Full-scale laboratory testing of a geosynthetically reinforced soil railway structure

Abstract

Railway lines typically use traditional sloping embankments as the principal means of track support. However, the use of Geosynthetically Reinforced Soil (GRS) systems have gained popularity as alternatives to conventional embankments, particularly for high-speed lines in Japan. This system requires less ground stabilization/improvement and less land take than conventional embankments due to its smaller base area. This research investigates the immediate and long-term settlement behaviour of a Geosynthetically Reinforced Soil with Retaining Wall (GRS-RW) system subject to cyclic loading for two track forms: a concrete slab track and a ballasted track. First, a three-sleeper concrete slab section is constructed at full-scale under controlled laboratory conditions, followed by a ballasted track. Both are supported on a 1.2 m deep subgrade and a frost protection layer in accordance with railway design standards. Two different axle load magnitudes are applied statically, and then cyclically/dynamically, using 6 actuators to replicate moving train axle loads. It is observed that the slab track performs significantly better in terms of elastic and plastic deformation under both static and cyclic loading. Overall, the amplitude of the rail displacement under an individual cycle loading was approximately 25% lower for the slab track and the amplitude of the sleeper displacement on the ballasted track was approximately 6–7 times higher.