Limit Analysis of Collapse Mechanisms for Tunnel Roofs Subjected to Pore Water Pressure: A Numerical Approach

Table 6

Dimensions of collapsing block varied with tunnel radius r.

r	H (m)	L (m)	P (kN/m)
3.75	0.2960	0.4236	3.81
5.00	1.2822	1.6050	60.63
6.25	2.4070	2.9206	201.98
7.50	3.6527	4.4024	449.33

Note: H, L, and P represent the height, width, and weight per unit length of collapsing block, respectively. The parameters are A = 0.35, B = 5/6, σ_c = 3 × 10⁴ kPa, σ_t = σ_c/100 = 300 kPa,  − h_t = 16.68 m, C = 50 m, andγ_sat = 28.33 kN/m³.