Railroad track substructure monitoring using Ground Penetrating Radar (GPR)

摘要

The general condition of the subsurface region of a railroad track has great impact on track integrity and performance. The track substructure consists primarily of three layers: the ballast, the subballast, and the subgrade. The ballast is the top layer, and consists of crushed rock of size 2.5-6.5 cm. The ballast thickness typically ranges between 30 and 45 cm. The important functions of the ballast are: (a) resist vertical, lateral, and longitudinal forces applied to the ties, (b) provide resiliency and energy absorption for the track, (c) provide voids for storage and movement of fouling material, (d) facilitate track geometry adjustment by tamping, (e) provide immediate drainage of water, and (f) reduce pressure from tie earing areas to acceptable levels for the underlying materials [1]. The subballast is the middle layer, and consists primarily of coarse grained material consisting of sand and gravel particles.