Arching effect in a full-scale reinforced piled embankment on very soft soils, considering long-term performance and plate load tests

• Pressure on the pile caps is up to 8 times greater than the pressure on soil. • Similar arching ratios were reached with measured and computed numerically. • Measured pressure differs from those using well-recognized analytical solutions. • Plate load tests on GR-piled-embankment also exhibits a marked arching effect. • The arching ratio exhibits cyclic annual fluctuations due to stationary rainfall. Piled embankments with basal geosynthetic reinforcement for supporting roads, airstrips, and railways, and other infrastructure projects on soft soils, are particularly effective in reducing the time between construction and the beginning of operation. This paper presents the measured vertical pressures at the base of a test piled embankment on the very soft clayey soils of the former Texcoco Lake near Mexico City. Pressure cells were placed directly on the ground surface and, at the same level, on pile caps. The 2.1 m-high embankment, resting on friction piles, was composed of volcanic scoria, gravel-sand, and a flexible pavement. Monitoring a full-scale prototype for almost 5 years provides a comprehensive understanding of the arching effect over the long term. Through this mechanism, piles take, in this case, as much as eight times more vertical pressure than the surrounding soil (arching ratio). However, measured pressures on pile caps and surrounding soil differ from those obtained using well-recognized analytical solutions; these, in turn, differ from numerical solutions. Similar arching ratios were reached with measured and computed numerically. A cyclic annual rainy station effect that reduces this ratio was evident. Seismic events also cause a slight reduction in the arching ratio, with a quick recovery. Considering the possible use of this embankment type in some areas of an airport, static load plate tests were conducted to reproduce the stresses a front axle tire of an Airbus A-380 produces during a braking stop. Under these tests, we verified that the soil arching mechanism is indeed present.