Abstract:

With the rapid development of traffic infrastructure construction in western mountain area, the lining-stratum interaction mechanism of mountain tunnel under seismic effects has attracted increasing attentions. Based on the prototype of a regular two-lane highway tunnel section with V-grade surrounding rock, a static pushover model test for mountain tunnel was conducted. The variations of stratum displacement, stratum strain and ground pressure with pushover distance were carefully studied, and the lining-stratum interaction mechanism was thoroughly discussed. The test results show that: the lining-stratum interaction can be generally divided into compacting stage, overturning stage, and dragging stage. The stratum tends to circumferentially flow along the lining perimeter from the springing line in the overturning stage, and then drives the lining to shift together in the dragging stage. The stratum near the springing line experiences predominantly radial compression, forming a compression deformation zone, while the stratum near the lining shoulder mainly undergoes circumferential compression, forming a slip deformation zone. The response of the ground pressure on the left and right sides are exactly opposite. Specifically, the ground pressure in the compression deformation zone on the right side is greater than its counterpart on the left side, while the ground pressure in the slip deformation zone on the right side is less than its counterpart on the left side. These researches can provide some experimental basis and technical support for the anti-seismic calculation of mountain tunnels based on response displacement method.

Key words: mountain tunnel, lining–stratum interaction mechanism, static pushover model test, digital image correlation, ground pressure