Geogrid-reinforced roadway embankment on soft soils: A case study

Building earth structures on soft soils is one of the toughest challenges in civil engineering. Due to the fill embankment and surcharges, the settlements associated to the overburden pressures are one of the major concerns in roadway embankment construction. Several methods of support improvement have been in practice for years (e.g. excavation/fill replacement, stone filling, Corduroy, etc.), but recently, geosynthetic reinforcement has been successfully incorporated as an efficient way to improve the weak soil conditions. This paper focuses on a case study that introduces a geogrid-reinforced roadway embankment located in the Texcoco Lake, near Mexico City, Mexico. The structure consists of an embankment with variable heights to be built in two different conditions: dry and saturated. The most critical section was in the saturated zone (take) where the maximum embankment height was 2.80m and the water level was at 1.80m, leaving only 1.0m of dry embankment body. The embankment was built on highly compressible saturated clay layers up to 40.0m deep, and moisture of up to 300%. The paper presents project design information, settlement observations, and performance evaluation. The performance of the embankment was observed during and after construction using inclinometers, and deep and surface surveying equipment. A presentation of this performance and results about the predicted vs. actual embankment settlements are included in the paper.