Experimental and Numerical Investigations of a River Embankment Model under Transient Seepage Conditions

Roberta Ventini,Carmine Gerardo Gragnano,Marianna Pirone,Elena Dodaro,Daniela Giretti

doi:10.3390/geosciences11050192

Roberta Ventini, Carmine Gerardo Gragnano + Show 3 more

Open Access

https://doi.org/10.3390/geosciences11050192

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Abstract

The evaluation of riverbank stability often represents an underrated problem in engineering practice, but is also a topical geotechnical research issue. In fact, it is certainly true that soil water content and pore water pressure distributions in the riverbank materials vary with time, due to the changeable effects of hydrometric and climatic boundary conditions, strongly influencing the bank stability conditions. Nonetheless, the assessment of hydraulic and mechanical behavior of embankments are currently performed under the simplified hypothesis of steady-state seepage, generally neglecting the unsaturated soil related issues. In this paper, a comprehensive procedure for properly defining the key aspects of the problem is presented and, in particular, the soil characterization in partially saturated conditions of a suitably compacted mixture of sand and finer material, typical of flood embankments of the main river Po tributaries (Italy), is reported. The laboratory results have then been considered for modelling the embankment performance under transient seepage and following a set of possible hydrometric peaks. The outcome of the present contribution may provide meaningful geotechnical insights, for practitioners and researchers, in the flood risk assessment of river embankments.

Highlights

Riverbanks are passive defense works, consisting of earthen structures built along the edges of a stream or river channel to prevent flooding of the adjacent land
The factor of safety (FoS) associated to the steady-state regime investigated is just above one (1.05), which theoretically corresponds to an incipient condition of collapse
It should be noted that the analyses in steady state seepage conditions, though not being representative for the specific case, may provide useful information with regard to the existing margin of safety of the river embankment, as the related FoS might be identified with the reference threshold for a limit condition

Summary

Introduction

Riverbanks are passive defense works, consisting of earthen structures built along the edges of a stream or river channel to prevent flooding of the adjacent land. Index properties and initial suction of the TS70%-PON30% specimens compacted a6t othf 2e2 optimum Modified Proctor (γd dry unit weight, w natural water content, n soil porosity, e void ratio, Sr degree of saturation).

Results

Conclusion