Softening rule of Triassic mudstone in an airport of southwest China

The bedrock of a landslide area of an airport in southwest China is mainly carbonaceous mudstone, mixed sandstone and silty mudstone. According to the mudstone’s moistening soften characteristics, we divide the mudstone into two classifications, namely plane samples and fissure samples. By using scanning electron microscopy, X ray diffraction, X ray fluorescence spectrometry, inductively coupled plasma and ion chromatography, combined with the physical and mechanical analysis, we studied the variation law of mineral composition, chemical composition, micro structure and physical and mechanical indexes as well as the saturated time. Finally, the softening process is divided into three stages, the initial softening, continuous softening and stable softening stage.