Study on failure of red clay slopes with different gradients under dry and wet cycles

In order to deeply study the failure mechanism of red clay slope engineering under the influence of gradients and natural environment, Guizhou red clay was chosen as the research object and two slope models with different gradients were established respectively. The indoor dry-wet cycle test of the red clay slope was conducted. With the finite element software, this study examined the evolution of slope displacement, moisture content, and pore water pressure with time at different angles. It also analyzed the failure modes of slopes at different angles. The results showed that: (1) the forms of slope failure were mainly splashing, surface erosion and gully, and the slope failure was caused by the combination of rainwater infiltration and runoff erosion; (2) under the same climatic conditions, when the slope became steeper, the influence of rain infiltration and sunshine was greater. Besides, there was an increase in the overall value of the moisture content, pore water pressure, and amplitude of variation. Furthermore, the internal soil strength decreased, while the horizontal displacement accelerated exponentially; and (3) no obvious sliding surface was found during the test. The displacement increased from the crest of the slope to the toe of the slope. The collapse began to occur from the toe of the slope, and the coalescence of multiple disintegrations caused the landslide.