Model testing of dynamic response of loess to impact load from helicopter landing

To investigate the dynamic behaviour of loess under the impact loads of two tyres attached to a helicopter’s landing gear, a loading device capable of simultaneously applying dual impact loads was designed. A series of physical model tests, varying in impact energy and water content of the loess samples, were conducted. The study explored the settlement pattern, vertical dynamic stress distribution, and the effects of impact energy and water content. Results revealed that settlement in the shallow layer exhibits a characteristic W-shape, while the vertical dynamic stress time curve displays a single peak pulse. Settlement and vertical dynamic stress increase with higher impact energy. Increasing the water content of the loess sample results in greater settlement but lower vertical dynamic stress. For the simulated helicopter, when the tyre impact energy increases from 23.8 to 60.8 kJ, the resultant crater depth in loess with a moisture content of 16% increases from 7.6 to 18.1 cm, an increase of 11.5 cm. The peak vertical dynamic stress at a depth of 10 cm along the centerline of the tamper increases from 590.98 to 1449.4 kPa, more than doubling. These findings are valuable for the design of landing sites and landing gear systems.