泥岩耐崩解性与矿物组成相关性的试验研究

Experimental investigations on correlation with slake durability and mineral composition of mudstone

岩石的耐崩解性是岩土工程实践中岩体和岩石材料的重要特征参数之一。基于4组不同成煤期煤系地层泥岩的耐崩解性对比试验,结合岩样的X射线衍射(XRD)和压汞试验(MIP)分析结果,研究了循环崩解作用下泥岩崩解物形态特征和耐崩解性指数的变化规律,并探讨了泥岩耐崩解性差异、差异产生机理及其与矿物组成的关系。研究结果表明:泥岩的耐崩解性与其矿物组成和孔裂隙结构特征密切相关;随崩解循环次数的增多,泥岩耐崩解性指数呈负指数关系递减;受矿物组成的影响,泥岩崩解机理可分为两类:矿物组成中含有蒙脱石的,崩解主要由岩体遇水时内部差异膨胀引起;矿物组成中不含蒙脱石的,崩解主要由岩体遇水时内部孔裂隙相界面受水的楔裂压力作用,孔裂隙扩容引起。

Slake durability of rocks is an important property of rock-mass and rock-material in geotechnical practice.Based on the slake durability comparison test of four groups mudstone from the coal measure strata of different coalforming periods,and by combining the results of X-ray diffraction( XRD) and mercury injection test( MIP),the variation of shape and size of slaking pieces and slake durability index of mudstone under cycles slaking were studied. The difference of mudstone slake durability,its mechanism and its relationship with mineral composition were discussed.The research results are as follows: the slake durability of mudstone is closely related to their mineral composition and pore-fracture characteristics. The decrease of mudstone slake durability index follows a negative exponent relationship with the increase of slaking cycle times. The slaking mechanism of mudstone can be divided into two classes. When the mineral composition of rock contains montmorillonite,the rock slaking is resulted from block swelling difference caused by montmorillonite expansion in water. When the mineral composition of rock does not contain montmorillonite,the rock slaking is resulted from inner pore-fracture expansion caused by tension from water squeezing air in pore-fracture.