Crack Identification Method for Prefabricated Concrete Pavement Based on Distributed Strain Monitoring

It is meaningful to monitor and identify concrete cracks as they will seriously reduce the fatigue life of pavement. In this paper, a new method based on distributed long-gauge optic fiber sensing is proposed to implement crack identification. Firstly, the damage indicator, namely strain curve envelope area ratio (SCEAR), is proposed and calculated with the measured strain in time series when the plane goes across the pavement where the sensors are installed. Then, the indicators with different sensors are normalized by the value of the indicator from one referenced sensor where damage normally will not happen. If the crack happens within the sensing gauge of the sensor, the value of the damage indicator SCEAR from the sensor will increase. Therefore, the crack will be identified with the change of the damage indicator. The effect of the proposed method is first verified by some simulations of prefabricated pavement as the cracks can be accurately identified by the proposed method. Moreover, the influence of the aircraft, such as taxiing position, aircraft load, and aircraft type, is not obvious enough to mislead the identification results. Lastly, the static loading tests were implemented with one small-scale model of prefabricated concrete pavement in the lab. From the experimental results, the prefabricated cracks inside the pavement slab can be identified accurately with the proposed method as the parameter SCEAR is increased by about 100% at the crack position, while it is only changed by about 3% at the undamaged position.