Calculation Model and Influencing Factors of Surrounding Rock Loosening Pressure for Tunnel in Fold Zone

Figure 6

Relationship between geological tectonic stress F and surrounding rock loosening pressure (q). (a) Class VI surrounding rock zone,  = 7.5°. (b) Class V surrounding rock zone,  = 12.5°. (c) Class IV surrounding rock zone,  = 23°. (d) Class III surrounding rock zone,  = 43°. (e) Class II surrounding rock zone,  = 60°. (f) Class I surrounding rock zone,  = 73°. 1— = 0.2; 2— = 0.4; 3— = 0.6; 4— = 0.8; 5— = 1.0; 6— = 1.2.

(a)

(b)

(c)

(d)

(e)

(f)