###### Abstract  
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 \({}^{\circ}\)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. coal measure soil; dry-wet cycles; shear strength; temperature; shallow landslides +
Footnote †: journal: Applied  
**Citation**: [PERSON]; [PERSON] Effects of Dry-Wet Cycling and Temperature on Shear Strength and Microscopic Parameters of Coal Measure Soil. _Appl. Sci._**2023**, 13, 336. [[https://doi.org/10.3390/app13010336](https://doi.org/10.3390/app13010336)]([https://doi.org/10.3390/app13010336](https://doi.org/10.3390/app13010336))
expound the inducing factors and deformation mechanism. Along these research lines, the discrete element method (DEM) is used to perform 3D numerical simulations of the triaxial shear test for CMS [5]. [PERSON] [6] analyzed the effects of the particle shape and size on the physical and mechanical characteristics of soil mass via numerical triaxial-test simulations. [PERSON] [7] researched the variation pattern and stress distribution characteristics of moisture content in rainfall for C-M-S slopes. Here, we note that all these studies focus on the C-M-S physical and mechanical properties of CMS under different water contents. However, very few studies have examined the C-M-S strength behavior under dry-wet cycling. Notably, dry-wet cycling is a familiar shallow-soil weathering degree determined by short-term rainfall and sun exposure. The soil strength characteristics and microstructural features affected by dry-wet cycling have received widespread attention. Moreover, surface-crack occurrence and development in rock soil are generally related to dry-wet cycling [8; 9]. Furthermore, dry-wet cycling is a crucial reason underlying the deterioration of microstructure and macro mechanics of a wide range of unsaturated soils, such as expansive soil [10; 11], loess [12], and red clay [13; 14]. In recent years, researchers have also studied the C-M-S strength characteristics subjected to dry-wet cycling [15; 16]. In this regard, [PERSON] [17] studied the variability in the soil-water characteristic curve (SWCC) of CMS under dry-wet cycling. [PERSON] [18] proved that the suction had a positive effect on the shear strength. [PERSON] [19] analyzed the adsorption strength and shear strength between soil particles affected by matric suction. Here, we note that C-M-S research has mainly been confined to study the effects of dry-wet cycling on soil strength at normal temperature. However, most previous studies have not accounted for summer temperatures that can generate enhanced cracks in rock soil. Moreover, the combined effects of different temperatures and dry-wet cycling on the C-M-S strength have been ignored. As regards general studies on the effects of temperature on soil strength, some theories and methods have been proposed.