Numerical investigation on failure mechanism of tunnel lining with different fault dip angles and Geological Strength Index under geohazard of fault movement and seismic action

Figures & data

Figure 1. Validation—Peak strain variation for different dip angles.

Figure 2. Flowchart for methodology adopted.

Table 1. Properties of materials.

Parameter	Phyllitic quartzite (footwall and hanging wall)	Migmatic gneiss (fault zone)	Grouting	Tunnel lining
Material model	Mohr Coloumb	Hoek-Brown	Linear elastic	Elastic
Drainage type	Non porous	Non porous	Non porous	Non porous
Unsaturated unit weight (kN/m^3)	26.28	26.28	24	25
Saturated unit weight (kN/m^3)	26.38	26.38
Young’s modulus (kN/m^2)	15.05 x 10^6	Varies based on GSI	21.50 x 10^6	32 x 10^6
Poison’s ratio	0.24	0.24	0.2	0.2
Cohesion (kN/m^2)	3000	3000	–	–
Friction angle	38.88	38.88	–	–
Interface strength	Rigid	Manual	Rigid	–
Thickness (m)	–	–	0.25	0.40

Figure 3. Numerical model for (a) 30° dip angle, (b) 90° dip angle, and (c) 2D representation of fault movement.

Table 2. Hoek-Brown parameters.

Dip angle (degree)	GSI	S	a	Uniaxial compressive strength of rock mass σc (kN/m^2)	Youngs modulus of rock mass (kN/m^2)
90/75/60/45/30	80	0.1084	0.5006	15250	13.250 x 10^6
	60	0.01174	0.5028	4950	7.826 x 10^6
	40	0.001273	0.5114	1530	2.400 x 10^6
	20	0.0001379	0.5438	369	0.6873 x 10^6

Figure 4. (a) Time history graphs of selected ground motions and (b) displacement Vs time graph for selected ground motions up to 20 sec.

Figure 5. Arias intensity graphs of selected ground motions.

Table 3. Ground motion details.

Earthquake event name	Station name	Fault distance (km)	Component (degree)	Magnitude Mw	Shear wave velocity Vs (m/s)
Kobe, Japan (1995)	Kobe University	0.9	90	6.9	1043
Loma Prieta, USA (1989)	Gilroy Array #1	8.84	90	6.93	1428.14
Kocaeli, Turkey (1999)	Gebze	10.92	0	7.51	792
Northridge, USA (1994)	LA - Wonderland Ave	20.29	185	6.69	1222.52

Figure 6. Bending moment variation along the length of the tunnel for (a) 30° dip, (b) 60° dip, and (c) 90° dip at tunnel crown.

Figure 7. Bending moment variation along the length of the tunnel for (a) 20 GSI and (b) 80 GSI at tunnel crown.

Figure 8. Axial force variation along the length of the tunnel for (a) 30° dip, (b) 60° dip, and (c) 90° dip at tunnel crown.

Figure 9. Axial force variation along the length of the tunnel for (a) 20 GSI and (b) 80 GSI at tunnel crown.

Figure 10. Deformation in tunnel lining for (a) 30° dip angle and (b) 80 GSI.

Figure 11. Bending moment variation along the tunnel circumference for (a) 20 GSI and (b) 80 GSI at 95 m from tunnel portal.

Figure 12. Bending moment variation along the tunnel circumference for (a) 20 GSI and (b) 80 GSI at 105 m from tunnel portal.

Figure 13. Bending moment variation vs dynamic time at left side of tunnel at (a) 95 m and (b) 105 m from tunnel portal.

Figure 14. Axial force variation vs dynamic time at left side of tunnel at (a) 95 m and (b) 105 m from tunnel portal.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article.