It is inevitable to encounter any problems that the tunnel projects could be possible to adopted in the vicinity of the fault or high-intensity earthquake area during the construction of the traffic engineering in Western China regions (in particular the South-West). The line from Ya’an to Lugu highway is across the seismic faults several times (Xianshui River fault zone and Anning River fault zone) and the seismic fortification intensity is from Ⅶ degrees to Ⅸdegrees, in particularly Ⅹ degrees at local regions. The peak acceleration of ground motion is from 0.15g ~ 0.4g, which parameters are the relative large in the current construction of the highway.

In this paper, the dynamic characteristics of tunnel structure is analyzed at the mountain tunnel portal according to the actual engineering, thus the law of stress-strain and failure mode of the tunnel and surrounding rock are researched under the ground motion load, which provides an important reference for the design and construction of the highway tunnel in high-intensity earthquake area.

2 Relying on engineering conditions and shaking table test device

2.1 Geological conditions

Model test was accomplished in august 2007, based on certain tunnel project where there is through the region of seismic fortification intensity Ⅸ degrees and may be active faults in Ya-Lu highway. Based on drilling and surface survey, the tunnel stratum is mostly triassic system~Jurassic system, silty mudstone, pelitic siltstone, quartz sandstone, carbargillite, Cenozoic overlying Holocene Quaternary cover.

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