Abstract: The failure process and failure modes of shallowcovered and asymmetricallyloaded singletube tunnels or shallowcovered and asymmetricallyloaded tunnels with small net spacing are studied by means of selfdeveloped tunnel model testing facilities. The study results show that the failure of shallowcovered and asymmetricallyloaded tunnels can be regarded as the collapse failure under the action of gravity, the scale and scope of the failure depend on the asymmetrical loading angle of the shallowcovered and asymmetricallyloaded tunnel and depend on the mechanical parameters of the rock mass, with the scope of the failure mainly depending on the asymmetrical loading angle.

Key words: asymmetricallyloaded tunnel under shallow cover, progressive failure, model test