Abstract:

The total length of the tunnels on Zhengzhou～Xi’an passengerdedicated railway is over 60km, two thirds of which is located in Q3 and Q2 old/new loess. Due to the features of the loess and the terrain, portal types and the bridge abutments stretching into the tunnels, a lot of high loess slopes exist at the tunnel portals. The stability of the slopes becomes one of the critical aspects of the works. In the paper, the stability of the front and side portal slopes of the tunnels is verified by means of limit equilibrium theory based slice method and the design of the slopes is optimized so as to meet the requirements of the safety coefficient specified in relevant codes. The dynamic response of the large crosssection shallow tunnels in new sand loess under viscouselastic boundary is calculated by means of transient dynamic FEM so as to find out the weak points of the lining and the stress, deformation and safety of the tunnel structure. The paper can provide reference for the design of similar works in the future.

Key words: passengerdedicated railway  , loess tunnel  , collapsible loess  , stability of high portal slope  , seismic response