Prediction of the Required Supporting Pressure for a Shallow Tunnel in Layered Rock Strata Based on 2D and 3D Upper Bound Limit Analysis

Figure 6

Change laws of the failure surface under varying parameters. (a) Thickness of the upper and lower layers; (b) tunnel span; (c) parameter A; (d) parameter B; (e) rock compressive strength; (f) rock unit weight.

(a)

(b)

(c)

(d)

(e)

(f)