Identification and Treatment of Collapse and Mud Inrush Caused by Deep Karst Trough in Tunnels

Table 2

Revealed karst caves before mud inrush and collapse.

Serial no.	Chainage	Location	Size of the karst caves	Filling status
1	GK0+398	Left side of tunnel face	The karst fissure developed along the longitudinal direction of the tunnel at 15°, with a width of about 2 m, a height of 17 m, and a length of 16 m.	Wet inside the cavity, without fissure water, filled with mud
2	GK0+400	Right side of tunnel face	The karst cave is 3.6 m long and 4 m wide upward along the tunnel, and the vertical height above the vault is 7.5 m.	Wet inside the cavity, without fissure water, filled with mud
3	GK0+405	The right sidewall	The karst cave extends downward, with a diameter of 3.5 m and a visible depth of about 6.5 m.	No filling