基于DEM方法的不同密度颗粒材料砂堆形成过程的数值研究
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摘要
颗粒堆积是地质工程中较为普遍的现象,而其堆积稳定后的安息角可以在一定程度上反映颗粒堆积的基本特征.用DEM方法研究不同密度分布的颗粒堆积过程及堆积结果,有助于我们在细观层面研究颗粒密度对颗粒堆积结果的影响和验证DEM方法分析颗粒堆积的合理性.本研究用圆形颗粒简化模拟散体颗粒:第一步,用EDEM软件建立相关模型,在模型内生成简化的颗粒,模拟颗粒在重力作用下自由下落和堆积稳定的过程;第二步,模型中生成颗粒下落堆积稳定后,保留模型底部边界,数值模拟研究移除模型上部边界后颗粒散落堆积稳定的过程并测定堆积体的安息角;第三步,对应数值模型,做相关的实验进行对比验证.研究结果表明:在只考虑堆积颗粒密度而忽略其他参数影响的条件下,堆积颗粒材料的密度越小,其堆积稳定后的安息角越大.
Particle accumulation is a common phenomenon in geological engineering, and its stable repose angle can reflect the basic feature of particle accumulation to a certain extent. The DEM method is used to study the accumulation process of particles with different density distributions, which can help us to study the effect of particle density on the particle accumulation results and verify the rationality of particle accumulation simulations by DEM method. This study uses circular particles to simplify the simulation of granular particles. The first step is to establish the relevant model with EDEM software and to generate simplified particles in the model. It simulates the process of free falling and accumulation stability of particles under gravity. In the second step, after the particle falling and accumulation are stabilized, the bottom boundary of the model is retained, and the upper boundary of the model is removed. The repose angle of the accumulation body is then measured. The third step is to conduct relevant experimental tests to compare with the numerical model for verification purpose. The results show that the smaller the density of the deposited granular material is, the larger the resting angle is after the accumulation is stable, when considering the effect of the density of particles and neglecting the influence of other parameters.
Particle accumulation is a common phenomenon in geological engineering, and its stable repose angle can reflect the basic feature of particle accumulation to a certain extent. The DEM method is used to study the accumulation process of particles with different density distributions, which can help us to study the effect of particle density on the particle accumulation results and verify the rationality of particle accumulation simulations by DEM method. This study uses circular particles to simplify the simulation of granular particles. The first step is to establish the relevant model with EDEM software and to generate simplified particles in the model. It simulates the process of free falling and accumulation stability of particles under gravity. In the second step, after the particle falling and accumulation are stabilized, the bottom boundary of the model is retained, and the upper boundary of the model is removed. The repose angle of the accumulation body is then measured. The third step is to conduct relevant experimental tests to compare with the numerical model for verification purpose. The results show that the smaller the density of the deposited granular material is, the larger the resting angle is after the accumulation is stable, when considering the effect of the density of particles and neglecting the influence of other parameters.
引文
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[3]EDWARDS S F,MOUNDFIELD C C.A theoretical model for the stress distribution in granular matter.III.Forces in sandpiles[J].Physica A,1996,226:25-33.
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[9]MEHTA A,BARKER G C.Disorder,memory and avalanches in sandpiles[J].Euro-physics Letters,1994,27:501-506.
[10]CUNDALL P A,STRACK O D L.A discrete numerical model for granular assemblies[J].Geo-technique,1979,29:47-65.
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[12]ZHOU Y C,WRIGHT B D,YANG R Y,et al.Rolling friction in the dynamic simulation of sandpile formation[J].Physica A,1999,269:536-553.
[13]ZHOU Y C,XU B H,YU A B,et al.An experiment and numerical study of the angle of repose of coarse spheres[J].Powder Technology,2002,125:45-54.
[14]李艳洁,徐泳.用离散元模拟颗粒堆积问[J].农机化研究,2005,2:57-59.
[15]LI Y J,XU Y,THORNTON C.A comparison experiments of discrete element simulations and“sand piles”composed of spherical particles[J].Powder Technology,2005,160:219-228.
[16]金鑫,孙刚.基于改进粒子群算法的参数化机翼气动优化[J].力学季刊,2012,33(3):461-468.
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[18]ZHANG D,WHITEN W J.A new calculation method for particle motion in tangential direction in discrete element simulations[J].Powder Technology,1999,102:235-243.