Abstract:

Cracks of concrete lining structures of tunnels will affect the longterm operational performance of the tunnel and will lead to the durability degradation of the tunnel structure Due to the action of the running trains (vibration and aerodynamic effect), the micro cracks on the secondary lining of tunnels on passengerdedicated railways will expand and the operation safety of the tunnels will be affected As a result, it is of great necessity to study the control of the cracks of the secondary lining The internal temperature and humidity of the lining concrete are monitored by means of reserved holes in the concrete, and the variation of the temperature and humidity with time is obtained Meanwhile, the variation of the strain of the concrete during the construction period is obtained by means of embedding vibratingwire concrete strain gauges in the concrete lining The testing results show that the internal strain of the earlyage concrete has the variation rule that compressive strain occurs to the sidewall, tension strain occurs to the crown and the haunch is the transition zone Tension strain occurs to the crown, therefore the crown is the key point to control the cracks of the concrete lining 

Key words: tunnel lining, concrete, earlyage performance, temperature and humidity, concrete strain, field test