Efficiency of Geosynthetic Lateral Drainage in Northern Climates

Abstract

During winter the formation of ice lenses causes frost heave within frost-susceptible materials. The uneven spatial distribution of heave due to heterogeneity results in severe damage to the pavement. Fissures are created, favoring excess infiltration, especially during subsequent springtime thaw. The installation of drainage can be beneficial in reducing the amount of water present in road foundations. Some uncertainty, however, exists about the sources of water feeding the lenses and, therefore, the optimal location of the systems. To assess the efficiencies of deep lateral drainage systems, a full-scale test has been undertaken along an existing road constructed on a glacial till subgrade. Three 150-m-long vertical geocomposite systems were installed at depths ranging between 2 and 3 m. In situ monitoring included piezometers and frost indicators and measurements of flow rates and pavement heave. To obtain a point of comparison, the measurements started 1 year before drain installation. For the period of observation the freezing indexes ranged between 1432°C-day and 1558°C-day, and the maximum frost penetration was 2.5 m. The flow rates varied considerably with the seasons, ranging between 1 ml/sec/linear meter during winter and 10 ml/sec/m during the April thaw. Before drainage the heave values ranged between 50 and 150 mm. After installation they were reduced by a factor ranging between 10 and 50 percent.