Abstract: The tunnel excavation will result in the stress redistribution in the surrounding rock mass and therefore induce an adverse effect on the lining of the existing adjacent tunnels. The proposed Anjiazhuang Tunnel, which is funded by Shaanxi Tongchang Energy Co., is adjacent to the rail lines of Wari and Xiaojiawa. Since the edge of the proposed tunnel is only 1.1 meters to the tunnel of Xiaojiawa line and 19.7 meters to the tunnel of Wari line, the tunnel excavation might post a serious safety hazard to the operational adjacent tunnels. This paper presents the numerical evaluation results of the stress redistribution in lining of the adjacent tunnels during the new tunnels excavation based on the actual rail tunnel locations, geological conditions and tunnel structural and geometries. A quantitative safety evaluation was performed at the most unfavorable locations at both sides of the tunnel linings in accordance with the current railway safety codes. 

Key words: Tunnel Excavations, Existing Adjacent Tunnels, Numerical Simulations, Safety Assessment