Effects of Dry–Wet Cycling and Temperature on Shear Strength and Microscopic Parameters of Coal Measure Soil

Exposed coal measure soil (CMS) found in the mountains of Southern China is significantly affected by the seasonal climate, which makes this region prone to frequent shallow landslides. In this regard, very few studies have focused on the shear strength and microscopic characteristics of CMS subjected to dry–wet cycling and temperature. The aim of this study was to experimentally investigate the effects of dry–wet cycling and temperature on shear strength and microscopic parameters of CMS. We carried out an unconsolidated undrained triaxial test and scanning electron microscopy of CMS obtained from the K209 slope on the Chang-li highway. Our results indicated that the soil shear strength and microstructure parameters significantly decreased before three dry–wet cycles. Above 35 °C, the temperature affected mainly the mean fractal dimension. The soil cohesion was negatively correlated with the fractal dimension and positively correlated with the probability entropy. The surface-crack occurred once the stress value of high temperature was greater than 0.57 MPa. Strain-softening, swelling–shrinkage, low soil strength, and high soil temperature formed the main factors underlying rainfall-induced K209 shallow landslides.