节理峰前剪切刚度软化模型及其影响因素分析

Pre-peak shear constitutive model considering the softening shear stiffness and its influencing factors

节理峰前剪切应力-位移曲线是研究节理剪切行为的重要内容。然而目前对于节理峰前剪切行为大多以线性描述,不能较好的描述非线性的特点。对于非线性的描述也仅仅是唯象描述剪切应力-位移曲线,未能反映影响模型的参数物理意义及影响因素。以峰前节理刚度软化行为为出发点,采用归一化的思想将节理剪切刚度与位移无量纲化,用双曲线函数表示出剪切刚度与位移之间的关系。提出了考虑刚度软化的峰前剪切本构关系,通过与试验结果对比验证了本构关系的合理性。影响该模型最重要的两个因素是初始剪切刚度与峰值剪切位移。以Greenwood和Williamson模型为基础在细观上探讨了初始剪切刚度的影响因素;抓住法向应力与节理粗糙度主要因素,探讨了影响峰值剪切位移的影响因素。对模型参数的研究有助于进一步阐明节理峰前剪切机理。

The shear stress-displacement curve is an important tool in the study of the shear behavior of rock joint.However,at present,most of the shear models characterizing pre-peak shear behavior are linear,which are unable to describe the nonlinear characteristics well.The existing nonlinear description is only the phenomenological description,which fails to reflect the physical meaning and clarify the important parameters affecting the model.Based on the normalized idea,it is convenient to non-dimensionalize the shear stiffness and displacement,and the relationship between the shear stiffness and the displacement is represented by the hyperbolic function.The pre-peak shear constitutive model considering the softening shear stiffness is proposed,and verified by experimental results.The initial shear stiffness and the peak shear displacement are the main factors affecting the pre-peak shear constitutive model.The influencing factors of initial shear stiffness and the peak shear displacement are discussed,which is useful for further clarifying the mechanism of the pre-peak shear behavior.