Effect of collapse-type lateral pressure induced by irrigation on loess landslide

Loess collapse-type lateral pressure may have landslide-promoting effect in loess slope areas. A study on the variability of loess collapse-type lateral pressure in Heifangtai area and its sliding mechanism has been analyzed. Collapse tests and numerical simulations were conducted according to local safety field theory. The results indicate that Heifangtai loess is self-weighted collapsible loess. As the depth or moisture content increases, the lateral pressure gradually increases, correspondingly the deformation becomes greater. In saturated state, the maximum lateral pressure reaches 123kPa, the lateral pressure coefficient increases of up to 1.4 times. As the water content increases from 4% to 20%, the total slope displacement is predominantly horizontal, increasing from 12mm to 140mm, the lateral pressure coefficient gradually increases, and the increase range gradually expands; the failure area becomes gradually wider until the slope toe is penetrated. Collapse action leads to tensile stresses in the upper part of the slope, making it prone to collapse-type crack formation, resulting in dominant channels of surface water infiltration and forming landslide scarps. What's more, collapse action also enables the formation of compressive stresses in the lower part of the slope, resulting in outward extrusion of deep soil, increased sliding force, and landslide formation.