隧道地源热泵热交换管换热引起的温度应力研究

Research on temperature stress induced by heat exchange pipes of ground source heat pump buried in tunnels

为解决寒区隧道冻害问题,将地源热泵型供热系统应用于内蒙古博牙高速扎敦河隧道研究中。系统由取热段、加热段、热泵和分集水管路组成,可用于隧道洞口段衬砌和保温水沟加热。热交换管以串联纵向的布置形式埋设在初衬与二衬之间。系统运行时,热交换管换热引起周围衬砌温度场的变化,从而在衬砌内产生温度应力。根据扎敦河隧道实际大小,建立有限元分析模型,计算得到热交换管换热引起的温度和应力。研究结果表明:系统运行后,管周混凝土有明显的温度集中和应力集中,但影响范围小;运行期间,混凝土温度呈指数形式减小,并有一定的波动范围;温度应力以拉应力为主,并且径向温度应力小于环向温度应力;运行期间,径向温度应力变化率较小,而环向温度应力变化率较大,但长期运行后,环向温度应力趋于稳定。

Tunnel heating system using heat pump was introduced at Zhadun River tunnel in Inner Mongolia Autonomous Region of China to prevent freezing damage in cold region tunnels. Tunnel heating system consists of the heating section, absorbing section, heat pump, collector and distributor line. This system can be used for heating lining and insulation ditch in tunnel portal. The heat exchange pipes were laid between first lining and second lining in series of longitudinal arrangement. The temperature field of lining was changed to cause temperature stress by heat exchange pipes when the system was operated. According to the actual size of Zhadun River Tunnel, the finite element analysis model was established to calculate the main characteristics of temperature and stress casused by heat exchange pipes. The results show that the temperature and stress concentration are significant after operation of the system, but the incidence is small.The concrete temperature exponentially decreases with a certain of fluctuation during operation. The temperature stress is the main tensile stress, and the radial temperature stress is much smaller than the hoop temperature stress. The change rate of radial temperature stress is small and the change rate of hoop temperature stress is large during operation, but the hoop temperature stress tends to be stable after long-running.