Aerodynamic modeling of the Yigong gigantic rock slide-debris avalanche,Tibet, China

On the April 9 of 2000, a gigantic rapid rock slide-debris avalanche occurred in Bomi, Tibet. Some 280–300 × 10⁶ m³ of material travelled 10 km within 10 min and dammed the Yigong River, forming a 2.9 × 10⁹ m3 barrier lake. Wind tunnel testing was undertaken to determine the aerodynamic parameters involved, from the initial rock slide-fall to its point of impact. The paper reports the numerical analyses undertaken and discusses the significance of the air-cushion effect. It is concluded that Yigong rapid rock slide-debris avalanche “flew” in the air for about 12.9 s from its detachment from the source to its collision with the floor of the Zamunong gully at 3,317 m asl. The velocity of the avalanche mass at the point of detachment was some 81.8 m/s and the collision velocity approximately 117 m/s.