Wu, ShaoWei Wang. A case study on the height of a water-flow fracture zone above undersea mining: Sanshandao Gold Mine, China. Environmental Earth Sciences. 2019; 78 (4):122.

Chicago/Turabian Style

Ying Chen; Guoyan Zhao; Shaofeng Wang; Hao Wu; ShaoWei Wang. 2019. "A case study on the height of a water-flow fracture zone above undersea mining: Sanshandao Gold Mine, China." Environmental Earth Sciences 78, no. 4: 122.

Review article
Published: 29 October 2018 in Journal of Cleaner Production
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Cleaner production is the continuous application of an integrated preventive environmental strategy which stressed the importance of environment and human beings. Although the application of cleaner production is becoming more and more mature in different industries, since the complexity of the mining operation itself and its extensive and complex impacts on the ecological environment, the application of cleaner production in the mining industry encounters great challenges. For this purpose, the paper presents some developments and new insights of environmental problems and deep mining strategy for cleaner production in mines. Firstly, the general impacts on the ecological environment of mining industry and the current corresponding solutions as well as future prospects are presented. Secondly, the ecological environment pollutions induced by tailings dam and its elimination approaches are reviewed. For the accelerating volume of tailings dam waiting to be processed, the exploration and research of the comprehensive utilization and treatment of tailings is expected to be more effective with larger consumption and wider range of application. The development direction is the establishment of mine without tailings. With the development of modern technology, some intelligent monitoring and warning technologies have helped the mining engineers to keep a vigilant eye on tailings dam continually. Finally, to convert the “harm” of four highs and one disturbance induced by the complex mechanical environment in deep mines into “benefit”, various specific measures with relatively high novelty and sustainability are recommended. Moreover, the conception map of safer and more efficient exploitation of resources in deep mines is depicted for industrial best practice and future research directions to enhance cleaner production work in mining.

ACS Style

Longjun Dong; Xiaojie Tong; Xibing Li; Jian Zhou; Shaofeng Wang; Bing Liu. Some developments and new insights of environmental problems and deep mining strategy for cleaner production in mines. Journal of Cleaner Production 2018, 210, 1562 -1578.

AMA Style

Longjun Dong, Xiaojie Tong, Xibing Li, Jian Zhou, Shaofeng Wang, Bing Liu. Some developments and new insights of environmental problems and deep mining strategy for cleaner production in mines. Journal of Cleaner Production. 2018; 210 ():1562-1578.

Chicago/Turabian Style

Longjun Dong; Xiaojie Tong; Xibing Li; Jian Zhou; Shaofeng Wang; Bing Liu. 2018. "Some developments and new insights of environmental problems and deep mining strategy for cleaner production in mines." Journal of Cleaner Production 210, no. : 1562-1578.

Journal article
Published: 01 September 2018 in Tunnelling and Underground Space Technology
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This study aims to determine the influences of confining stresses and cutting parameters on hard rock fragmentation using a conical pick. Using a true triaxial testing apparatus, single/double pick forces and static/coupled static-dynamic pick forces were applied to granite rock specimens to break them confined by biaxial, uniaxial and no lateral stress conditions. The corresponding cuttabilities were estimated and compared by the peak pick force, insertion depth and disturbance duration at rock failure and the associated failure patterns. The results showed that excavation-induced unloading and cracking, which can change the biaxial confining stress conditions into the uniaxial and decrease uniaxial confining stress level, respectively, can significantly improve the hard rock cuttability. The experimental, theoretical and regressive results indicated that the hard rock cuttability initially decreases and then increases as the level of uniaxial confining stress increased. A moderate uniaxial confining stress instead improves the rock cuttability, but a high stress level may induce rock burst triggered by conical pick penetration. Therefore, only the hard rocks under stress-free and low uniaxial confining stress conditions can be easily fragmented with high safety and efficiency, as a complete splitting failure occurs. In addition, the hard rock cuttability can be also improved by the dynamic pick disturbance and the artificial defects such as excavation-induced fractures, pre-slits and boreholes in rock mass.

ACS Style

Shaofeng Wang; Xibing Li; Kun Du; Shanyong Wang. Experimental investigation of hard rock fragmentation using a conical pick on true triaxial test apparatus. Tunnelling and Underground Space Technology 2018, 79, 210 -223.

AMA Style

Shaofeng Wang, Xibing Li, Kun Du, Shanyong Wang. Experimental investigation of hard rock fragmentation using a conical pick on true triaxial test apparatus. Tunnelling and Underground Space Technology. 2018; 79 ():210-223.

Chicago/Turabian Style

Shaofeng Wang; Xibing Li; Kun Du; Shanyong Wang. 2018. "Experimental investigation of hard rock fragmentation using a conical pick on true triaxial test apparatus." Tunnelling and Underground Space Technology 79, no. : 210-223.

Journal article
Published: 01 September 2018 in Construction and Building Materials
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Rocks are commonly used as building stone and construction materials in many engineering applications. They usually undergo cyclic wetting and drying processes due to the periodical variations in moist conditions. In this paper, to understand the deterioration on the tensile strength of sandstone induced by wetting and drying cycles, dynamic Brazilian disc tests were conducted on sandstone specimens after every 10 cycles (for a total of 50 cycles) under a wide range of loading rates using a modified split Hopkinson pressure bar (SHPB) technique. Test results revealed that at the same loading rate, the dynamic tensile strength of specimens decreased with the number of wetting and drying cycles. Microscopic morphological structure on the sandstone surface were also obtained by scanning electron microscope (SEM), the characteristics and fractal analysis indicated that cyclic wetting-drying treatments would result in accumulative crack damage in rock, which was considered as the primary reason for the reduction in strength. Moreover, a decay model considering the effects of loading rate and cyclic wetting and drying deterioration was established to predict the dynamic tensile strength of sandstone after wetting and drying cycles. The forecast data via the decay model matched the trends of the experimental results well, meaning that the decay model was valid and applicable for the strength prediction.

ACS Style

Zilong Zhou; Xin Cai; Dan Ma; Lu Chen; Shaofeng Wang; Lihai Tan. Dynamic tensile properties of sandstone subjected to wetting and drying cycles. Construction and Building Materials 2018, 182, 215 -232.

AMA Style

Zilong Zhou, Xin Cai, Dan Ma, Lu Chen, Shaofeng Wang, Lihai Tan. Dynamic tensile properties of sandstone subjected to wetting and drying cycles. Construction and Building Materials. 2018; 182 ():215-232.

Chicago/Turabian Style

Zilong Zhou; Xin Cai; Dan Ma; Lu Chen; Shaofeng Wang; Lihai Tan. 2018. "Dynamic tensile properties of sandstone subjected to wetting and drying cycles." Construction and Building Materials 182, no. : 215-232.

Journal article
Published: 01 April 2018 in Transactions of Nonferrous Metals Society of China
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In order to achieve the safe mining in Sanshandao Gold Mine, five schemes of secure pillar group are designed. Using the method of the renormalization group, the failure mechanism of the pillar group is explored, and the safety factor of the pillar system is also obtained. The displacement characteristics, stress–strain laws, distribution of plastic zone and damage range of different pillar group are analyzed using numerical calculation software FLAC3D. To determine a reasonable pillar group scheme, the pillar stability and roof deformation are utilized to evaluate the safety of the pillar group. In addition, the theory of fuzzy comprehensive evaluation is adopted to verify the optimal scheme. The pillar group with the lowest roof deformation value is chosen as the optimal plan, which renders a factor of safety of 2.06 for the pillar group. According to this scheme, pillars with the width of 10 m are set along the strike of undersea deposit with the interval of 50 m. Rib pillars of 15 m in width are set at the location of the exploration line of 127, 151 and 167. The analysis can be used to provide guidance for optimal design of pillar structures in undersea mining.

ACS Style

Zhi-Xiang Liu; Tian Luo; Xiang Li; Xi-Bing Li; Zhen Huai; Shao-Feng Wang. Construction of reasonable pillar group for undersea mining in metal mine. Transactions of Nonferrous Metals Society of China 2018, 28, 757 -765.

AMA Style

Zhi-Xiang Liu, Tian Luo, Xiang Li, Xi-Bing Li, Zhen Huai, Shao-Feng Wang. Construction of reasonable pillar group for undersea mining in metal mine. Transactions of Nonferrous Metals Society of China. 2018; 28 (4):757-765.

Chicago/Turabian Style

Zhi-Xiang Liu; Tian Luo; Xiang Li; Xi-Bing Li; Zhen Huai; Shao-Feng Wang. 2018. "Construction of reasonable pillar group for undersea mining in metal mine." Transactions of Nonferrous Metals Society of China 28, no. 4: 757-765.

Original paper
Published: 14 March 2018 in Rock Mechanics and Rock Engineering
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High geostresses and stress gradients are the predominant stress conditions in deep excavation-disturbed rock masses. The aim of this study is to determine the triaxial compressive strength properties of hollow cylindrical granite specimens under a radially non-uniform confining stress field with different radial stress gradients determined by coupled external and internal confining stresses. Triaxial compression testing of hollow cylindrical rock specimens was performed to investigate the influence of the radial stress gradient, external confining stress and specimen length-to-diameter (L/D) ratio on the triaxial compressive strength. The experimental results and regressed failure criteria indicate that the triaxial compressive strengths of the hollow cylindrical granite specimens increase with the external confining stresses, but decrease with an increase in the radial stress gradients. The calculated goodness of fit (R2) and root-mean-squared error suggest that the nonlinear failure criterion based on the Hoek–Brown model is more accurate than the linear failure criterion based on the Mohr–Coulomb model for determining the influences of the external confining stress and radial stress gradient on the triaxial compressive strength. In addition, the triaxial compressive strength increases with a decreasing L/D ratio due to the strengthening end effect of the hollow cylindrical granite specimens and the change in the failure pattern of these specimens from shear to slabbing.

ACS Style

Shaofeng Wang; Xibing Li; Kun Du; Shanyong Wang; Ming Tao. Experimental Study of the Triaxial Strength Properties of Hollow Cylindrical Granite Specimens Under Coupled External and Internal Confining Stresses. Rock Mechanics and Rock Engineering 2018, 51, 2015 -2031.

AMA Style

Shaofeng Wang, Xibing Li, Kun Du, Shanyong Wang, Ming Tao. Experimental Study of the Triaxial Strength Properties of Hollow Cylindrical Granite Specimens Under Coupled External and Internal Confining Stresses. Rock Mechanics and Rock Engineering. 2018; 51 (7):2015-2031.

Chicago/Turabian Style

Shaofeng Wang; Xibing Li; Kun Du; Shanyong Wang; Ming Tao. 2018. "Experimental Study of the Triaxial Strength Properties of Hollow Cylindrical Granite Specimens Under Coupled External and Internal Confining Stresses." Rock Mechanics and Rock Engineering 51, no. 7: 2015-2031.