Search

Transverse passages are ubiquitous in urban subways, and they pose serious mutual threats to the two adjacent tunnels they connect. In this paper, the frequency sweep loads were applied in model tests and the influence mechanism of integral transverse passage (ITP) was studied by using the one-third octave of the frequency response function (FRF). Subsequently, a new assembled transverse passage (ATP) was proposed and its vibration attenuation effect was studied. The results showed that, when the frequency sweep load is applied to one tunnel, the adjacent tunnel is more susceptible to a load that has a central frequency of 12.5–80 Hz due to the existence of ITP. The closer the loading frequency is to 31.5 Hz, the greater the impact on the adjacent tunnel becomes. When an ATP is used, the vertical acceleration level (VAL) of the tunnel to which the load is applied will increase by 1.3 dB, while that of the adjacent tunnel will decrease by 7.2 dB, and the transverse passage will decrease by 8.7 dB. Compared to the ITP, when the lining structure of an adjacent tunnel is closer to the ATP, the reduction in the vibration response of the structure is more pronounced, and the vibration response is reduced over a larger central frequency range.

In cold regions, heat-insulating layers play a crucial role in frost prevention in tunnels. This paper presents a numerical study on the anti-freezing behavior of a cold region tunnel (the Dege tunnel) with heat-insulating layers. A numerical model based on the temperature field coupling theory is firstly proposed and validated using field test data of the Dege tunnel. Subsequently, a comprehensive parametric study is carried out to investigate the influences of heat-insulating layers on the temperature characteristics of airflows inside the tunnel, the surrounding rock, and the tunnel lining. Furthermore, a numerical investigation based on the proposed numerical model is carried out to propose reasonable design parameters of heat-insulating layers for different velocities of mechanical ventilation, and different heat-insulating materials for cold region tunnels. The numerical results show that using the heat-insulating layer can effectively reduce the heat transfer between the surrounding rock and the airflow inside the tunnel. It is also found that the design parameters for the heat-insulating layer are greatly affected by the tunnel ventilation conditions and heat-insulating materials.