GEOTEXTILE STRAIN IN A FULL-SCALE REINFORCED TEST EMBANKMENT

A geotextile reinforced test embankment was constructed on a soft organic clayey silt deposit at Sackville, New Brunswick, Canada in September/October 1989. A relatively high-strength polyester woven geotextile (ultimate strength of 216 kN m(-1)) was used as reinforcement. The reinforcement was instructed with a number of electrical resistance, electro-mechanical and mechanical gauges. The details of this instrumentation and field performance of the geotextile reinforcement during the construction of this test embankment are described in this paper. The field data indicated that the strain in the geotextile was comparatively small (typically less than about 0.7%) up to an embankment thickness of 3.4 m. The strain increased to a maximum of about 2% when the embankment thickness was increased about 4.1 m, suggesting the initiation of movement (or yielding) of the foundation soil. A large increase of strain was evident for thickness exceeding 5.7 m and the available evidence indicates that the soil approached failure at a fill thickness of about 5.7 m. The strain increased to over 8.5% when the embankment was first constructed to 8.2 thickness and then failed as the soil continued to deform at constant fill thickness and the geotextile strain increased until failure (inferred tearing) of the geotextile occurred. After the embankment failed at a thickness of 8.2 m, the addition of more fill did not result in any increase in the net embankment height of 6.6 m, reached just prior to failure of the geotextile. However, although the embankment exhibited signs of distress and large deformations, there was no classical rotation collapse at 8.2 m fill thickness.