Estimating Embankment Settlement from Piezocone Penetration Test Data

Abstract

The in situ piezocone penetration test (PCPT) has been widely used by the geotechnical engineering community for subsurface soil identification and classification and for the evaluation of many engineering soil properties, such as consolidation parameters. PCPT-derived consolidation properties can be used to estimate the magnitude and time rate of the consolidation settlement of loaded soils. This paper presents a case study on implementing PCPT technology to evaluate the embankment settlement at the Juban Road-I-12 Interchange Bridge in Louisiana. The soil underneath each embankment site of the bridge was instrumented with a horizontal inclinometer and vertical magnet extensometers. In each embankment site, PCPT tests were performed, and the soundings of cone tip resistance were used to estimate the constrained modulus (M) profiles. Dissipation tests were conducted at specified penetration depths and used to estimate the vertical coefficient of consolidation (cv). Shelby tube soil samples were collected and tested in the laboratory to evaluate the consolidation properties. The embankments’ consolidation settlements were monitored with time, and the field-measured values were compared with the magnitude and rate of settlements estimated with parameters derived from PCPT data and laboratory consolidation tests. The piezocone penetration and dissipation data reasonably estimated the magnitude and rate of consolidation settlement of both embankment sites. The backcalculated M and cv parameters from field measurements were in good agreement with PCPT-derived values.