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寒区冻融环境下,隧道衬砌普遍存在开裂、剥落、挂冰以及路面冒水、结冰等冻害,严重危及隧道的运营安全。结合大坂山隧道的实际工程情况,从隧道的冻害成因和冻胀机理出发,分析了围岩的冻胀膨压力对衬砌结构的作用特性和规律,以及衬砌混凝土在冻融作用下的损伤情况,得出主要结论有:围岩冻胀膨压力是影响隧道衬砌耐久性的主要因素;拱脚在断面内最先达到最不利状态,混凝土自身的特性直接影响其抗冻融破坏能力。并据此提出可行、有效的技术对策,对提高寒区冻融环境下隧道衬砌耐久性具有参考意义。
Under the freezing and thawing environment in cold area, tunnel linings are generally cracked, spalling, hanging ice, freezing and damping on the pavement, causing serious damage to the tunnel’s operation safety. Based on the actual engineering conditions of the Daanshan Tunnel and the causes of frost damage and the frost heaving mechanism of the tunnel, the characteristics and regularities of the freeze-swell pressure on the lining structure and the damage of the lining concrete under the freeze-thaw condition are analyzed. The main conclusions are as follows: The swelling and swelling pressure of surrounding rock is the main factor affecting the durability of tunnel lining. The arch foot reaches the most unfavorable state first in the section, and the concrete’s own characteristics directly affect the anti-freeze-thaw damage ability. Based on this, a feasible and effective technical countermeasure is proposed to improve the durability of tunnel lining in freezing and thawing environment in cold area.