Abstract

In Japan, many tunnels have been in service for several decades, which require effective inspection methods to assess their health conditions. The ambient vibration test has attracted more and more attentions in the recent studies for health management of concrete structures. In this study, the vibration characters of tunnel lining shells built with poling-board method was analyzed by application of the analytical solutions of the Love-Timoshenko shell theory and Donnell-Mushtari shell theory. The natural frequency estimated by Love theory is slight smaller than that of Donnell theory. The rock-concrete contacts, including the poling board and interfaces between rock mass and concrete lining, was represented by elastic boundaries with normal and shear stiffness. It was found that the stiffness of weak contacts has the great effect on the natural frequency of the lining. Numerical simulations were also carried out to compare with the results of the proposed method, even though the low natural frequency is difficult to distinguish. It is possible to conclude that the proposed approach is convenient, effective and accurate.

1. Instructions

Japan is a country surrounded by sea and 70% of its land is covered by mountains. More and more tunnels through mountains have been constructed during the last 50 years, and those tunnels have become an indispensible part of the traffic networks. The persistent ageing of tunnels causes many problems on the lining of tunnel, such as corrosion, buckling, fracturing, the creation of internal voids and the seepage induced by flaws (Malmgren et al. 2005). Deteriorations and damages of lining concrete decrease the integrity of tunnel lining and subsequently affect the workability, serviceability and safety reliability of tunnels (Aktan et al. 2000, Bhalla et al. 2005). Therefore, appropriate inspection needs to be conducted at appropriate time to ensure the effective function of tunnel.

To date, a number of inspection methods including destructive and nondestructive approaches have been proposed and used in practices to evaluate the tunnel integrity. However, these methods can only provide local information and require considerable time and cost to estimate overall tunnel integrity (Park & Choi 2008).With the development and application of high sensitivity accelerometer, the low-cost ambient vibration test has attracted much more attentions for evaluating the structural condition of the whole structure. Therefore, it is important to study the analytical solutions of tunnel lining vibrations with an appropriate model in order to better understand its dynamic behaviors.

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