中文摘要：

颗粒物质是具有复杂力链网络的常见体系,其平衡和稳定性取决于内部力链骨架的几何结构和力学性能。为恰当刻画颗粒体系的微细观力学行为,从颗粒局部排列形态、颗粒间接触力和颗粒及外荷载的物理参数出发,展开基于二维数字图像相关技术（2D-DIC）的集中力作用下颗粒体系变形的试验。通过结合DIC的试验方法,应用牛顿力学理论及颗粒线性动量平衡获得颗粒间接触力的大小和方向,确定力链的动力学规律;得到颗粒间接触力大小分布变化并提取颗粒体系力链：提出颗粒排布的两种状态：横向传力和纵向传力状态;分析颗粒接触面法线与水平轴的夹角α、传力角β,讨论了α、β对力链断裂破坏的影响;分析颗粒直径d与外荷载压条直径D的比值R以及压条下表面能直接接触的最大颗粒数N等参数,为描述力链的演化和破坏重构机制提供参考基础;简单阐述了力链网络在外荷载下的微细观统计效应对体系宏观力学性质的影响规律。

英文摘要：

A particle system has a complex force chain network,and its balance and stability depend on the geometrical structure and mechanical properties of the internal force-chain framework.To depict the micro-mesoscopic mechanical behavior of the particle system,we start with specifying the local arrangement morphology of particles,the contact force between particles and the physical parameters of particles and external load,and then conduct the deformation tests on the particle system subjected to a concentrated force based on the two dimensional-digital image correlation（2D-DIC）.With combining with the DIC test method,the Newtonian mechanics theory and the particle linear momentum balance are used to obtain the contact force and the direction of contact force between the particles,and then determine the kinetics of the force chain.Once the distribution and variation of contact force between the particles are obtained,the force chain is demonstrated.It is suggested that there are two states in particle system,namely,the transverse force transmission state and the longitudinal force transmission state.The parameters such as the angle α between the normal of the contact surface of particles and the horizontal axis,the force transmission angle β are analyzed.The influences of α andβ on the force chain damage are discussed.The parameters,the ratio R of the particle diameter d to the external load diameter D and the maximum number N of particles contacted with the loading rod,are analyzed.All of the above can provide a guideline for describing the evolution,destruction and reconstruction mechanism of the force chain.