武陵山湘西北地区细碎屑岩崩解性及其微观特征研究

Study on the Disintegration and Micro Characteristics of Microclastic Rocks in Northwest Hunan,Wuling Mountain

武陵山湘西北地区泥质粉砂岩、粉砂质泥岩等细碎屑岩类地层滑坡发育较密集,为该区重要的易滑地层。为探索细碎屑岩崩解特性及其微观特征,通过室内耐崩解试验,分析其耐崩解指数、崩解物成分、崩解产物颗粒形态,并对崩解机理进行了探讨。研究结果表明:武陵山湘西北地区细碎屑岩的崩解性较强,且泥质含量越高,崩解能力越强;崩解过程中,岩石颗粒矿物含量持续增大,而黏土矿物则表现出较稳定的持续下降,颗粒整体形态由扁平、棱角状表面向等轴、圆形表面转变。从崩解的微观机制上分析,细碎屑岩的崩解能力主要受其矿物成分及微观结构影响:含亲水性黏土矿物较多时,遇水后黏土矿物的水化作用以及膨胀作用导致了崩解的产生;黏土矿物较少时,颗粒表面的楔裂压力促使裂隙向纵深发展,最终使裂隙贯通。

The landslides of microclastic rocks strata such as muddy siltstone and silty mudstone in the Northwest Hunan area of Wuling Mountain are densely developed and are important slippery strata in this area.In order to explore the disintegration characteristics and microscopic characteristics of microclastic rock,the disintegration resistance index,the composition of disintegration products,and the particle shape of disintegration products of microclastic rock are analyzed through laboratory disintegration resistance test,and then the disintegration mechanism is discussed.The results show that the disintegration of the microclastic rocks in the northwest of Hunan area is strong,and the higher the argillaceous content is,the stronger the disintegration ability is.During the disintegration process,the content of the rock particle minerals continue to increase,while the clay minerals show relatively stable continuous decline,and the particles surface is firstly flat and angular and then equidimensional and circular.As far as the micro mechanism of disintegration is concerned,the disintegration ability of microclastic rock is mainly affected by its mineral composition and microstructure.When there are more hydrophilic clay minerals,the hydration and expansion of clay minerals lead to disintegration,and when there are fewer clay minerals,the wedge fracture pressure on the particle surface promotes the fracture to develop in-depth and finally makes the fracture link together.