非均匀散粒体自组织临界性机制初探

MECHANISM OF SELF-ORGANIZED CRITICALITY IN NON-HOMOGENOUS GRANULAR MIXTURES

通过干燥沙石散粒体临界态沙坡实验,证实了沙石颗粒组成的非均匀系数是影响散粒体坡面崩塌自组织临界性的重要因素。利用大型粗颗粒实验系统,进行了不同非均匀系统散粒体沙石相对密度和直剪测试,以此对散粒体自组织临界性的形成条件和机制进行了初步分析。根据随着颗粒非均匀程度增大,堆积体的颗粒堆积结构渐趋复杂,颗粒间运动摩擦阻力增大的实验现象,提出观点非均匀散粒体系统的物理力学性质具有失稳状态多样性和能量耗散加剧的特点,使扰动-反馈的放大作用被抑制,从而能够保持整体结构稳定,因此,大尺度的系统也可以呈现自组织临界性现象。

Based on the experiment of critical slope made up of dry sand-gravel mixtures,it is confirmed that self-organized criticality(SOC) in granular mixtures is strongly influenced by non-homogeneity of granular material. Using large-scale coarse grained soil test system,the relative density and direct shear characteristics of sand-gravel mixtures in different size distribution are tested. The occurring condition of SOC and its mechanism are discussed. It is observed that,along with the increment of non-homogeneity,the piled structure becomes more complex,and the sliding resistance among sands grows accordingly. Furthermore,it is concluded from experiments that if the physical characters determined by structure of non-homogenous granular mixtures,the multiform failure states and higher energy dissipation can cause sufficient restraint on disturbing-feedback propagation,granular mixtures will maintain overall stabilization. As a result,a large-scale system can present the SOC as well.