Stability analysis of tunnels of the Gaoligong Mountain for Dali-Ruili railway, western Yunnan Province

The Dali-Ruili railway constitutes the critical part of the Trans-Asian railway system. It runs through the southern stretch of the Hengduan Mountains with complicated topographic and geological conditions. The engineering stability of the Gaoligong Mountain deep-lying extra-long tunnel has long been a thorny problem affecting route choice and road construction. Based on regional geology, stress measurements, and rock mechanism, the authors conducted finite element calculation of the stress distribution of tunnel profiles, created stress-distribution images, and evaluated the impact of the shape of the tunnel profile on stress distribution, by using ANSYS software. The authors also made an analysis of country rock stability from different tunnel profiles and calculated the ratio between the strength and the stress of the wall rock. In the end, a comprehensive estimation is made concerning tunnel stability on different profiles, and some key problems are put forward which deserve attention in tunnel design and construction.