Effect of Dry-Wet Cycling on the Residual Strength Characteristics of Coal Measure Soil

Abstract

Coal measure soils are the main component in the slip zones of landslides along the Changli highway in China. Therefore, exploring the residual strength of coal measure soil affected by dry-wet cycling is helpful for evaluating landslides. However, very few researchers have reported on the residual strength behavior of coal measure soil subjected to dry-wet cycling. In this study, we performed three tests (ring shear test, scanning electron microscopy test, and mercury intrusion porosimetry test) to evaluate the residual strength behavior of coal measure soil under different dry-wet cycles. Our results indicated that the peak strength decreased with increasing dry-wet numbers and that dry-wet cycling had no evident effect on the residual strength. Moreover, the residual strength in the slip soil was approximately proportional to the normal stress. Furthermore, the degeneration of peak cohesion exponentially increased, and the porosity and fractal diameter also increased with the dry-wet numbers. The connection between mineral particles changed from a stable layered structure to an unstable chain structure. Consequently, we inferred the failure mechanism of K213-type shallow landslides and formulated appropriate preventive measures. This study is of great significance for understanding the mechanical behavior of the slip zone of coal measure soil and predicting the re-emergence of coal measure soil landslides.