Study on the Water Sensitivity of Secondary Loess and Rainfall Indicators for Shallow Landslides in the Tianshui Region

    Secondary loess is extensively distributed across the northwestern regions of China. Under the impact of extreme rainfall, slopes composed of this material are highly susceptible to failure, frequently resulting in landslides that lead to severe loss of life and property. Geological hazard surveys reveal that landslides in the Tianshui region predominantly occur in secondary loess, with over 70% classified as rainfall-induced shallow landslides. The rapid economic development in Tianshui has been accompanied by insufficient understanding of the physical and mechanical properties of soil layers, limited recognition of the water-sensitive behavior of secondary loess, and inadequate stabilization measures for excavated slopes and soil masses. These factors have collectively undermined the original stability of slopes and intensified the degradation of the geological environment.    This study investigates the influence of water on the strength parameters of secondary loess in the Tianshui region through comprehensive physical and mechanical testing. Simulated rainfall experiments are also conducted to analyze the effects of rainfall intensity and slope gradient on infiltration rates and to establish the relationship between precipitation and soil moisture content. These findings are of critical importance for defining early warning indicators of rainfall-induced shallow landslides in secondary loess deposits in the Tianshui region. The results aim to provide a scientific basis for local governments in preventing geological disasters, protecting the geological environment, and fostering sustainable economic development.