Taking one shallow-buried air-raid shelter of which buried-depth is about 6m to 13 m for example

this paper simulates the failure laws and the failure mechanism of the tunnel-roof which has different spans and rock characters and different loads using the FLAC; determines the failure fields of the roof rock masses of the tunnel; and then studies the sensitive rock mass of the arch. The results show that the tunnel roof has some bearing capacity when the span is 2 m and the roof-rock is mudstone; and the tunnel collapsed until the load reached 0.7 MPa; but if the span is 3 m

the tunnel collapsed when the load reached 0.33 MPa. If the tunnel roof is pebble stratum

the tunnel collapsed under the overburden pressure even it has no loading. This study has practical meanings to the similar study about the stability of the surrounding rock masses of shallow-buried underground engineering.