基于摩擦滑动的低应力区岩石变形记忆性机理

Mechanism of rock deformation memory effect in low stress region based on frictional sliding

采用砂岩试样进行岩石记忆性物理实验,描述岩石变形记忆性的基本特征。在物理实验及力学基本原理的基础上,提出在低于微裂纹初始应力以下应力区,变形记忆性的机理为微裂纹和颗粒接触面的摩擦滑动。基于此机理,构建包含Hook体和圣韦南体的基本单元模型,用来模拟单微裂纹或颗粒接触面上的摩擦滑动,对基本单元进行分析。将基本单元组合构建含多接触面的理论模型,对含大量微裂纹及颗粒的岩石进行模拟。研究结果表明:岩石变形记忆性存在于低应力区域;力学模型中的应变差曲线特性与实验曲线特性相吻合,可产生变形记忆性,由此证明微裂纹及颗粒接触面的摩擦滑动可以产生岩石变形记忆性。

The physical experiment was performed on the sandstone sample.The experiment gave the basic features of the deformation memory effect.Based on the experiment and basic mechanics,the frictional sliding over pre-existing crack interfaces and grain boundaries was proposed as the mechanism for the deformation memory effect in the low stress region.A basic model that consists of Hook body and St.Venant body in one dimension for simplification was constructed and then a model with many basic elements was developed to simulate the rock specimen with a large number of crack interfaces and the grain boundaries.The results show that the rock memory effect exists in the stress region,and the characteristics of the differential strain curve in the model is in accordance with that in the experiments.From above,the frictional sliding over the cracks interfaces and grain boundaries can produce the rock deformation memory effect in the low stress region.