红层软岩微观结构与抗剪强度关系实验分析

红层软岩属于滑坡、崩塌灾害的易发地层,岩石的微观结构特性对其宏观力学强度有着重要影响。对四川省屏山县和云南省绥江县采集的侏罗系红层砂岩、粉砂岩和泥岩样品进行了扫描电镜观察及变角模抗剪强度实验。基于MATLAB数字图像处理技术,提取了红层砂岩、粉砂岩和泥岩的微观结构参量,即孔隙率、颗粒磨圆度、颗粒定向度及欧拉数的量化值,进一步分析了上述各参量和抗剪强度的定量关系。研究结果表明:红层软岩的抗剪强度和孔隙率呈负指数关系,和颗粒磨圆度、定向度呈负相关线性关系,和欧拉数呈正相关线性关系。

Preliminary Research on the Relationship Between Microscopic Structure and Shear Strength of Red-bed Soft Rocks

Red-bed soft rocks belong to the layers which are susceptible to landslide and collapse.The micro-structural characteristics of the rock have an important impact on its macroscopic mechanical strength.In this paper,the micro-structural observation with scanning electron microscopy(SEM) and the angle-changed shear strength test of the Jurassic red-bed sandstone,siltstone and mudstone samples which were collected from Pingshan County in Sichuan Province and Suijiang County in Yunnan Province were conducted.A large number of microstructures of red-bed sandstone,siltstone and mudstone were analyzed and the shear strength values of the red-bed soft rocks were obtained.The microstructure parameters,i.e.porosity,particle roundness,particle orientation and the quantized value of Euler number of the red-bed sandstone,siltstone and mudstone were extracted based on MATLAB digital image processing techniques.Then the quantitative relationship between the above parameters and the shear strength were analyzed.The results show that the shear strength and porosity of the red-bed soft rock have a negative exponential relationship;the shear strength and particle roundness and particle orientation have a negative linear relationship;the shear strength and the Euler number have positively correlated linear relationship.