Monitoring of the change of moisture beneath a railway embankment and the effectiveness of a wicking geotextile

ABSTRACT: A 45 m section of railway embankment was remediated on Canadian Pacific Railway’s (CP) Scotford subdivision to address issues of ongoing settlement and mud pumping. The track panel and embankment materials were replaced with new materials inclusive of a geotextile between the ballast and sub-ballast layers, and a wicking geotextile between the subgrade and sub-ballast. 5TE moisture sensors are installed at both the remediated section and an adjacent control section, along with access pipes for the use of a “Diviner 2000” probe to measure profiles of moisture with depth. This paper presents a comparison of the trends of volumetric water content (VWC) versus time between the two adjacent sites. The results are used to study the impact of precipitation events on VWC of soils and to interpret the effect of VWC on the unsaturated strength of the soil based on SWCC results. The early results of moisture-suction relationship shown that the strength of the subgrade material in the remediated section is improving; however, these trends are anticipated to be clearer with a full year of measurements.