Measured Performance and Stability Analysis of Large-Scale Reinforced Model Embankments at Different Moisture Contents

Abstract

This paper describes construction and instrumentation of two 1.65-m high reinforced embankment models that were tested at two different gravitational water contents (GWC) on the dry and wet sides of the optimum moisture content (OMC); i.e. OMC−2 % and OMC+2 %. The embankment models were constructed using a clayey sand that was reinforced with four layers of instrumented geotextile with a uniform vertical spacing of 300 mm. Each model embankment was subjected to a line surcharge load (strip footing) near its crest until failure. The magnitudes of GWC, earth pressure, geotextile strains, footing settlement and embankment deformations were measured using EC-5 sensors, earth pressure cells, wire potentiometers, linear variable deferential transformers and reference plates, respectively during the construction and loading phases of each test. The GWC values in each model embankment were measured using EC-5 sensors and the oven drying method to ensure that they were close to the target values. Slope stability analysis was carried out to study the equilibrium of embankment models and to validate the predicted bearing capacity and factor of safety results against the experimental data. Results of this study show that the embankment model constructed on the dry side of OMC (i.e. OMC−2 %) had a 10 % greater serviceability failure load than the model built at OMC+2 %. Meanwhile, stability analysis results indicate that the bearing capacity of an unreinforced model embankment at OMC−2 % would be 72 % lower than that of the corresponding reinforced model. It is also found that compaction-induced energy could increase the earth pressure within the embankment by up to 70 % of the vertical stress in the soil mass due to gravity.