Mechanics State Analysis Of Secondary Lining On Tunnel Based On Temperature Effect

Mechanical behaviors of tunnel lining concrete influenced by periodic temperature variation are complicated when the operational tunnel is located in cold region. This paper bases on the Liujiaping tunnel groups which belong to NO.14 of National Trunk Qingdao-Yinchuan Shaanxi Habitat Wubao to Zizhou paragraph. By long-term monitoring of second lining concrete press, dealing and analyzing of monitoring data, and combined with data simulating calculation, we conclude the second lining concrete structure pressure properties along with temperature variation. Some valuable conclusions are gained as follows:(1) In the tunnel operation period, second lining concrete structure pressure changes as sine wave with time for the reason of period temperature variation. The press change curve and the temperature change curve along with time are of the same tendency, and the extreme press values of both curves emerge simultaneously.(2) Second lining press includes three aspects as follows, surrounding rock pressure, the dead weight of second lining and temperature press. The value of dead weight of second lining is constant, and surrounding rock pressure is stable on the whole, so the concrete thermal stress is the main reason that causes the second lining structure stress change as sine wave with time.(3) Simulation calculation of tunnel second lining structure-temperature press is carried out by software ANSYS, the results show that when cooling, the second lining concrete thermal stress is tensile stress, and tensile stress accretes when the temperature falling range increases. Under the identical temperature the maximum stress occur in the tunnel invert, temperature press changing as sine wave with time at the same spot, the results of which are commendably consistent with monitoring data.(4) To prevent the circumferential cracking of the second lining structure, the space between construction joint of the second lining structure were calculated, and the results of which show that the space between construction joint is related to temperature variation, and bigger the temperature variation, smaller the space of construction joint. The length of tunnel lining trolley can be chosen as below:in the southern region of China, it is appropriate 12m in construction process, and in north cold area, it should be 9m or 6m in accordance with different temperature variation of different location, meanwhile it can be lengthened relevantly when the tunnel lining trolley is far from the tunnel portal.