Numerical Study of Uplift Induced Levee Failure for the Design of a Centrifuge Test

Abstract

In geotechnical engineering, physical and numerical models seek to shed light on multiphase phenomena that threaten earth structure stability. This is the case of river levees: when subjected to non-ordinary hydraulic loads, local and global failures with consequent floods could occur. If, on one hand, centrifuge models can replicate the real phenomena, exploiting the enhanced gravity, while scaling geometrical features and time, on the other, numerical models extend the possible case studies by capturing key elements, governing the hydromechanical behaviour of the earthworks. However, the two techniques could complement and benefit each other. In this research, a potential failure mechanism, induced by the development of uplift pressures beneath the toe of a levee characterized by a peculiar stratigraphic profile, is investigated. The foundation consists of a shallow weak low-permeability layer, overlying a coarser and more permeable one, this latter acting as a hydraulic preferential flow path between riverside and landside. Results of a preliminary numerical study carried out with different methods are presented and discussed. The study aims to improve understanding of complex failure mechanisms and to encourage the development of more robust forecasting methods. Indeed the results have provided fundamental guidance for a centrifuge experimental set up.

Soil water retention curves of a silty clayey sand compacted at different dry density

“…Embankments built along the tributaries of the Po River (Italy) are generally composed of a heterogeneous mixture of sand, silt and sometimes clay, and frequently founded on clayey and silty deposits. To experimentally characterize a material for a river embankment to be reproduced in geotechnical centrifuge tests [8,9] within the PRIN 2017 project called "Risk Assessment of Earth Dams and River Embankment to Earthquakes and Floods (REDREEF)", a mixture consisting of 70% Ticino Sand (TS) and 30% Pontida clayey sandy silt (PON) was selected (TS70%-PON30%). Here, the soil water retention curves determined on three mixtures TS70%-PON30%, compacted at different water contents and initial dry densities are carried out.…”

Analysis of transient seepage through a river embankment by means of centrifuge modelling

“…The hydro-mechanical properties of the mixture are discussed in [10][11]. Mechanical and physical parameters assigned to the embankment body and foundation units according to advanced soil constitutive models are reported in [16].…”