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Research on eddy air-curtain dust controlled flow field in hard rock mechanized driving face

Journal of Networks 2013年第2期8卷 453-460页

作者： Cheng, Wei-Min Wen, Nie Zhou, Gang Yang, Jun-Lei College of Resource and Environmental Engineering Shandong University of Science and Technology Qingdao China Key Laboratory of Mining Disaster Prevention and Control Ministry of Education Shandong University of Science and Technology Qingdao China

The mathematical model of single-phase flow of gas was established based on the k-Ε two-equation model and numerically simulated the eddy air-curtain dust controlled flow field in hard rock mechanized driving face with the help of FLUENT software on account of the collocated grid SIMPLE algorithm. The result showed that, after all the pressure ventilation blown out by the radial clearance of mural cylinder, a full-face eddy air-curtain flow field is formed at the roadway section and with the help of the exhausting cylinder, it keeps pushing toward the tunneling place, forming the air-curtain dust controlled flow field that presses the tunneling place equally in front of the driver of road header. After the application of the development of new light polymer materials radial cylinder eddy air-curtain dust controlled system was adopted in hard rock mechanized driving face of north conveyor main roadway, the average settlement rate of total dust and repairable dust have reached to 97.4% and 96.8% respectively, reducing the local dust concentration effectively. © 2013 ACADEMY PUBLISHER.

关键词： Flow fields

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Structural damage detection using response phase space for beam-like structure under a moving load

Structural damage detection using response phase space for b...

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20th International Congress on Sound and Vibration 2013, ICSV 2013

作者： Nie, Zhenhua Jiang, Hui Ma, Hongwei College of Science and Engineering Jinan University Guangzhou Guangdong 510632 China Seismological Bureau of Guang Dong Province Guang Zhou Guang Dong China Key Laboratory of Disaster Forecast and Control in Engineering Ministry of Education of China Guangzhou Guangdong 510632 China

ISBN: (纸本)9781629931500

Ideally, structural health monitoring of civil infrastructure consists of determining, by measured parameters, the location and severity of damage in the structure. Many structural Vibration parameters have been used to identify and quantify damage. Using parameters based on structural Vibration phase space features for damage detection is a new field in structural health monitoring. In this paper, a new damage detection method based on phase space of a single response is proposed. Firstly, the defmition of phase space of Vibration system is introduced. Then a new damage index named CPST (changes of phase space topology) based on topology changes of the phase space of Vibration signals under a moving load is introduced. The phase space of the dynamic response is constructed by the velocity and acceleration responses. The CPST values are calculated from the constructed phase space and used to identify structural damage. The main idea is that when the moving load passing by the damage location, the CPST curves have a singular point, which is used to locate the damage location. To demonstrate the method, the dynamic responses of a point on a beam-like structure are measured under different damage severity are used to calculate CPST for damage detection. The results indicate the CPST curves can successfully identify damage location and quantification. The proposed method is a good candidate for damage detection since only one sensor is needed.

关键词： Damage detection

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Decline in gas pressure influences the deformation and permeability of coal-containing methane

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Computer Modelling and New Technologies 2014年第6期18卷 342-347页

作者： Tao, Yunqi Liu, Dong Cao, Jie Xu, Jiang School of Energy Science and Engineering Henan Polytechnic University Jiaozuo Henan Province China Yongcheng Coal and Electricity Holding Group Co. Ltd. Yongcheng Henan Province China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Chongqing China

The development and utilization of coal-bed methane, as an unconventional gas, is not only beneficial to the reduction of environmental pollution caused by fossil fuels, but also conducive to the prevention of disasters during coal mining. In this paper, a dynamic permeability model of coal body is established and discussed by means of experimental tests, which measure the deformation and gas permeability of coal-containing methane in the process of gas pressure reduction under different temperatures. The results show that, when gas pressure decreases, the strain of coal-containing methane increases linearly. With temperature increases, the variation of radial strain decreases. Under the same temperature, the permeability of coal decreases first and then increases again during gas pressure reduction. The changing point of gas pressure is approximately 1.2 MPa in the study. In the initial stage of gas pressure decrease, the radial strain of coal-containing gas has a significant effect on its permeability.

关键词： Coal

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Numerical simulation of the oblique crack in the pipes using a chaotic oscillator based on ultrasonic guided wave

Numerical simulation of the oblique crack in the pipes using...

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20th International Congress on Sound and Vibration 2013, ICSV 2013

作者： Yang, Fei Jing, Lin Zhang, Weiwei Lin, Rong Ma, Hongwei College of Science and Engineering Jinan University Guangzhou 510632 China Impact Mechanics Laboratory Department of Mechanical Engineering National University of Singapore Singapore 117576 Singapore Department of Mechanics Taiyuan University of Science and Technology Taiyuan 030024 China Moe Key Laboratory of Disaster Forecast and Control in Engineering Jinan University Guangzhou 510632 China

ISBN: (纸本)9781629931500

The ultrasonic longitudinal guided waves in oblique cracked pipes were investigated using finite element software LS-DYNA 3D in this paper. Based on the improved Duffing chaotic oscillator with substitution of (-x3+x5) for (-x+x3) of the non-linear restoring force item, a novel inspection method was proposed. Four kinds of defects with inclined angle of 15°, 30°, 45°and 90° were analyzed, respectively. Numerical results show that the proposed method could be used to inspect weaker guided waves, and the amplitude of echo increases with the decrease of the inclined angle. The results are worthy of engineering application in both extending guided waves detection range and increasing the sensitivity of detecting micro oblique crack.

关键词： Guided electromagnetic wave propagation

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Experiment and Research of Chemical De-dusting Agent with Spraying Dust-settling

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Procedia engineering 2014年 84卷 764-769页

作者： Wang Naiguo Nie Wen Cheng Weimin Liu Yanghao Zhu Liang Zhang Lei State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Safety Technology Shandong University of Science and Technology Qingdao 266590 Shandong China College of Mining and Safety Engineering Shandong University of Science and Technology Qingdao 266590 Shandong China New Julong Energy Resource Co. Ltd. Juye 274918 Shandong China

In order to improve binding capacity between water and dust and the efficiency of dust removal in spray, in this paper, the surface tensions and contact angles of four surfactant solutions, such as SDS, CAB-35, JFCS and BS-12, in different concentrations were tested by using automatic surface tensiometer and video optical contact angle measuring instrument, determining their CMC, which was also the concentration ratio of the four surfactant solutions; By the principle of each two single surfactant's combination, coal dust settling and up-ward seepage experiments of the six combination solutions were conducted, combined with simulation experiment, determining that the optimum surfactant agent used for de-dusting was the combination of these two surfactants: CAB-35 and JFCS, in the mass fraction of 0.05%. Meanwhile, it was also applied in fully mechanized heading face of 2th mining area of Xin Zhi coal mine, Huozhou Coal Electricity Group, Shanxi Coking Coal Group.

关键词： surfactants CMC composite stabilizer experiment spraying simulation

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Mechanical property and permeability of raw coal containing methane under unloading confining pressure

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International Journal of Mining Science and Technology 2013年第6期23卷 789-793页

作者： Yin Guangzhi Li Wenpu Jiang Changbao Li Minghui Li Xing Liu Hairu Zhang Qiangui State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University College of Resources and Environmental Sciences Chongqing University State and Local Joint Engineering Laboratory of Methane Drainage in Complex Coal Gas Seam School of Petroleum Engineering Southwest Petroleum University

Based on domestic-developed triaxial servo-controlled seepage equipment for thermal-hydrologicalmechanical coupling of coal containing methane,an experimental study was carried out to investigate mechanical property and gas permeability of raw coal,under the situation of conventional triaxial compression and unloading confining pressure tests in different gas pressure *** unloading confining pressure process was reducing confining pressure while increasing axial *** research results show that,compared with the peak intensity of conventional triaxial loading,the ultimate strength of coal samples of triaxial unloading confining pressure was lower,deformation under loading was far less than unloading,dilation caused by unloading was more obvious than *** change trend of volumetric strain would embody change of gas permeability of coal,the permeability first reduced along with volumetric strain increase,and then raised with volume strain decrease,furthermore,the change trends of permeability of coal before and after destruction were different in the stage of decreasing volume strain due to the effect of gas *** gas pressure was greater,the effective confining pressure was smaller,and the radial deformation produced by unloading was *** the unloading failed confining pressure difference was smaller,coal would be easier to get unstable failure.

关键词： Mining engineering Unloading confining pressure Coal containing methane Mechanical property Permeability

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Numerical modelling of rock cross-cut coal uncovering based on ANSYS

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Computer Modelling and New Technologies 2014年第3期18卷 26-32页

作者： Wang, G. Wang, H.Y. Huang, Q.M. Su, C.Q. State Key Laboratory of Ministry of Mining Disaster Prevention and Control Shandong University of Science and Technology Qingdao Shandong 266590 China College of Resources and Environmental Engineering Shandong University of Science and Technology Qingdao Shandong 266590 China Lindong Mining Group Co. Ltd. Guiyang Guizhou 550056 China

Outbursts of coal and gas could be induced by rock cross-cut coal uncovering. ANSYS is used to numerically simulate the stress, strain and energy of surrounding rock of roadway during the process of rock cross-cut coal uncovering. Modelling results show that there is a banding tension stress zone in roof and floor of roadway after excavation. Principal and shear stress concentration are formed in the upper and under area of the anterior heading face, which is symmetrically distributed between medial axis of roadway, while stress, strain and strain energy of overlying strata above the coal seam approximately keep invariant. The occurrence of the stress concentration in upper area of the anterior heading face could contribute to the instability and failure of coal and rock mass. The area with weak destruction-resisting ability is the most easily to be the releasing port of outburst and should be regarded as the key region in outburst prevention.

关键词： Stress concentration

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Analysis of reinforced slope based on interface properties of geosynthetics and soil

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Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical engineering 2013年第SUPPL.2期35卷 217-223页

作者： Liu, Dong Chen, Xiao-Ping Chang, Xue-Ning College of Science and Engineering Jinan University Guangzhou 510632 China Key Laboratory of Disaster Forecast and Control in Engineering Jinan University Guangzhou 510632 China Guangdong Hydropower Planning and Design Institute Guangzhou 510170 China

As the geosynthetics are widely used in engineering practice to strengthen the slope stability, the interaction behaviors of geosynthetics and soil are very important for the slope stability analysis. A reinforced seawall constructed in coast reclamation project in Guangdong Province is analyzed. The interface friction properties of reinforcing materials and filling sand are studied by means of the laboratory shear tests and theoretical analyses, and the reinforcement mechanism is discussed. The numerical calculation is carried out on the stability and deformation behaviors of the reinforced slope under geostatic pressure. The test results show that the shear stress-shear displacement relationship of geosynthetics-soil interface is strain-harding. It is important for the stability of slope in soft foudation. In addition, the density of filling sand is the key factor for the frictional characteristics of interface. The stability analysis shows that the pavement method of reinforcing materials will directly affect the factor of safety of slope stability, and multilayer pavement effect is not a simple addition for every layer. Based on the circular slip surface method, the calculated factor of safety may be too small to reflect the contribution of geosynthetics, the strength reduction method is more reasonable for considering the interface friction. The finite element analysis also reveals that the effect of reinforcement on deformation behaviors of slope is mainly in the restriction to the magnitude of lateral deformation.

关键词： Shear stress

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Attenuation law of elastic modulus of weakly consolidated soft rock

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Electronic Journal of Geotechnical engineering 2013年 18 V卷 5435-5448页

作者： Zhao, Zeng-Hui Wang, Wei-Ming Pan, Guo-Feng Lv, Xian-Zhou State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province Ministry of Science and Technology Shandong University of Science and Technology Qingdao China College of Civil Engineering Shandong University of Science and Technology Qingdao China

It has become very important to make clearly the attenuation law of elastic modulus of weakly consolidated soft rock in the process of damage for engineering. This can provide theoretical basis for the stability maintenance of soft rock tunnel in western mining areas. Based on the actual stress-strain relation and effective stress-strain curve, it was found that Lemaitre's equivalent strain assumption was only applicable to describe the elastic damage, and showed certain limitations to weakly consolidated soft rock. Damage is caused under the interaction of plastic deformation and damage mechanism. The damage threshold point of soft rock coincides with the position of the yield point from where the elastic modulus starts to decay. According to the damage probability distribution theory of rock micro-unit, a new constitutive model was established. Although the model does not consider the plastic behavior of rock mass and only refers to elastic damage, plastic deformation curve can be derived which is effectively extracted from the damage mechanism. Therefore, the attenuation equation of elastic modulus was developed and the correlation between equation parameters a, b, α and confining pressure σ3 were analyzed. The results showed that degradation speed of damage modulus is related to confining pressure. When σ3 &le 3MPa, the yield stage is not obvious. Rock mass mainly suffered from damage mechanism of σ3 > 3MPa. Larger deformation is developed in the yield stage, which shows obvious plastic deformation mechanism. The post-peak behavior is mainly dominated by damage mechanism. The conclusions lay a solid theoretical basis for further study the strength attenuation law of this kind of rock mass. © 2013, EJGE.

关键词： Elastic moduli

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Effective Elastic Moduli of Fiber-reinforced Polymer Matrix Composites Filled with Nano-particle

Effective Elastic Moduli of Fiber-reinforced Polymer Matrix ...

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2013 2nd International Conference on Mechanical Properties of Materials and Information Technology(ICMPMIT 2013)

作者： Hui Zhang Zong-fu Zhang Jia-chu Xu Department of Mechanics and Civil Engineering Jinan University Key Lab of Disaster Forecast and Control in Engineering Ministry of EducationJinan University

Effective moduli of fiber-reinforced polymer matrix composites filled with nano-particle considering the effect of linear change of interphase are presented in this paper. The three-phase inclusion problem for matrix-interface-particle is equivalent to the Eshelby two-phase inclusion problem. According to the result of the Eshelby inclusion problem, the effective modulus tensor of unit cell of equivalent particle is derived. The effective moduli of equivalent matrix are given based on Mori-Tanaka method. Using two fundamental equation of micromechanic theory, the three-dimensional bridged formulation of unidirectional composites is derived. The quantitative relationship between the macroscopic elastic parameters and the structural parameters of the fiber-reinforced polymer composites filled with nano-particles is investigated. Effects of the thickness of interfacial layer, the particle size and the volume fraction of nanoparticles on the effective elastic moduli of the composites are also discussed.

关键词： Nano-particles Interface phase Composite materials Effective modulus Homogenization method

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