Abstract: Tunnel safety under earthquakes in loess area has become an increasingly prominent problem along with the intensifying of investment on railway construction in central and western China according to Belt and Road Initiative proposed by China. Some built projects such as Baoji-Lanzhou high-speed railway and Lanzhou-Chongqing railway, and railways under construction, including Chengdu-Lanzhou Railway and Xi’an-Yinchuan Railway, are all running across the loess seismic belt. For a long period of time, the elevation of tunnel entrance, which is an important parameter affecting the dynamic response of loess slope-tunnel system, has received few attention. In view of this, the dynamic response of loess slope-tunnel system is investigated with tunnel entrance elevation as a key parameter via shaking table test and numerical simulation. The similar ratio of slope-tunnel model was 1∶70, and the elevation of tunnel entrance was designed as zero (slope foot) and 1/2 times of slope height, respectively.Test results demonstrate that at different elevations of tunnel entrance, the failure pattern and damage degree of entrance segment are quite different despite the same conditions of slope height, slope gradient, incident earthquake wave, geomaterials, filling mode, and lining structure. The impact of entrance elevation on the acceleration in lining structure is closely related to the magnitude of the excitation amplitude, and the acceleration response of the tunnel lining structure with the entrance elevation at slope foot is much smaller than that with the entrance elevation 1/2 times of the slope height.

Key words: shaking table test, dynamic response, side heading slope, lining structure, failure characteristic