Abstract: The total length of the new line from the Ya′an to Linzhi section of the SichuanTibet railway is 1 018 km, of which the total length of the tunnel is 841 km, accounting for 82.6%. The longest tunnel is Yigong tunnel with a length of 42.4 km. The SichuanTibet railway tunnel project faces worldclass challenges such as extremely complex geological conditions, extremely huge engineering scale, extremely severe environmental conditions, and extremely sensitive ecological environment. It is the most complex and difficult tunnel project in China and even around the world. In this paper, ten major engineering technical problems that will be faced in the Ya′anLinzhi section of the SichuanTibet railway are preliminarily analyzed, and based on the extreme construction environment, countermeasures and suggestions are put forward regarding geological prospecting, route selection, construction organization, technology and equipment innovation, disaster prevention and mitigation, emergency rescue and environmental protection, etc. The results can provide reference for the survey, design, construction, operation, and maintenance of the SichuanTibet railway, and a series of innovations will help in realizing a strong "tunnel country" of China.

Key words: SichuanTibet railway tunnel, extreme environment, survey and design, construction organization, disaster prevention and rescue, environmental protection, technical problems, countermeasures and suggestions