Settlement characteristics and engineering significance of subgrade surface for railway passenger dedicated line

Subgrade surface settlement is a basic content of deformation observation and settlement assessment for railway passenger dedicated line; but the application of observation accomplishment has some falsehood because of insufficient understanding of the physical meaning and engineering significance of subgrade surface settlements. With a large number of settlement observation data of subgrade in Wuhan-Guangzhou railway passenger dedicated line, the settlement characteristics and symbolical meanings of subgrade surface are analyzed; and the reasonable application method of the observation accomplishment is discussed. The analysis shows that the settlement observation data of subgrade surface may be used to investigate the stability and the developing tendency of subgrade settlement, and whether the correlation coefficient of curve regression meets the requirement, however, that it cannot be used to calculate post-construction settlement. A calculating method for post-construction settlement is suggested by combining the measured data of subgrade surface settlement and ground settlement.