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Three-dimensional cellular automata based particle flow simulations of mechanical properties of talus deposit

Journal of Rock Mechanics and Geotechnical Engineering 2012年第4期4卷 375-384页

作者： Linwei Wang Weiya Xu Anquan Xu Geotechnical Research Institute Hohai University College of Hydraulic and Environment Engineering China Three Gorges University Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University

Based on three-dimensional cellular automata （CA）, a new stochastic simulation model to simulate the microstructures and particle flow of talus deposit is proposed. Ill addition, an auto-modeling program CARS is developed, with which nunaerical simulations can be conducted conveniently. For the problem of simulating mechanical behaviors of talus deposit, spatial anangement or sphere shapes should be considered. In the new modeling method, four sphere anangement models are developed for the particle flow simulation of talus deposit. Numerical results show that the talus deposit has the mechanical characteristics of typical stress-strain curves, as other rock-like materials. The cohesion of talus deposit decreases with increasing rock content, while the internal friction angle increases with increasing rock contents. Finally, numerical simulation is verified with the results of field test.

关键词： soil mechanics talus deposit： three-dimensional cellular automata （CA） particle flow mechanical properties

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STUDY ON MESO-MECHANICAL SIMULATION OF GROUTING FOR UNFAVORABLE GEOLOGICAL CONDITIONS

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工程力学 2023年第S1期40卷 248-258页

作者：秦鹏飞钟宏伟刘坚 Department of Engineering Huanghe University of Science and TechnologyZhengzhou 451000China Key Laboratory of Geotechnical Mechanics and Dam Engineering of the Ministry of Education Hohai UniversityNanjing 370000China School of Railway Engineering Zhengzhou Railway Vocational and Technical CollegeZhengzhou 451000China

The numerical simulation program of PFC2D(particle flow Code in 2 Dimension)particle flow based on the flow-solid coupling principle and,on its built-in FISHTANK function library and FISH language,defines the flow equation and pressure equation of fluid domain respectively,and carries out numerical simulation calculations on the diffusion process and,on the morphology and particle displacement of slurry during the slurry injection process.By adjusting the parameters of hist,n_bond,s_bond and measure in the PFC command flow,the tracking of granular body displacement changes is achieved,and the mesoscopic mechanism such as the diffusion law of soil slurry at different depths and the change of formation porosity is revealed.The numerical calculations show that:the grouting pressure has a significant effect on the alteration and destruction of the formation structure,and the fracturing effect becomes gradually worse with increasing adhesive strength,while the porosity increases significantly with increasing grouting pressure.Based on the elastic-plastic theory of the Mohr-Colomb criterion to theoretically derive the stress field of the soil around the borehole,it is pointed out that the mechanical mechanism of annular tension and radial compression is the fundamental reason for the appearance of fracturing grouting action mode.The increase of slurry viscosity is beneficial to improve the grouting effect of fracturing-compacting grouting,while the increase of friction coefficient has little effect on the grouting effect.The comparative analysis of the laboratory tests shows that the PFC2D simulation of the grouting process is feasible.

关键词： formation grouting particle flow numerical simulation meso-analysis slurry diffusion study soil foundation mechanics calculation

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Effects of volumetric fraction and included angle of composite particles on the discharge of binary mixtures in hoppers

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Particuology 2020年第4期18卷 80-90页

作者： Liange Ge Nan Gui Xingtuan Yang Jiyuan Tu Shengyao Jiang Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and SafetyMinistry of EducationTsinghua UniversityBeijing 100084China School of Engineering RMIT UniversityMelbourneVIC 3083Australia

The discharge behavior of particles is important in many industrial applications,such as in the core of a pebble bed reactor,which uses a hopper bed filled with many large particles.In this work,a mixture composed of two particle types,freely discharged from a pebble bed,is simulated using the discreteelement method.One is a spherical pebble of diameter equal to that of the fuel pebble of the reactor.The other is a composite particle comprising three spherical pebbles bonded together.The included angleαof the three pebbles characterized the particle conformation,which may affect the discharge behavior of the mixture.The effects of volume fraction of the multi-sphere x(equivalent to the number fraction)on the discharge are also analyzed.flow patterns,number flow rate,discharge velocity,and mean force of the mixture are computed to help in revealing discharge features.The results show that increasing eitherαor x reduces the discharge flow rate.Fittings and correlations give a quantitative evaluation of the independent effects ofαand x.The analysis of velocity and force explains the mechanism relevant to the main influencing factorsαand x.The results are helpful in gaining a better understanding of the discharge feature of binary mixtures and in providing a quantitative evaluation of the discharge behavior of the reactor core,especially adverse failure conditions.

关键词： Pebble flow particle flow Discharge flow Hopper bed Binary mixture Discrete element method

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Microscopic Simulation of Expansive Soils and Evolution Laws

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Fluid Dynamics & Materials Processing 2020年第6期16卷 152-161页

作者： Lin Pan Jinhong Xia Hongxing Han School of Civil Engineering and Architecture Xinxiang UniversityXinxiang453003China

In this paper,the discrete element method(DEM)is used to study the microstructure of expansive soils.The results of the numerical calculations are in agreement with the stress-strain triaxial test curve that is obtained for a representative expansive soil.Biaxial compression tests are conducted for different confining pressures(50 kpa,100 kpa,and 150 kpa).Attention is paid to the following aspects:deviatoric stress,boundary energy,friction energy,bond energy,strain energy,kinetic energy,and the contact force between grains when the test specimen is strained and to the effect of the different confining pressures on the internal crack expansion.The results of this research show that the cross-section of the specimen is destroyed along the middle part of the specimen itself.When the confining pressure is higher,the impulse is stronger,and this leads to more effective destruction.

关键词： Expansive soil particle flow parallel-bond crack

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STUDY ON MESO-MECHANICAL SIMULATION OF GROUTING IN BAD GEOLOGICAL BODIES

STUDY ON MESO-MECHANICAL SIMULATION OF GROUTING IN BAD GEOLO...

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第31届全国结构工程学术会议

作者：秦鹏飞 YANG Liu FAN Miao CHEN Xiao-hong Key Laboratory of Mechanics on Disaster and Environment in Western China The Ministry of Education of ChinaLanzhou University School of Railway Engineering Zhengzhou University of Railway Vocational Technology

It is an important method to study the deformation and stress characteristics of discrete media such as rock and soil from the perspective of mesomechanic, and the PFC2D numerical simulation test technology based on the theory of mesomechanic can reveal the development dynamics of the grouting process such as the distribution of tensile and compressive stress fields, the deformation movement of soil particles and their coupling process with slurry during grouting from a mesoscopic perspective, which provides a new way for the analysis and research of grouting reinforcement of weak soil, weathered rock and fractured zone. In this paper, the numerical simulation program of PFC2D particle flow based on the flow-solid coupling principle, and using its built-in FISHTANK function library and FISH language, defines the flow equation and pressure equation of fluid domain respectively, and carries out numerical simulation calculations on the diffusion process, morphology and particle displacement of slurry during the slurry injection process. By adjusting the parameters of hist, nond, sond and measure in the PFC command flow, the tracking of granular body displacement changes is achieved, and the mesoscopic mechanism such as the diffusion law of soil slurry at different depths and the change of formation porosity is revealed. The numerical calculations show that, the grouting pressure has a significant effect on the alteration and destruction of the formation structure, and the fracturing effect becomes gradually worse with increasing adhesive strength, while the porosity increases significantly with increasing grouting pressure. Based on the elastic-plastic theory of Mohr-Colomb criterion to theoretically derive the stress field of the soil around the borehole, it is pointed out that the mechanical mechanism of annular tension and radial compression is the fundamental reason for the appearance of fracturing grouting action mode. The increase of slurry viscosity is beneficial to improve the grouting effect of fracturing-c

关键词： formation grouting particle flow numerical simulation meso-analysis slurry diffusion

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Numerical Simulation of a Turbine Meter for measuring Bulk Solids flow-rate

Numerical Simulation of a Turbine Meter for measuring Bulk S...

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The Sixth International Conference on Measurement and Control of Granular Materials

作者： Guoxian Xiao Delong Xu Yanxin Chen A.B.Yu Xi’an University of Architecture and Technology,Xi’an,China 710055 University of New South Wales,Australia,2052

The turbine meter used for metering solids re-circulating flow-rate in Circulating Fiuidized Bed is numerically simulated by the Discrete Element Method The simulation results indicate that the working process of the turbine meter consists of two stages: initial acceleration and stea@ rotation.The final rotation rate of the turbine at the end of the acceleration stage depends on the mass flow rate of particles.The relationship between solids mass flow rate and the rotation rate of the turbine is linear.For comparison data of the rotation rate and mass flow rate was measured by experiments and documented The influence of blade number and blade angle on the relationship is also examined

关键词： Numerical Simulation particle flow Turbine flow Meter

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Force Propagation of flow of Granular Materials through an Orifice in Start up Stage

Force Propagation of Flow of Granular Materials through an O...

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2012 3rd International Conference on Applied Mechanics and Mechanical Engineering(ICAMME 2012)

作者： Haiping Zhu Boshi Xia Aibing Yu School of Computing Engineering and Mathematics University of Western Sydney School of Materials Science and Engineering The University of New South Wales

In this paper, early stage of granular materials flowing through the orifice of a cuboid hopper with flat bottom is investigated based on the results generated by using the discrete element method. The results show that in the start up stage of the flow, a switch curve is formed between static and flowing particles, and a force arch on which the forces are very small is generated below the switch curve. Both curves propagate into the granular bed with the discharge of particles, and reach the top of the bed when a steady state is achieved.

关键词： Granular mechanics discrete element method particle flow hopper simulation

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