Abstract:

The on-site monitoring and analysis results reveal that on the construction site of Tianmushan Tunnel on Hangzhou-Huangshan High-speed Railway, the average specific activity of the radioactive nuclide 238U reaches 236.3 Bq/kg, higher than the state average of 39.5 Bq/kg; the maximum concentration of vanadium in the tunnel reaches 77.88 μg/m3, 1.6 times the occupational limit; and the amount of the toxic gases such as SO2 and CO produced by blasting are dozens of times of the safety limit. The construction of tunnels in hazardous gas and radiation environment is complicated and difficult, which lacks similar engineering experience. As a result, the theoretical calculations and field tests are carried out, targeted measures such as advance pre-grouting, lining structure reinforcement, ventilation strengthening, dust reduction by water curtain, etc. are adopted to effectively avoid the radiation effect. The total effective annual dose of construction workers is 0.386 mSv, which is below the target management limit of 1 mSv. The concentrations of toxic gases, dust and vanadium are also lower than the detection limits. The results show that the adopted technical measures have remarkable effect on the treatment of tunnel construction in toxic gases and radiation environment, which can ensure the safety of construction personnel and construction progress and the safety of railway operations. The results can provide reference for similar projects in the future.

Key words: railway tunnel, toxic substances, radiation, pre-grouting, monitoring