对流-导热耦合作用下保温层对寒区水工隧洞衬砌结构力学特性的影响

Effect of Convection-thermal Coupling Insulation Layer on Structural Mechanical Characteristics of Hydraulic Tunnel Lining in Cold Area

以新疆布伦口水电站引水隧洞为例,考虑对流-导热作用,通过现场监测成果和有限元仿真计算,分析引水隧洞在不同位置铺设不同厚度的保温层对衬砌结构热-力耦合特性的影响。结果表明,表面铺设时,保温层厚度与衬砌的冻胀力呈负相关,且当厚度在0.06 m以上时,二次衬砌的冻胀力变为压应力;保温层厚度与衬砌的横向位移呈正相关,与纵向位移呈负相关。夹层铺设时,保温层厚度与二次衬砌的冻胀力呈正相关,与一次衬砌的冻胀力呈负相关;随着保温层厚度的增加,二次衬砌的最大主应力变为拉应力,不利于二次衬砌的安全稳定;随着保温层厚度的增加,一次、二次衬砌的横向位移差值增大近4倍,纵向位移差值增大10倍以上。

Taking the diversion tunnel of Xinjiang Bulunkou Hydropower Station in Xinjiang as an example,considering the convection-heat conduction effect,the effects of insulation layers with different thicknesses on the thermal-force coupling characteristics of lining structure at dfferent locations of diversion tunnel are analyzed based on the results of on-site monitoring and finite element simulation calculations.The results show that,when the insulation layer is laid on the surface of secondary lining,the thickness of insulation layer is negatively correlated with the freezing and expansion force of the lining,and when the thickness is above 0.06 m,the freezing and expansion force of the secondary lining becomes compressive stress;the thickness of insulation layer is positively correlated with the transverse displacement of the lining and negatively correlated with the longitudinal displacement.When the insulation layer is laid between primary lining and secondary lining,the thickness of insulation layer is positively correlated with the freezing expansion force of the secondary lining,and negatively correlated with the freezing expansion force of the primary lining;with the increase of the thickness of insulation layer,the maximum principal stress of the secondary lining becomes tensile stress,which is not conducive to the safety and stability of secondary lining;with the increase of the thickness of insulation layer,the difference in transverse displacement between the primary and secondary lining increases by nearly 4 times,and the difference in longitudinal displacement increases by more than 10 times.