Abstract:

Temperature in tunnel and temperature of surrounding rock which distribute in distinct regions and mountains are always different, and even have great differences sometimes. Accordingly, although under the same pouring materials and operating conditions, the temperature and the thermal stress of the lining concrete which will affect the occurrence and control of the temperature cracks to a great extent are also different. Taking Xiluodu free-flow tunnel as a research object, a 3-D finite element method is applied to simulate the construction process under conditions of different air temperatures in tunnel and temperature of surrounding rock. Through comparing the maximum temperature, maximum temperature difference between inner and surface, minimum temperature, maximum tensile stress in early period and winter, the effects of the change of temperature in tunnel and surrounding rock on the temperature and thermal stress of the lining concrete as well as occurrence, development and control of the temperature cracks are analyzed. The results show that both the temperature in tunnel and the temperature of surrounding rock have significant influences on the temperature field and stress field of the lining concrete. The lower the air temperature in tunnel is, the easier the early cracks will occur in winter; and it is necessary to prevent both early cracks in summer and winter cracks. The tensile stress of the lining concrete increases obviously when the temperature of the surrounding rock is low, however, the effect on the stress of the surface and inner is small; so the temperature of the surrounding rock has little effect on the temperature cracks. The research results provide valuable references for the design and construction of tunnel engineering.

Key words: flood discharge tunnel, lining concrete, temperature in tunnel, temperature of surrounding rock, thermal stress, temperature crack