A Theoretical Calculation Method of the Unsupported Span for the Shallow Tunnel in the Soft Stratum

Figure 8

Model tests of the tunnel face and the unsupported span [19]. (a) The unsupported span is 2.0 m. (b) The unsupported span is 3.0 m. (c) The unsupported span is 4.5 m. (d) The unsupported span is 5.0 m.

(a)

(b)

(c)

(d)