Research and Application of Support Resistant Limiting Dampers in the Deep-Buried Large-Section Loess Tunnel

Table 5

Safety comparison table.

Scheme	Mileage	Cracked or not	Cause of cracking	Structural safety
I	DK390 + 786∼DK390 + 520	Along the longitudinal direction of the tunnel, a continuous crack and dislocation of about 180 m occurred on the left and right arch waist	On the action of surrounding rock pressure, the primary support at the arch waist bears great hoop stress, and the structure is compressed, and shear failure occurs	Both the left and right arches were damaged, and the structure is unsafe
II	DK390 + 520∼DK390 + 168	The left and right arches are easy to produce diagonal cracks and longitudinal cracks of about 1 m in length	Changing the scheme increases the rigidity of the structure, but the internal force of the structure increases. Once the internal force of the structure is greater than the ultimate strength of the material, the structure will crack	Cracking, peeling, and falling pieces occur at the arch waist, and the structural safety is insufficient
III	DK390 + 168∼DK390 + 152	Longitudinal cracks above the SRLD	The weak surface formed by the shotcrete above the SRLD is easy to crack and peel off	The vertical steel plate of the SRLD deforms and only accounts for about 10%, and the amount of deformation is less than 10% of the design estimate, and the structure is safe