Structural deformation monitoring and service reliability analysis for slab track in plateau areas.

How to effectively monitor the structural condition of slab track and determine its service reliability is a key problem to be solved in the development of high-speed rail (HSR) lines in plateau areas, due to the influence of extreme climate, such as low air pressure, dryness and large temperature difference. To this end, this paper first develops an online displacement monitoring system for double-block slab track. Considering the actual operation condition of the HSR line, this system uses the non-contact vision sensing technique to measure the slab displacement. The slab temperature is also measured synchronously by the system. Then, the relationship between atmospheric temperature and the displacement of the slab track is discussed. The monitoring data are grouped according to three temperature states when being collected: stable temperature, rapid temperature rise, and rapid temperature drop. Finally, the serviceability limit state (SLS) equation of slab track is established and the service reliability of slab track under three temperature conditions is calculated using Monte Carlo method. The results show that track slab deformation is highly sensitive to temperature change and can significantly affect the service reliability of the slab track; compared with the period of "stable temperature", when the temperature rises rapidly, the reliability index of the slab track decreases from 4.48 to 3.92 and the corresponding failure possibility increases around 12 times. This research can provide data support and theoretical basis for intelligent health management of the HSR slab track in the plateau area. [ABSTRACT FROM AUTHOR]