三维离散元法解析砂型泥石流细观运动特征研究

发布时间：2018-04-23 02:13

本文选题：三维离散元方法 + 泥石流　；参考：《地下空间与工程学报》2017年05期

【摘要】：基于散体介质理论的三维离散元数值分析方法,引入粘滞阻尼模型考虑系统耗能效应,求解固体作用力和流体连续性方程,充分考虑流固耦合作用,对中、细标准砂泥石流过程进行仿真分析,得到不同砂型泥石流破坏过程及渗流场、颗粒速度场、孔隙率、颗粒接触数等参数变化规律。分析表明,中砂、细砂分别表现出分层渐进式和流滑型的破坏模式,这与已有物理试验现象吻合,验证该模型的适用性,并从渗流场分布规律深刻解释该现象发生机理。泥石流过程中土颗粒速度矢量变化规律从细观上揭示了隐藏在颗粒内部的相互碰撞、摩擦、滑动等复杂运动特点,从宏观上揭示了中砂土坡脚薄弱位置率先突破,主滑动体形成直至完全失稳的分级渐进式破坏过程。进一步分析了土体孔隙率和平均接触数分布云图变化规律,中砂泥石流过程中随颗粒运动,滑动体孔隙率逐渐增大,颗粒接触数逐渐减小,并且这种发展趋势逐渐往坡后方土体蔓延;进一步揭示了中砂泥石流分级渐进破坏过程与颗粒速度场分析规律一致。分析结果表明了该模型方法在模拟泥石流这种大变形、流固耦合问题上的适用性,这对泥石流复杂机理的更深入探索是有益的。
[Abstract]:Based on the theory of granular medium, the three-dimensional discrete element numerical analysis method is used. The viscous damping model is introduced to consider the energy dissipation effect of the system, and the equations of solid force and fluid continuity are solved, and the fluid-solid coupling is fully considered. The process of fine standard sand debris flow is simulated and analyzed, and the variation rules of parameters such as the failure process and seepage field, particle velocity field, porosity and particle contact number of debris flow in different sand molds are obtained. The analysis shows that the medium sand and fine sand show the failure modes of progressive stratification and flow slip respectively, which agree with the existing physical experiment phenomenon, and verify the applicability of the model, and explain the occurrence mechanism of the phenomenon from the seepage field distribution law. In the process of debris flow, the variation law of velocity vector of soil particles reveals the complex movement characteristics of collision, friction, sliding and so on, and the weak position of the foot of the middle sand slope is the first to break through macroscopically. The progressive failure process of the main sliding body until it is completely unstable. The distribution of porosity and average contact number of soil mass is further analyzed. The porosity of sliding body increases gradually and the contact number of particles decreases with the movement of particles in the process of middle sand debris flow. This trend of development gradually spreads to the soil behind the slope, which further reveals that the progressive failure process of middle sand debris flow is consistent with the law of particle velocity field analysis. The results show that the model method is suitable for simulating the large deformation and fluid-solid coupling of debris flow, which is beneficial to the further exploration of the complex mechanism of debris flow.
【作者单位】：福建工程学院土木学院;地下工程福建省高校重点实验室;福建省土木工程新技术与信息化重点实验室;同济大学地下建筑与工程系;
【基金】：国家自然科学基金(41272296,51504070,51508099) 福建工程学院校科研启动基金(GY-Z14069) 福建省自然科学基金项目(2016J01205)
【分类号】：P642.23

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