抗转动特性对颗粒材料分散性失稳的影响研究
发布时间：2018-10-22 09:59
【摘要】：对于岩土类的颗粒材料,在特定的应变加载路径下会发生非局部化的失稳现象,此时应力状态处于Mohr-Coulomb屈服面内,试样整体急剧失稳。采用颗粒离散元方法,研究抗转动特性对颗粒材料在等比例应变加载路径下宏、细观力学特性的影响。模拟发现,较为松散的试样更易发生分散性失稳,此时颗粒集合体的应力-应变状态满足Hill材料失稳准则。采用考虑颗粒转动的接触模型进行离散元模拟,通过改变颗粒间接触的转动摩擦系数,从宏观和细观层面分析等比例应变加载路径中颗粒材料的稳定性。颗粒抗转动能力的增强可以降低材料发生分散性失稳的可能性,随着转动摩擦系数的增加,应力路径由应变软化逐渐转为应变硬化,原本会发生分散性失稳的松散颗粒集合体表现出与密实颗粒集合体相似的宏观力学特性;颗粒集合体的内部结构表现出相应的细观作用机制,转动摩擦系数的增加有效地抑制了颗粒转动,虽然降低了颗粒体系的配位数,但增加了颗粒之间的接触力,增强了颗粒体系力链结构的稳定性和各向异性,形成稳定的结构持续抵抗外荷载的施加,从而试样整体不会形成松散的接触状态而失去稳定性。
[Abstract]:For rock and soil granular materials, the unlocalized instability will occur under a specific strain loading path, where the stress state is within the Mohr-Coulomb yield surface, and the whole specimen is rapidly unstable. The effect of anti-rotation properties on the macro and meso-mechanical properties of granular materials under the isometric strain loading path is studied by means of particle discrete element method. It is found that the loose samples are more prone to the dispersion instability, and the stress-strain state of the granular aggregates meets the Hill instability criterion. The contact model considering particle rotation is used to simulate the stability of particle material in the strain loading path from macroscopic and meso levels by changing the rotational friction coefficient of contact between particles. The enhancement of the anti-rotation ability of particles can reduce the possibility of dispersion instability. With the increase of rotational friction coefficient, the stress path gradually changes from strain softening to strain hardening. Loose particle aggregates, which would otherwise have dispersive instability, exhibit macroscopic mechanical properties similar to those of dense particle aggregates, and the internal structures of particle aggregates exhibit a corresponding meso-mechanism. The increase of rotational friction coefficient effectively inhibits the particle rotation. Although the coordination number of the particle system is reduced, the contact force between particles is increased, and the stability and anisotropy of the force chain structure of the particle system are enhanced. A stable structure is formed to resist the application of external loads, so that the whole specimen will not form a loose contact state and lose its stability.
【作者单位】： 武汉大学水资源与水电工程科学国家重点实验室;武汉大学水工岩石力学教育部重点实验室;
【基金】：国家自然科学基金青年基金项目(No.51509190);国家自然科学基金面上项目(51579193) 中国博士后科学基金面上资助(No.2016T90727)~~
【分类号】：TU43
本文编号：2286850
[Abstract]:For rock and soil granular materials, the unlocalized instability will occur under a specific strain loading path, where the stress state is within the Mohr-Coulomb yield surface, and the whole specimen is rapidly unstable. The effect of anti-rotation properties on the macro and meso-mechanical properties of granular materials under the isometric strain loading path is studied by means of particle discrete element method. It is found that the loose samples are more prone to the dispersion instability, and the stress-strain state of the granular aggregates meets the Hill instability criterion. The contact model considering particle rotation is used to simulate the stability of particle material in the strain loading path from macroscopic and meso levels by changing the rotational friction coefficient of contact between particles. The enhancement of the anti-rotation ability of particles can reduce the possibility of dispersion instability. With the increase of rotational friction coefficient, the stress path gradually changes from strain softening to strain hardening. Loose particle aggregates, which would otherwise have dispersive instability, exhibit macroscopic mechanical properties similar to those of dense particle aggregates, and the internal structures of particle aggregates exhibit a corresponding meso-mechanism. The increase of rotational friction coefficient effectively inhibits the particle rotation. Although the coordination number of the particle system is reduced, the contact force between particles is increased, and the stability and anisotropy of the force chain structure of the particle system are enhanced. A stable structure is formed to resist the application of external loads, so that the whole specimen will not form a loose contact state and lose its stability.
【作者单位】： 武汉大学水资源与水电工程科学国家重点实验室;武汉大学水工岩石力学教育部重点实验室;
【基金】：国家自然科学基金青年基金项目(No.51509190);国家自然科学基金面上项目(51579193) 中国博士后科学基金面上资助(No.2016T90727)~~
【分类号】：TU43
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