Determining the Elastic Deformation Modulus From a Compacted Earth Embankment Via Laboratory and Ménard Pressuremeter Tests

Abstract

Compacted earth embankments are routinely used in dams and many others infrastructure projects in Brazil. It is common to use fine-grained soils for these embankments, which are placed and compacted in the field at specific values of unit weight and water content. Their design is usually performed using geotechnical parameters from laboratory tests on compacted samples, although in situ tests could emerge as an alternative for determining specific parameters, as such tests can be conducted reasonably rapidly and can somewhat account for local inherent conditions of the soil such as confining stress levels, water content and mineralogical variations. Therefore, this paper explores the application of Ménard-type pressuremeter tests to determine the Young’s modulus of compacted soil layers from the side flank of a large-scale earth embankment constructed in the city of Goiânia in the Midwest Region of Brazil. The embankment was compacted under controlled conditions, permitting the extraction of undisturbed soil blocks at distinct levels during its erection. Laboratory tests, such as consolidated isotropic triaxial and oedometer tests, were performed on samples at their natural water content. Young’s moduli were derived from these laboratory tests and compared with the elastic moduli measured using the pressuremeter, either directly under different (external) conditions or at normalized levels of the effective confining octahedral stress. This comparison of results enabled the establishment of preliminary statistical correlations between the average (in situ and laboratory) moduli, which will be useful when using the Ménard pressuremeter for a preliminary design or a post-construction check of compacted earth embankments.