Study of the effects of clay content on loess slope failure mode and loess strength

The particle size of loess in the Loess Plateau varies from northwest to southeast due to wind direction which is predominantly from the northwest. The clay content of loess is significantly different in the loess area of China resulting in different physical characteristics of loess and loess failure process. To determine the failure process triggered by rainfall, a series of studies were conducted via flume and triaxial tests using loess samples with different clay contents. The effects of clay on water content (WC) change, pore-water pressure (PWP) generation, and the failure process of loess slope were analyzed. The changes in WC and PWP response to the failure process of the slope at different positions were different, and the changes in the shallow layer were found to be more prominent than those at other positions. The changes in WC and PWP gradually decreased with increasing clay content. The clay in loess also plays an important role in the failure process of the loess mass, and the failure process changed from regressive overall failure to erosion-shallow sliding failure and then to erosion failure with increasing clay content. Finally, loess strength with different clay contents was tested and discussed. The strength increased and the M value decreased gradually with increasing clay content. Based on the experimental results, it was concluded that clay in loess has a significant impact on the failure process and strength of the loess mass, and the results of the current study would provide support for loess slope mitigation.