Challenges, Progress, and Prospects of Ultra-Long Deep Tunnels in the Extremely Complex Environment of the Qinghai–Xizang Plateau

With the implementation of significant national strategies and rapid socioeconomic development, many ultra-long deep tunnels are being constructed in the Qinghai–Tibet Plateau region. However, the extreme complexity and variability of the environment in this region pose significant challenges to the safe construction and long-term operation of the planned or under-construction ultra-long deep tunnels. To address these complex technical challenges, this paper provides a detailed analysis of the complex climate and geology of the Qinghai–Tibet Plateau in the context of tunnel construction. The climate characteristics of the Qinghai–Tibet Plateau include severe cold, low oxygen, and unpredictable weather changes. The geological characteristics include complex stress distributions caused by the intense internal and external dynamic coupling of tectonic plates, widespread active tectonic structures, frequent high-intensity earthquakes, fractured rock masses, and numerous active fault zones. Based on this analysis, this paper elaborates on potential sources of major disasters resulting from the characteristics of ultra-long deep tunnel projects in the Qinghai–Tibet Plateau region. These potential disaster sources include the crossing of active fault zones, high geostress rockbursts, large deformation disasters, high-pressure water surges, geothermal hazards, inadequate long-distance ventilation and oxygen supply, and multi-hazard couplings. In response to these challenges, this paper systematically summarizes the latest research progress and technological achievements in the domestic and international literature and proposes innovative ideas and future development prospects for disaster monitoring and early warning, mechanized intelligent construction, long-term safety services, and emergency security and rescue. These innovative measures are intended to address the challenges of tunnel disaster prevention and control in the complex environment of the Qinghai–Tibet Plateau, contributing to the safe construction and long-term operation of ultra-long deep tunnels in this region.