Horizontal Translational Failures of Levees Due to Water Filled Gaps

A peat levee at Wilnis in The Netherlands suddenly failed at the end of the relatively dry summer of 2003. On Monday, 29 August 2005, Hurricane Katrina struck the U.S. gulf coast and breached, among other failures, the 17th Street Canal. These failures triggered large research programs. In the Wilnis case, it was eventually deduced that the 5-m horizontal translation of the levee was triggered by a combination of reduced weight by evaporation, shrinkage and cracking of the peat material, and an increased head in the sand layer under the dike. A key factor in the 17th Street Canal failure was the formation of a gap between the wall and the levee fill on the canal side of the fill. Due to climate change, more extreme dry and wet periods, land subsidence, and increasing sea and river levels, the horizontal shifting due to cracking is becoming more significant in the safety assessments of levees. In this paper, aspects of horizontal failures during extreme dry or wet periods are elaborated. First, a geo-hydrologic design procedure to assess the consequences of droughts for cracked peat levees is presented. The design procedure is then validated with measurements of a peat levee, the Middelburgsekade, and extreme water table positions that are likely to occur once in a period of 400 years that have been predicted for this levee. Furthermore, the most dangerous cracks for the Wilnis case are indicated. Next, the performance of levees and floodwalls during Hurricane Katrina are presented. Finally, the failure of the 17th Street Canal breach in New Orleans is described in detail. Conclusions are drawn related to horizontal failures and location of cracks during extreme weather condition

Lessons learned from dike failures in recent decades

The paper describes five different dike failures that occurred in recent decades. The case histories were located on different rivers and involved different loading conditions. The observed failure mechanisms involved erosion and stability problems. The types of erosion observed were both internal erosion due to extreme groundwater flow and external erosion caused by the river flow and wave action. The case involving instability was caused by uplift, i.e., increased hydraulic head led to a sharp reduction in maximum shear strength between subsoil layers. Two cases demonstrate the importance of dike management and maintenance. Despite the variations in the loading conditions and failure mechanisms, all the cases show that the strength of a dike depends not only on the material used to build the dike but also on the strength of the subsoil

Experimental and numerical investigations of dyke failures involving soft materials

This paper presents the results of an experimental and numerical investigation on the collapse of dykes involving soft soils. Nine centrifuge tests were carried out to investigate the dyke-subsoil interaction. The tests consisted in placing a dyke made out of Speswhite clay or Baskarp sand on a subsoil. The dykes and the subsoils were alternatively changed to explore the different contrast in stiffness ranging from stiff dykes on soft subsoil to soft dykes on stiff subsoils. The small scale models were placed in the centrifuge and were progressively accelerated up to a maximum of 100 G. The recordings, which were then processed by Particle Image Velocimetry (PIV), offered an insight onto the deformation and failure mechanisms. The results showed that dykes placed on a stiff subsoil underwent brittle failures with the development of slip surfaces whereas the same dyke placed on a soft subsoil underwent large deformation which presented a serviceability issue. These tests were then modelled with the Material Point Method (MPM), which is a continuum-based method for numerical simulation dedicated for large deformation problems. Simple constitutive models were used for which the parameters could be estimated using state indices.The authors acknowledge the Dutch Ministry of Public Works (Rijkswaterstaat-WVL) and the HHNK Water Authority for commissioning and financing the centrifuge tests. They would also like to thank the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement PIAP-GA-2012-324522 and the Swiss National Science Foundation under grant agreement P1SKP2 158621 for additional funding for the analysis of the data and the numerical modelling

Experimental and numerical investigations of dyke failures involving soft materials

This paper presents the results of an experimental and numerical investigation on the collapse of dykes involving soft soils. Nine centrifuge tests were carried out to investigate the dyke-subsoil interaction. The tests consisted in placing a dyke made out of Speswhite clay or Baskarp sand on a subsoil. The dykes and the subsoils were alternatively changed to explore the different contrast in stiffness ranging from stiff dykes on soft subsoil to soft dykes on stiff subsoils. The small scale models were placed in the centrifuge and were progressively accelerated up to a maximum of 100 G. The recordings, which were then processed by Particle Image Velocimetry (PIV), offered an insight onto the deformation and failure mechanisms. The results showed that dykes placed on a stiff subsoil underwent brittle failures with the development of slip surfaces whereas the same dyke placed on a soft subsoil underwent large deformation which presented a serviceability issue. These tests were then modelled with the Material Point Method (MPM), which is a continuum-based method for numerical simulation dedicated for large deformation problems. Simple constitutive models were used for which the parameters could be estimated using state indices.The authors acknowledge the Dutch Ministry of Public Works (Rijkswaterstaat-WVL) and the HHNK Water Authority for commissioning and financing the centrifuge tests. They would also like to thank the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement PIAP-GA-2012-324522 and the Swiss National Science Foundation under grant agreement P1SKP2 158621 for additional funding for the analysis of the data and the numerical modelling

Scénarios de ruptures complexes sur les digues

Levee breaches are often the result of a combination of mechanisms, which may happen simultaneously, and/or successively. These interactions are complex and difficult to anticipate in design and assessment as well as during a forensic analysis of an actual breach. The ISSMGE TC201 has published a report on the failure paths (that can also be called failure scenarios). It is available on the ISSMGE Onlline Library: https://www.issmge.org/online-library/reportsThe basis for this report is a compilation of case histories, and of failure paths used for assessment and design. Part A of the report provides an overview of the key concepts in this report and presents the proposed failure tree and overview of important aspects per event in the tree. The section finishes with a discussion and recommendations. Part B contains the collection of the contributed failure paths for case studies, these failure paths are illustrated in the framework. Part C contains the collection of contributed failure paths that are used for assessment and design. A glossary of key terms used is added at the end of the report

GEOLAB Material Properties Database

This papers includes soil properties of several physical modelling facilities included in the GEOLAB projectThe document contains the comprehensive &lsquo;one-stop&rsquo; material properties database developed by the GEOLAB consortium for the typical soils and constitutive models used in the GEOLAB facilities. The said database was developed to support the use and re-use of the quality experimental data from the GEOLAB Transnational Access projects.</p

Creep of geomaterials–some finding from the EU project CREEP

This paper gives a summary of some of the main findings of the EU founded project “Creep of geomaterials”, CREEP. CREEP was an Industry-Academia Partnerships and Pathways (IAPP) project funded from the 7th Framework Programme (FP7/2007–2013) of the EC under grant agreement PIAG-GA-2011-286397. The project aimed at establishing a consensus in creep modelling within geotechnical engineering. The materials studied were clay, peat and frozen soils (permafrost). Throughout the project, research on material behaviour in laboratory and field studies was combined with numerical studies using existing and newly developed mathematical frameworks. This paper summarises some of the findings in the project, although the focus is on the developments in the field of soft soils and soft clay in particular. The paper presents a unified enhanced soft clay creep model, which takes into account anisotropy, structure and rate dependency of the material. The performance of the model is demonstrated through analysis of the Murro test embankment. In addition, the paper gives an overview of some characteristics for frozen soil and peat. Some of the considerations regarding, e.g. over consolidation ratio for clay with respect to strain rate are very much valid for peat and frozen soil as well