考虑相变和围岩含水裂隙的隧道冻胀力研究

Research on the Frost Heaving Force of Tunnel Considering Phase Change and Water-bearing Fracture of Surrounding Rock

研究目的:为掌握寒区隧道冻胀力特征,以2022年冬奥会重大交通保障项目金家庄特长螺旋隧道为依托,通过室内试验、温度测试和COMSOL数值模拟相结合的方法,建立仅考虑围岩冻胀的计算模型,研究相变潜热和围岩含水裂隙对衬砌结构和围岩内力的影响。研究结论:(1)考虑相变潜热能减少衬砌结构内力,相变潜热对衬砌结构冻胀内力的影响随着计算时间的增加愈加明显;(2)含水裂隙使初期支护的最大拉、压应力增大,而使二次衬砌的最大拉、压应力减小,且对初期支护的最大拉、压应力影响明显大于二次衬砌结构,相对于无围岩裂隙,含水裂隙的存在推迟了衬砌结构应力出现的计算时间并使围岩各截线位置的第一主应力变化规律由W型转变为V型;(3)相变潜热和含水裂隙对衬砌结构的最大拉、压应力位置,衬砌结构和围岩的主应力分布规律及量值大小均有一定影响,实际工程中应注意减小围岩裂隙对结构的影响;(4)本研究结论可为类似高寒地区相变潜热和围岩含水裂隙对隧道冻胀力的影响大小提供借鉴或参考。

Research purposes:In order to master the characteristic of frost heaving force in cold region,based on the2022 Winter Olympics Games significant traffic security projects Jinjiazhuang extra long spiral tunnel as the backing,through indoor experiment,temperature test and COMSOL numerical simulation,the calculation model only considering the frost heave of surrounding rock is established,and the influence of phase change latent heat and water-bearing fracture on the internal force of lining structure and surrounding rock is studied.Research conclusions:(1)The phase change latent heat has greater influence on the internal forces of the lining structure,with the increase of computing time,the influence degree becomes more obvious,considering that the phase change latent heat can reduce the internal force of the lining structure.(2)Water-bearing fracture will increase the maximum tensile and compressive stress of initial support,while decrease the maximum tensile and compressive stress of secondary lining,and its influence on the primary support is obviously greater than that of the secondary lining structure.The existence of water-bearing fracture delays the calculation time of the stress occurrence of the lining structure,the water-bearing fracture will change the change rule of first principal stress of the lining structure from W-type to V-type.(3)The phase change latent heat and water-bearing fracture have certain effects on the maximum tensile and compressive stress position of lining structure,the main stress distribution law and magnitude of the lining structure and surrounding rocks,the influence of surrounding rock crack on the structure should be reduced in practical engineering.(4)The research conclusions can be used as reference for the effect of phase change latent heat and water-bearing crack in surrounding rock on tunnel frost heaving force in similar high cold regions.