Abstract:Research purposes: The environment temperature of the structure in shallow section of the tunnel in the permafrost area is mainly influenced by the atmospheric temperature. The water above frozen layer is easy to converge around the tunnel opening because of the large amplitude of change of temperature and the thawing circle caused by construction approaching to or overlapping the top limit of permafrost during the construction. Therefore, the damage phenomena like lining cracking, water leakage and ice covering easily happen to the parts of the tunnel in such area. The possible damage to the supporting structure for the tunnel caused by the freezing and thawing cycle can be reduced or avoided by using the active cooling protection for the surrounding wall in the tunnel shallow section in permafrost area.
Research conclusions:(1) By using the thermal probe group, the temperature of the surrounding wall will be significantly reduced within its sphere of influence, the strength of the surrounding wall of permafrost will be enhanced, and the top limit of the permafrost will be raised to form a waterproof curtain on the tunnel ceiling for reducing the frost heaving force on the tunnel supporting structure.(2)The water above frozen layer can’t infiltrate into the tunnel structure and the refreezing time will be reduced from 3 to 5 freezing and thawing cycles to 1 cycle. In this way, the problem of the freeze-thawing damage to the supporting structure in the portal section can be solved.(3)This technology has features of lower engineering cost and more convenience in terms of installing and monitoring. (4)This research achievement can be used for the disease control and treatment of the shallow section of tunnel in the permafrost area.
刘锟;蔡汉成;李奋. 热棒群在多年冻土区隧道浅埋段防护中的应用[J]. 铁道工程学报, 2013, 30(9): 60-64.
LIU Kun, CAI Han-cheng, LI Fen. Application of Thermal Probe Group in Protection of Shallow Section of Tunnel in Permafrost Area. 铁道工程学报, 2013, 30(9): 60-64.
Niu Dongxing, Li Yong, Xiong Zhiwen, etc. Tibet Railway Permafrost Ground Temperature Hot Rod Field Analysis [J]. Journal of Railway Engineering, 2012(9):30-33.