Instability of flood embankments due to pore water pressure build-up at the toe : lesson learned from the Adige river case study

A case study is presented of the Adige River embankment, a segment of which experienced instability of the landside slope due to the development of uplift pressures. Soil profile and hydromechanical properties of the embankment and foundation materials have been assessed via site investigation, laboratory testing, and field monitoring for two cross sections, within and outside the failure segment. The hydromechanical model developed thereof was first validated against its ability to reproduce the probability of failure for the two sections with a first-order, second-moment (FOSM)-based approach. Comparison of water flow regimes between the two sections was then used to highlight the importance of the hydraulic properties of the material on the landside for the development of uplift pressures at the toe of the embankment. The lesson learnt from this case study is that the hydraulic response of the ground on the landside may play a critical role on the stability of flood embankments and its characterization should therefore not be overlooked when planning site investigation

Effect of partial saturation on the stability of shallow foundations above the water table

Granular ‘cohesionless’ soils above the water table are partially saturated but are commonly assumed to be dry in geotechnical practice. Accordingly, ‘drained’ shear strength is calculated by replacing the ‘saturated’ effective stress with the total stress. The ‘dry soil’ assumption neglects the effect t of suction on shear strength and, as a result, geo-structures are over designed. To investigate the implications of this assumption, this paper presents an approach to calculate the bearing capacity of shallow foundations above the water table taking into account the effects of partial saturation. This approach is based on the upper bound theorem of plasticity. The bearing capacity of a strip foundation in granular soils is calculated and the solution obtained by taking into account the effects of partial saturation is compared with the solution obtained from the classical ‘dry’ approach

Advances in the monitoring of geo-structure subjected to climate loading

The paper presents results achieved within the project MAGIC, a project funded by the European Commission under the Marie-Curie Industry Academia Partnerships and Pathways (IAPP) scheme. The project MAGIC aims to advance the state-of-the art in the monitoring of geo-structures subjected to climate loading by filling some of the gaps in current monitoring technologies. The project involves a partnership between academic and industrial partners to boost knowledge transfer and promote the development of ‘industrial’ instruments and services. The paper presents developments concerning the measurement of pore-water tension (suction in excess of 100 kPa) and the integration of geotechnical and geophysical monitoring

Lab at home : an innovative approach for online delivery of a practical civil engineering laboratory during the Covid-19 pandemic

The Covid-19 pandemic has forced many higher education institutions worldwide to suspend traditional face-to-face teaching and shift to online learning. This has presented many challenges for educators and students alike. In the engineering education sector, an important component of the curriculum is represented by practical, team-based activities such as laboratories and design projects. Laboratories provide an invaluable opportunity for engineering students to develop practical, problem-solving and team-working skills, in addition to deepen understanding of module-specific technical content. One of the main challenges to address during the Covid-19 pandemic and the sudden shift to online learning was therefore how to effectively transition these activities to an online format while preserving the quality of the learning experience and student engagement. This paper presents an innovative approach to deliver a practical team-based first year civil engineering laboratory in an online format. A carefully selected, small scale laboratory kit was delivered to students' homes, and the laboratory activity was redesigned to a certain extent in order to replace laboratory equipment with common household items. The approach includes the use of interactive videos, online quizzes, team meetings through video conferencing platforms. The paper reflects on the challenges and successes in the transition of the laboratory activity to the online format. The lessons learned from this experience can enhance student learning and inform strategies to improve the quality and effectiveness of online engineering education even after the Covid-19 pandemic

Probabilistic analysis of flood embankment stability: the case study of the Adige River embankment in Italy

Flooding is a worldwide phenomenon. Over the last few decades the world has experienced a rising number of devastating flood events and the trend in such natural disasters is increasing. Furthermore, escalations in both the probability and magnitude of flood hazards are expected as a result of climate change. Flood defence embankments are one of the major flood defence measures and stability assessment for these structures is therefore a very important process. Traditional deterministic approaches to stability analysis do not allow taking into account and quantifying the uncertainties in soil characterisation. For this reason they may not be sufficient to capture the failure of flood embankments. The paper presents a probabilistic approach for the stability analysis of flood embankments taking into account the probabilistic distribution of soil hydro-mechanical properties. The approach is validated against the failure case study of the Adige river embankment in Italy, by comparing the probability of failure of two sections, within and outside the failure segment respectively

Reliability analysis of flood embankments taking into account a stochastic distribution of hydraulic loading

Flooding is a worldwide phenomenon. Over the last few decades the world has experienced a rising number of devastating flood events and the trend in such natural disasters is increasing. Furthermore, escalations in both the probability and magnitude of flood hazards are expected as a result of climate change. Flood defence embankments are one of the major flood defence measures and reliability assessment for these structures is therefore a very important process. Routine hydro-mechanical models for the stability of flood embankments are based on the assumptions of steady-state through-flow and zero pore-pressures above the phreatic surface, i.e. negative capillary pressure (suction) is ignored. Despite common belief, these assumptions may not always lead to conservative design. In addition, hydraulic loading is stochastic in nature and flood embankment stability should therefore be assessed in probabilistic terms. This cannot be accommodated by steady-state flow models. The paper presents an approach for reliability analysis of flood embankment taking into account the transient water through-flow. The factor of safety of the embankment is assessed in probabilistic terms based on a stochastic distribution for the hydraulic loading. Two different probabilistic approaches are tested to compare and validate the results

Reliability analysis of flood embankments taking into account a stochastic distribution of hydraulic loading

Flooding is a worldwide phenomenon. Over the last few decades the world has experienced a rising number of devastating flood events and the trend in such natural disasters is increasing. Furthermore, escalations in both the probability and magnitude of flood hazards are expected as a result of climate change. Flood defence embankments are one of the major flood defence measures and reliability assessment for these structures is therefore a very important process. Routine hydro-mechanical models for the stability of flood embankments are based on the assumptions of steady-state through-flow and zero pore-pressures above the phreatic surface, i.e. negative capillary pressure (suction) is ignored. Despite common belief, these assumptions may not always lead to conservative design. In addition, hydraulic loading is stochastic in nature and flood embankment stability should therefore be assessed in probabilistic terms. This cannot be accommodated by steady-state flow models. The paper presents an approach for reliability analysis of flood embankment taking into account the transient water through-flow. The factor of safety of the embankment is assessed in probabilistic terms based on a stochastic distribution for the hydraulic loading. Two different probabilistic approaches are tested to compare and validate the results