基于黏弹性接触的颗粒材料蠕变特性研究

强黏结土体或胶凝砂砾石料等颗粒材料的颗粒间存在较大黏结力，在低应力情况下主要由颗粒接触特性决定颗粒材料的宏观蠕变特性。基于颗粒细观力学方法，研究了二维各向同性颗粒材料的蠕变特性。首先引入速率相关的力与位移关系描述颗粒材料细观颗粒间特性。其次，运用Laplace变换，将时间域内的线黏弹性颗粒材料细观均匀化问题转化为拉氏空间内线弹性颗粒材料细观均匀化问题，随后基于颗粒材料线弹性问题在Reuss、Voigt和一般位移场三种假设下的解，通过Laplace逆变换得到颗粒材料相应的宏观蠕变特性解析模型，并建立了材料蠕变特性的上下限。最后，通过理论模型的解析解与商业软件（PFC2D）的数值结果的对比，验证了理论模型的合理性。

Creep property of granular materials based on viscoelastic interface between micro structural granular

For some of granular materials with large cohesive force, such as strong bond soil or cementitious sand and gravel and so on, their macroscopic creep behavior is mainly dependent on the properties of particle contact under low stress conditions. This paper aims at proposing a two-dimensional isotropic creep property of granular materials through the granular micromechanical approach. To achieve this objective, firstly an appropriate rate-dependent force-displacement relationship is introduced to describe the discrete inter-granular properties of granular materials. Secondly, with help of the Laplace transform, the solution for overall behavior of granular materials in the framework of linearly elasticity can be directly used for the solution of the associated linearly viscoelastic problem in the Laplace space; and then, the main problem is to accurately produce the inverse Laplace transform in the time domain. Thirdly, by taking respectively Reuss static, and Voigt and general kinematic localization assumptions, we obtain analytically the corresponding overall creep behavior of granular materials. Further, the upper and lower bounds of overall creep property are established. Finally, the obtained results compared with the numerical simulation by PFC2D are provided to illustrate their validation.