ABSTRACT
It is important of maintenance strategy for it can ensure the infrastructures are managed to maximize the benefit of society. Condition based maintenance method aimed at promoting or maintaining the performance of structures in safe service condition in an economic, efficient and sustainable way. The application of this method can be divided into four steps: (1) Data acquisition. Getting the current service condition information timely and collecting inspection, repair or rehabilitation records as many as possible. (2) Performance prediction. Build mathematical or physical based models to assess the current condition and predict what will happen in the future. (3) Strategy optimization. Various factors are considered to minimize the lifecycle cost to give the best maintenance strategy. Optimization method is used in this process. (4) Implementation and feedback. Maintainers implement the optimal maintenance strategy, and collecting the feedback data to update the predictive model. This paper gives the procedure of executing condition based maintenance method of tunnel structures. Based on the defects of tunnels collected from manually record and some advanced automated inspection machine, a statistical predictive model is presented to show how the performance will develop without maintenance measures. With the consideration of maintenance cost and tolerant safety degree, an optimal model is generated to give the best maintenance strategy, which concerns how to decide the inspection interval and repair threshold to make life-cycle cost lowest. By using condition based maintenance strategy, it is convinced that the total maintenance cost of the tunnel can be reduced to keep the tunnel structure in a safety, reliable and serviceable condition during its designed life.
