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Research on gas diffusion model and experimental diffusion characteristic of cylindrical coal

Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology 2017年第5期46卷 1033-1040页

作者： Li, Zhiqiang Cheng, Qiang Liu, Yanwei Duan, Zhengpeng Song, Dangyu State Key Laboratory of Coal mine Disaster Dynamics and Control Chongqing University Chongqing400030 China Henan Polytechnic University JiaozuoHenan454000 China MOE Engineering Center of Mine Disaster Prevention and Rescue Henan Polytechnic University JiaozuoHenan454000 China Henan Provincial Key Lab of Gas Geology and Control-Cultivation Base of Provincial and Ministry Joint State Key Henan Polytechnic University JiaozuoHenan454000 China

Under various temperatures and pressures, the gas diffusion experiments were carried out with Φ50 mm×100 mm standard cylindrical coal samples. At the same time, a gas diffusion experiment was carried out by use of the particles of the same coal as comparative experiment. To describe the gas diffusion in cylindrical coal samples, the cylindrical diffusion model was established and the analytical solution of diffusion rate was derived. The results show that the gas diffusion in cylindrical raw coal is slower than that in coal particles. And the cumulative diffusion quantity and diffusivity in cylindrical raw coal is far less than those in coal particles under the same time. The diffusion coefficient of cylindrical raw coal is 11.72 times as much as that of coal particles. This is because that the cylindrical row coal contains a larger pore and fissure diamaters. But the effective diffusion coefficient of cylindrical raw coal is 1.82% of which in coal particles. That results from the extension of the diffusion path and the increase of the tortuosity. These lead the cylindrical coal core to contain a smaller capacity of release gas. © 2017, Editorial Board of Journal of CUMT. All right reserved.

关键词： Coal

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Rheological Behaviors of Fresh Cement Pastes with Polycarboxylate Superplasticizer

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Journal of Wuhan University of Technology(Materials Science) 2016年第2期31卷 286-299页

作者：张艳荣孔祥明高亮 WANG Jiaxin State Key Lab of Rail Traffic Control and Safety School of Civil Engineering beijing Jiaotong University beijing 100044 China Department of Civil Engineering Tsinghua University Beijing 100084 China beijing Key Laboratory of Track Engineering beijing Engineering and Technology Research Center of Rail Transit Line Safety and Disaster Prevention Beijing Jiaotong University Beijing 100044 China

The rheologicalbehaviors of fresh cement paste with polycarboxylate superplasticizer were systematically *** including superplasticizer to cement ratio（Sp/C）,water to cement ratio（w/c）,temperature,and time were *** cement pastes with Sp/Cs in the range of 0 to 2.0% and varied W/Cs from 0.25 to 0.5 were prepared and tested at 0,20 and 40 °C,*** and rheologicaltests on cement pastes were conducted to characterize the development of the rheologicalbehavior of fresh cement pastes over *** exprimentalresults indicate that the initialflowability and flowability retention over shelf time increase with the growth in superplasticizer dosage due to the plasticizing effect and retardation effect of *** temperature usually leads to a sharper drop in initialflowability and flowability ***,for the cement paste with high Sp/C or w/c,the flowability is slightly affected by *** stress and plastic viscosity show similar variation trends to the flowability under the abovementioned influentialfactors at low Sp/*** the case of high Sp/C,yield stress and plastic viscosity start to decline over shelf time and the decreasing rate descends at elevated ***,two equations to roughly predict yield stress and plastic viscosity of the fresh cement pastes incorporating Sp/C,w/c,temperature and time are developed on the basis of the existing models,in which experimentalconstants can be extracted from a database created by the rheologicaltest results.

关键词： cement paste flowability yield stress plastic viscosity model

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THE EFFECTS OF THREE-DIMENSIONAL PENNY-SHAPED CRACKS ON ZONAL DISINTEGRATION OF THE SURROUNDING ROCK MASSES AROUND A DEEP CIRCULAR TUNNEL

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Acta Mechanica Solida Sinica 2015年第6期28卷 722-734页

作者： Xiaoping Zhou Qihu Qian Hanfei Song School of Civil Engineering Chongqing University State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Engineering Institute of National Defense Engineering PLA University of Science and Technology State Key Laboratory of Disaster Prevention & Mitigation of Explosion & Impact PLA University of Science and Technology

In this study, it was assumed that three-dimensional penny-shaped cracks existed in deep rock masses. A new non-Euclidean model was established, in which the effects of penny- shaped cracks and axial in-situ stress on zonal disintegration of deep rock masses were taken into account. Based on the non-Euclidean model, the stress intensity factors at tips of the penny- shaped cracks were determined. The strain energy density factor was applied to investigate the occurrence of fractured zones. It was observed from the numerical results that the magnitude and location of fractured zones were sensitive to micro- and macro-mechanical parameters, as well as the value of in-situ stress. The numerical results were in good agreement with the experimental data.

关键词： deep rock masses containing penny-shaped cracks the non-Euclidean model axial in-situ stress fractured zones zonal disintegration phenomenon deep circular tunnel

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Two-dimensional analyses of delamination buckling of symmetrically cross-ply rectangular laminates

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Applied Mathematics and Mechanics(English Edition) 2013年第5期34卷 597-612页

作者：薛江红罗庆姿韩峰刘人怀 Department of Mechanics and Civil Engineering Jinan University Key Lab of Disaster Forecast and Control in Engineering Ministry of Education Beijing Institute of Technology State Key Laboratory of Explosion Science and Technology

The conventional approach to analysis the buckling of rectangular laminates containing an embedded delamination subjected to the in-plane loading is to simplify the laminate as a beam-plate from which the predicted buckling load decreases as the length of the laminate increases. Two-dimensional analyses are employed in this paper by extending the one-dimensional model to take into consideration of the influence of the delamination width on the buckling performance of the laminates. The laminate is simply supported containing a through width delamination. A new parameterβ defined as the ratio of delamination length to delamination width is introduced with an emphasis on the influence of the delamination size. It is found that （i） when the ratio β is greater than one snap-through buckling prevails, the buckling load is determined by the delamination size and depth only; （ii） as the ratio β continues to increase, the buckling load will approach to a constant value. Solutions are verified with the well established results and are found in good agreement with the latter.

关键词： two-dimensional analysis rectangular laminate delamination buckling laminate theory

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Numerical simulation of electric field characteristics in response to water in-rush in working face

Numerical simulation of electric field characteristics in re...

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作者： Cheng, Jiulong Sui, Haibo Wang, Yuhe Cai, Mingfeng Jiang, Guoqing State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology Beijing 100083 China Key Laboratory of Mine Disaster Prevention and Control Shandong University of Science and Technology Qingdao 266510 China Key Lab. for the Exploitation of Southwestern Rsrc. and the Environ. Disaster Control Engineering Ministry of Education Chongqing 400044 China CPECC East China Design Branch Qingdao 266071 China

ISBN: (纸本)9789078677383

According to the principle of resistivity detecting method and influencing law of resistivity in mining affected floor strata, different geoelectric models were constructed, such as model with water in-rush fractured zone in floor, working face advances to different distances, water in-rush after mining. Based on the "bipole-dipole" device, forward modeling was carried out by three-dimensional finite difference method. Apparent resistivity curves of different models can be obtained through numerical calculation and CT images can be obtained by processing the resistivity data with computerized tomography. Response characteristics of electric field in water in-rush working face can be analyzed by combing apparent resistivity curves with CT images. The results show that: good geological results could be achieved through numerical simulation of electric field response characteristics by using finite difference method and analyzing electric field characteristics of water in-rush in working face. This study provides theoretical basis for water in-rush detection using the resistivity method. © Atlantis Press, 2010.

关键词： Computerized tomography

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Radial dispersion angle of directional fragments in multi-mode warhead

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Jiefangjun Ligong Daxue Xuebao/Journal of PLA University of Science and Technology (Natural Science Edition) 2010年第4期11卷 468-472页

作者： Zhang, Yang-Yi Long, Yuan Yu, Dao-Qiang Ji, Chong Zhong, Ming-Shou Engineering Institute of Corps of Engineers PLA Univ. of Sci. and Tech. Nanjing 210007 China State Key Laboratory of Prevention and Control of Explosion Disaster Beijing Institute of Technology Beijing 100081 China The First Research Institute of the Corps of Engineers Wuxi 214035 China

To investigate the characteristics of directional fragments mode in multi-mode warhead, a charge configuration with an ejectable incisory cover fixed at a proper place before the liners was analyzed. The process of the liner forming directional fragments by passing through two different kinds of incisory covers was simulated using LS-DYNA3D. Simulation results coincided well with the experimental data. This charge structure can form fragments with a definite mass and direction, and a velocity between 1 500 m/s and 2500 m/s. A Formula of the radial dispersion angle (α) of fragments was got. Influences of the diameter (D), the yield strength of the incisory wire and the distance between the incisory cover and the liner (d) on α were discussed. It's proved that the bigger D, the larger α;that the bigger the yield strength, the more benefit to the forming of fragments, yet with little influence on α;and that d should be in a proper range in order to form ideal fragments, and it has an optimum value.

关键词： Yield stress

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Effective viscoelastic behavior of particulate polymer composites at finite concentration

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Applied Mathematics and Mechanics(English Edition) 2007年第3期28卷 297-307页

作者：李丹胡更开 Department of Applied Mechanics Beijing Institute of Technology National Key Lab for the Prevention and Control of Explosion Disaster Beijing Institute of TechnologyBeijing 100081P.R.China

Polymeric materials usually present some viscoelastic behavior. To improve the mechanical behavior of these materials, ceramics materials are often filled into the polymeric materials in form of fiber or particle. A micromechanical model was proposed to estimate the overall viscoelastic behavior for particulate polymer composites, especially for high volume concentration of filled particles. The method is based on Laplace transform technique and an elastic model including two-particle interaction. The effective creep compliance and the stress and strain relation at a constant loading rate are analyzed. The results show that the proposed method predicts a significant stiffer response than those based on Mori-Tanaka＇s method at high volume concentration of particles.

关键词： particulate polymer composite viscoelasticity micromechanics finite concentration

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Theoretical study on the dynamic boundary of hot fluid-solid coupling seepage

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Xi'an Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of Xi'an Shiyou University, Natural Sciences Edition 2007年第2期22卷 119-122页

作者： Wang, Jian-Xing Dong, Qin-Xi College of Architecture and Civil Engineering North China University of Technology Beijing 100041 China State Key Lab. for the Prevention and Control of Explosion Disaster Beijing University of Technology Beijing 100081 China Department of Civil Engineering Chuo University Tokyo 192-0393 Japan

On the basis of Biot theory, the basic equations on the hot fluid-solid coupling seepage are derived, and the mathematical model describing the thermal seepage is established. The dynamic dispersion distributing probability formula of the hot fluid and its coefficient expressions are presented. The displacement field of micro-pressure hot fluid is established, and the effect of the dynamic dispersion of the hot fluid on the boundary of porous media is discussed, and the equations for describing the dynamic boundary of porous media are established. In accordance with different outer factors, four boundary models and their dynamic simulations are presented.

关键词： Hot fluid-solid coupling Porous medium Thermo-saturation zone

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An analysis on dynamic damage on concrete obstruct subjected to underwater explosion shock waves

An analysis on dynamic damage on concrete obstruct subjected...

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作者： Hao, Li Ning, Jian-Guo Beijing Institute of Civil Engineering and Architecture Beijing 100044 China State Key Lab for the Prevention and Control of Explosion Disaster Beijing Institute of Technology Beijing 100081 China

Based on the multi-material Eulerian algorithm, the damage effects of concrete obstruct subjected to underwater explosion shock waves are simulated by using the NM-MMIC code which is a 2D multi-material elastic-plastic hydrodynamics code with C++ language. According to the simulation results of underwater explosion, the optimum charge, the damage degree and the damage laws of obstruct are obtained. The simulation results show a good agreement with that obtained by DYNA2D. Thus the given study indicates that the model and algorithm presented in this paper are reasonable and the simulation method can be used for designing and estimating ammunitions against obstructs in water.

关键词： Concrete construction

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An experimental study on creep deformation of PBX with laser moiré interferometry method

An experimental study on creep deformation of PBX with laser...

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作者： Xie, Huimin Shi, Hang Chen, Pengwan Huang, Fenglei Fang, Daining Dept. of Eng. Mechanics Tsinghua University Beijing 100084 China State Key Lab of Prevention and Control of Explosion Disasters Beijing Institute of Technology Beijing 100081 China

In this paper, the creep deformation of PBX was measured using the moiré interferometry. The experimental results show a different creep process compared with pure high polymer and this phenomenon is preliminary ... 详细信息

关键词： Creep

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