Application of the Upper-Bench CD Method in Super Large-Span and Shallow Tunnel: A Case Study of Letuan Tunnel

Table 6

Statistics of maximum principal stresses for different construction methods.

Construction method	Maximum tensile stress (MPa)	Maximum compressive stress (MPa)
Upper-bench CD method	0.109	0.119
CD method	0.201	0.15
CRD method	0.177	0.179
Both-side drift method	0.176	0.166