Dynamic response of dry sands subjected to dual patch impact loads of a wheeled helicopter

Dual patch impact loads are applied through two tires attached to a single landing gear during the landing of wheeled helicopters. To investigate the dynamic response of dry sands under dual patch impact loads from wheeled helicopters, model tests and validated numerical simulations were performed. The findings reveal that the settlement pattern in the shallow sand layer exhibits a characteristic W-shape, with the maximum settlement occurring directly beneath the center of each tamper. The time-history curve of the vertical dynamic pressure along the centerline of each tamper shows a single peak pulse with a duration of approximately 0.01 s. The peak value diminishes with increasing depth. Both the settlement and dynamic vertical soil pressure are dependent on impact energy, increasing as impact energy rises. The center-to-center spacing between the two tampers has a minimal effect on the maximum settlement and peak dynamic soil pressure along the centerline of each tamper. However, it significantly affects the maximum settlement and peak dynamic soil pressure along the centerline between the two tampers. As the spacing increases, the maximum settlement and peak dynamic soil pressure along the centerline between the two tampers decrease due to the attenuation of interaction between the two tampers.