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颗粒物质的多尺度结构及其研究框架

The multiscale structure of granular matter and its mechanics

  • 摘要: 颗粒物质力学的研究刚刚起步,目前很多方面还不完善.文章作者认为,该学科是应用性很强的基础学科,因此提出了从实际应用中去发现科学问题,进而促进颗粒物质力学基础理论发展的研究思路,并以土力学为例做了说明.土是岩石经风化作用,由重力、流水和风力等搬运和沉积而成的产物,是密集颗粒物质体系之一.土粒是构成土体骨架、传递载荷的基本单元,与颗粒间复杂分布的孔隙水、气体共同决定了土体的非线性本构关系、剪胀(剪缩)和应力路径相关等复杂特征.以研究密集分布颗粒体系的颗粒物质力学在近20年内得到充分发展,它侧重现象的机理分析和实验的精细检测,为土力学的基础研究提供了重要启示.基于文章作者多年土力学和颗粒物质力学的研究经验,提出了土体具有多尺度结构的观点:除微观的单颗粒尺度和宏观土体尺度外,细观尺度的力链是颗粒接触力传递的路径,是存在于土体内的相对稳定的结构体.建立了初步的理论研究框架,提出了力链网络的复杂动力学响应决定土体复杂本构关系的基本设想.下一阶段将从理论分析、物理试验和基于自主开发的颗粒离散元模拟3个方面进行研究,逐渐充实土力学多尺度理论体系,以期取得突破.

     

    Abstract: Soil is the naturally occurring, unconsolidated or loose covering of broken rock particles, which consists of densely packed solid particles, interstitial liquid and gas. This collection of particles forms a supporting skeleton and determines the ability of soil to resist shear stress, as described in the concept of effective stress proposed by Karl Terzaghi. Many efforts have been made to apply this concept in engineering problems, rather than conducting more fundamental investigations on the geometrical and mechanical properties of the soil skeleton. In the past two decades, the closely related discipline of granular matter mechanics has received much attention due to its various intriguing phenomena. Many fundamental studies have provided a deeper understanding of granular matter. Based on our research on soil mechanics and granular matter in the last ten years, we propose that soil is intrinsically multiscale, i.e. besides microscale primary particles and macroscale bulk matter it also consists of mesoscale force chains. The correlations among the different scales are crucial. The mesoscale force chain network is determined both by particle properties and macroscopic boundary conditions. The evolution of the force chain network contributes to the macroscopic mechanical properties of soil.

     

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