塑性强化材料颗粒的微观接触摩擦研究

合理的颗粒接触摩擦模型是从微观角度研究各类结构面强度的基础,然而受制于岩土体颗粒在微观高应力环境中表现出的复杂接触特征,该问题一直未能很好解决。Fujimoto 在2000 年给出了受切向荷载作用的微凸体在理想弹性或完全塑性接触状态下的微观位移特性,但却缺少对塑性强化接触状态下的摩擦进行解析,难被用于分析微观高应力状态下岩土颗粒的接触摩擦。为此,以Fujimoto模型为基础,结合作者曾经提出的塑性强化接触变形理论,在构建塑性强化接触状态下颗粒微观位移模型的基础上,系统的研究了切向荷载作用下塑性强化材料颗粒的接触摩擦机理,阐明了不同接触状态下塑性强化材料颗粒的切向微观位移特征。最后通过算例分析显示了模型的合理性。结果表明:颗粒摩擦本质上是不同法向荷载不同接触状态区域按照不同摩擦类型提供摩擦的综合,而摩擦失稳就是接触面上微滑区扩大、粘着区缩小并消失的过程。

STUDY ON MICRO CONTACT FRICTION OF PLASTIC HARDENING PARTICLES

As the foundation of the microcosmic study on shear strength of structural planes,the contact friction model of particles has never been built rationally because of the complex plastic deformation under high stress.Although the character of asperity micro-displacements caused by a tangential load under perfect elastic or fully plastic contact states was studied clearly by Fujimoto in 2000,it cannot be used to explain the friction mechanism of geotechnical particles with plastic hardening deformations.Here taken the Fujimoto model as the foundation,and based on the plastic hardening contact theory ever proposed by the author,the contact friction mechanism of plastic hardening particles is researched systematically so as to illustrate the relation between friction and tangential displacements with different contact states.At last,an example is given to verify the application of the theoretical method proposed.The result shows that the friction of micro-asperities is the sum of different kinds of friction on different contact areas with different contact states,and the start of sliding is a process that a micro-slip area increases while stick zone disappears.