宝兰客专兰州段泥岩软化特性的微观研究

Microscopic Study on Softening Characteristics of Mudstone in Lanzhou Section of Baoji-Lanzhou Dedicated Passenger Railway Line

针对西北地区广为分布的黄土地层泥岩,结合宝兰客专上庄隧道工程,通过X射线衍射、扫描电子显微镜以及岩石的物理水理性质试验等手段测定该泥岩地球化学成分、微观构造、矿物成分和物理水理性质,研究黄土地层泥岩软化过程中的变化规律。研究表明,该泥岩中金属元素的含量较多,导致泥岩的颜色较深,且其中矿物成分主要为石英、方解石及斜长石,占总矿物含量的77%,而蒙脱石含量为0,仅含有少许伊利石和高岭石;天然状态下泥岩含有较多的黏土颗粒,这些黏土颗粒间主要是面对面接触或点对面接触,在水的作用下,颗粒间的连接逐渐被破坏,导致岩石内部构造损坏,使得泥岩产生软化现象;化学成分及室内试验结果均表明,该泥岩几乎没有膨胀性,但是具有一定的崩解性。

Aiming at northwest widely distributed loess mudstone,this paper determines the geochemical composition,microstructure,mineral composition and physical and water properties of the mudstone and studies the dynamic change law of softening of mudstone in loess strata by means of X-ray diffraction,scanning of electron microscopy and physical properties test of rock based on Shangzhuang Tunnel project on Baoji-Lanzhou dedicated passenger line. The study results show that the high content of metal in the mudstone leads to darker color of the mudstone, the components are mainly quartz, calcite and plagioclase,accounting for 77% of the total minerals without montmorillonite and with only a small amount of illite and kaolinite. The mudstone under natural condition contains more clay particles,which are mainly in face-to-face or point-to-face contact. Under the action of water,the connection between the particles is gradually destroyed,resulting in damage of the rock internal structure and softening of the mudstone. Chemical composition and indoor test results show that the mudstone is almost of no expansion,but with a certain degree of disintegration.