Sixty Years Experience in Internal Erosion and Piping of Embankment Dams and their Foundations.
Early career.
I began my Dams career in 1962 and 1963 with university vacation practice at Sirinumu Dam, Papua New Guinea. The Main Dam is Steel Faced Rockfill, the Stage 1 Saddle Dams homogeneous earthfill founded on 30m of extremely weathered volcanic agglomerate which is lateritised.
My first job in 1966 with Commonwealth Department of Works after completing my Civil Engineering degree and an M. Eng. Sc. at University of Queensland was to design the raising of the seven Sirinumu Saddle Dams.
I was aware that good dam practice required that seepage through the dam and the foundations should be collected in filters so “piping” would not occur. The mechanics of piping were not understood but the principle was a good one and still is.
My mistake was that I assumed that the seepage through the embankments would be collected in a horizontal drain, as would seepage through the foundation, so no chimney drain was provided. This was based on (hand drawn) seepage flow nets in which I assumed vertical and horizontal permeability were equal. On raising the reservoir seepage emerged on the downstream slope consistent with KH / KV = 100. The resulting pore pressures meant that the downstream slopes had low factors of safety, and seepage was emerging unfiltered, so filter and berms had to be added!
In the early 1980’s while working for Coffey Partners I was the lead designer for the proposed Lungga Dam in the Solomon Islands. The dam site has karst limestone abutments and 50m of interbedded liquefiable sand and gravel in the foundation. Estimated seepage underflow even with a partially penetrating cutoff was 5 cumec (5000 litres / second). This required a three-stage horizontal filter drain which raised my awareness of filter criteria. The dam has never been constructed due to the challenging conditions and small power output compared to the cost.
In my nine years with Comworks and a total of ten years with Coffey and Hollingsworth and Coffey Partners I worked on about 40 dam projects, mostly new hydropower and water storage dams, and tailings dams. I also worked on many landslides with Coffey’s and my Comworks dams in PNG had landslide issues.
In all I have been involved in over 150 dams with another ≈ 100 dam risk assessments. This has involved dams throughout Australia, and in PNG, Thailand, Fiji, New Zealand, USA, Canada and Panama.
One benefit of working on many dams and landslides is that I have experienced a wide range of geological conditions and have developed a good understanding of engineering geology related to dams and landslides, ie the “geo” in geotechnical.
At UNSW, Landslide Risk Assessment and Courses on Geotechnical Engineering of Embankment Dams
When I joined UNSW in 1985 as Professor of Geotechnical Engineering I began to get involved in peer review consulting, initially regarding landslides, then dams.
I had become involved in landslide risk assessment in the early 1990’s (Fell, 1994) and was involved in the development of the general principles and guidelines for assessment of the risk posed by single slopes and for zoning of susceptibility, hazard and risk with the Australian Geomechanics Society and JTC 1, the joint ISSMGE, IAG, ISSRM Committee on landslides which I chaired for three years. (Fell et al, 2008).
I developed an M. Eng. Sc. Subject on geotechnical engineering of Embankment Dams and with my Engineering Geology colleagues David Stapledon and Patrick MacGregor gave several one-week courses covering this subject. They were each attended by up to 50 engineers and engineering geologists from industry.
The course notes were developed into the book Fell, R., MacGregor, J.P. and Stapledon, D.H. (1992). Geotechnical Engineering of Embankment Dams.
Early Development of Methods for Estimating the Likelihood of Failure by Internal Erosion and Piping.
At about the same time the ANCOLD (1994) Guidelines for Risk Assessment was developed. This included consultation and meetings with dam engineers from Canada, USA and Europe which I attended. I was involved in early risk assessments for dams. These assessments were quite rudimentary by today’s standards.
Most risk assessments are for existing dams, and it became apparent that many embankment dams have filters which do not meet modern design criteria and / or do not extend above full supply level (or above a seepage flow net level for reservoir at FSL), and often have excessive fines content so potentially hold a crack and would be ineffective as a filter.
I sought and obtained funding from ARC and seventeen dam owners and consultants to fund research into internal erosion and piping and filter criteria. This work was carried out by Dr Mark Foster for his PhD. There were also funds to support Dr Kurt Douglas who studied the statistics of concrete dam failures and the shear strength of rockfill. Australian owners, USBR, BC Hydro and Norwegian Geotechnical Institute provided access to case data. This began a long working relationship with USBR facilitated by Dr John Smart, later by John Cyganiewicz.
There were three important outputs from this work:
Foster et al (2000a, b) which covers the statistics of embankment dam failures and a method for assessing the relative likelihood of failure of embankment dams by piping based on these statistics.
Foster and Fell (1999) which describes a Framework for Estimating the Probability of Failure of Embankment Dams by Piping Using Event Tree Methods. This framework remains the basis for risk analyses.
Foster and Fell (2001), “Assessing embankment dams, filters which do not satisfy design criteria”. This forms the basis for assessing filters in existing dams and categorises them into no erosion, some erosion, excessive erosion and continuing erosion. No erosion filters satisfy modern filter criteria. For some and excessive erosion the filter will eventually seal but with significant leakage flows before sealing. These flows were later better documented in Foster et al (2018). Continuing erosion filters do not seal, and flows continue to increase.
We realized that the Foster et al (2000a, b) method does not adequately allow for the details of individual dams and advocated the use of event tree methods. These were used in risk assessments at that time.
Research into Large Landslides and Deformation of Dams.
Following the work above, I obtained funding from ARC and 21 dam owners and consultants to fund research into the pre and post failure performance of large landslides, the deformation behavior of embankment dams, and the performance of concrete face rockfill dams. This was carried out by Dr Gavan Hunter and Dr James Glastonbury. The large landslide study was motivated by the Vaiont Slide in Italy, and the presence of large landslides around the reservoir of some Australian Dams.
Relating to risk assessment for dams the outputs are described in Hunter and Fell (2003, 2003a) and Glastonbury and Fell (2002a, b; 2008a, b; 2010) and Fell et al (2007).
About this time Steven Pells gathered data on deformations and cracking of embankment dams during earthquakes. This is reported in Pells and Fell (2003).
Further Development of Methods for Estimating the Likelihood of Failure by Internal Erosion and Piping
It was becoming apparent that it was important to better model the mechanics of internal erosion rather than relying on statistics of dam performance. Funding from nineteen dam owners and consultants was obtained to support Dr Chi Fai Wan in his PhD studies. He made two important contributions:
Wan and Fell (2002, 2004) Development of the Hole Erosion Test to measure the critical shear stress of soil and the rate of erosion. The hydraulic shear stresses in vertical cracks in the core of dams were related to these to assess whether erosion would initiate.
Wan and Fell (2008) which presents a method for assessing whether silt sand gravel soils are subject to suffusion.
This funding also supported post-doctoral work by Dr Hong Bui for numerical modelling of the potential for cracking in embankment dams resulting from the deformations during construction.
These analyses were reported in Bui et al (2004, 2005) and formed the basis for the prediction of crack depth and width in the 2008 “Piping Toolbox” described below.
In 2004 the knowledge gained from these research projects, research elsewhere and experience in carrying out risk assessments on dams was consolidated to produce the UNICIV reports:
Fell, R. Wan CF and Foster M (2004) Methods for estimating the probability of failure of embankment dams by internal erosion and piping-piping through the embankment, and
Fell, R. and Wan CF (2005) Methods for estimating the probability of failure of embankment dams by internal erosion and piping in the foundation and from embankment to foundation.
These relied on the historic statistics of failures and accidents as “anchors” to the estimates but used event tree methods. Tables of aids to judgement were provided.
Failure in the embankment was for concentrated leak erosion relating to cracking during construction, poorly compacted zones around conduits and near walls, desiccation cracking.
Failure in the foundation was for backward erosion piping, suffusion, and concentrated leak erosion in cracks.
These documents were the basis upon which the 2008 Piping Toolbox was developed.
It was about this time that we published “Fell, R., Macgregor, J.P., Stapledon, D. and Bell, G. (2005). Geotechnical Engineering of Dams”. This covered the foundations for concrete dams as well as embankment dams and their foundations.
Development of the 2008 Piping Toolbox.
During the period July 2005 to August 2008, a Development Team with representatives from the United States Department of the Interior, Bureau of Reclamation (Reclamation), the United States Army Corps of Engineers (USACE), URS (now AECOM), and the University of New South Wales, Sydney, developed a methodology for performing quantitative risk analysis for internal erosion and piping failure modes for embankment dams.
This resulted in the document “Risk Analysis for Dam Safety, A Unified Method for Estimating Probabilities of Failure of Embankment Dams by Internal erosion and Piping” which was issued as a Delta Version, in August 2008. That document has been referred to as the “Piping Toolbox” and has been used extensively in Australia for risk analyses for embankment dams, flood retention basin embankments, levees, canals and their foundations. It has been used as a reference document by Reclamation and USACE for risk analyses for their dams and levees within their “Best Practices in Dam and Levee Safety Risk Analysis” which is a joint publication by Reclamation and USACE.
Within this document the 2008 document is referred to Fell et al (2008) or the 2008 Piping Toolbox.
The motivation for developing the Toolbox was that USACE were about to undertake QRA for their > 400 dams and wanted a more prescriptive approach so assessments would be more consistent than was achieved using methods like those in Fell et al (2004) and Fell and Wan (2005).
The estimates of the annual probability of initiation of erosion were anchored to historic performance for each potential failure mode. The estimates of conditional probability were based on the mechanics of erosion, the factors affecting the quantification, and the expert judgement of the development team. The methods were trialled before issuing the document.
On-going Research into Internal Erosion and Piping.
Since the development of the 2008 Toolbox there has been extensive research carried out in Europe, USA, Canada and Australia into the mechanics of internal erosion including concentrated leak erosion, backward erosion piping, suffusion, global backward erosion and contact erosion.
Much of this has centred around backward erosion piping with main contributions from Deltares Netherlands, and USACE; Suffusion and GBE at University of British Columbia, Nantes University, France and Luleå University Sweden; and Contact Erosion at Grenoble University, France.
Much credit for the research activity is due to Dr Jean-Jacques Fry who was with Electricite’ de France. He was instrumental in establishing the European Working Group on Internal Erosion (EWGIE) and for supporting research on the topic. The group meets annually and have welcomed input from Canada, USA, Australia and New Zealand as well Europe.
Research at UNSW was funded by ARC and thirteen owners and consultants and consisted of four components:
Dr Ke He, studying under the direction of Professor Chongmin Song, on numerical modelling of cracking resulting from deformations during and post construction. This included development of methods to model crack propagation. This is reported in He et al (2019, 2021).
Dr Rebecca Allan studying under the direction of Dr Kurt Douglas and Adjunct Professor Bill Peirson, on aspects of Backward Erosion Piping including the effect of exit conditions on initiation and progression of erosion and testing of silt sand soils. This is reported in Allan (2018).
Dr Steven Pells studying under the direction of Adjunct Professor Bill Peirson and Dr Kurt Douglas, on erosion of unlined spillways in rock. This is reported in Pells et al (2016) and Douglas et al (2018).
Dr Kurt Douglas and I, with Hamish Studholme and Bill Peirson on Suffusion and GBE. This is reported in Douglas et al, (2019).
In addition to this were:
Steven Savage supervised by Dr Kurt Douglas on modelling of the swelling of the soil in the sides of cracks, reported in Savage et al (2019) and
Adjunct Professor Bill Peirson and V. Prapakaran on modelling of flow in narrow vertical cracks in dam cores reported in Peirson et al (2022) and flow in narrow cracks in confined flow reported in Peirson and Fell (2024).
Development of ICOLD Bulletin 164 Internal Erosion of Existing Dams, Levees, Dikes and their Foundations.
Over the period from 2010 to 2014 I worked with Jean-Jacques Fry and Rodney Bridle to draft ICOLD Bulletin 164. This incorporated the results of research and state of practice up to that time.
Concurrently I and my co-authors drafted, Fell, R., MacGregor; P, Stapledon, D., Bell, G, and Foster, M. (2015) Geotechnical Engineering of Dams, Second edition.
Development of the 2024 Piping Toolbox
It was recognised that the 2008 Toolbox was out of date and needed to be updated to reflect advances in understanding the mechanics of internal erosion and piping.
Five members of the original development team worked to update the document. The work was done independently of Reclamation and USACE. The sixth member, Noah Vroman, was unable to contribute as he holds the position of Director of the Dam and Levee Safety Production Center, USACE.
As for the 2008 Toolbox the estimates of the annual probability of initiation of erosion are anchored to historic performance for each potential failure mode. The conditional probability estimates are then based on the mechanics of erosion, the factors affecting the quantification, and the expert judgement of the development team.
The 2024 Toolbox was issued in September 2024 as Fell et al (2024) and supersedes the 2008 Toolbox. It is available to all at https://www.unsw.edu.au/engineering/our-schools/civil-and-environmental-engineering/our-research/uniciv-reports
The 2024 Toolbox has a very detailed supporting document which all users should read to understand the background and limitations of the methods in the Guidance Document.
Some other Research Projects.
This document is about internal erosion and piping, but I want to acknowledge my other PhD students. These are Jwo Ran (Jerry) Chen embankments on soft soils; Gareth Swarbrick, desiccation of mine tailings; Fiona MacGregor, rippability of rock, and Peter Finlay, aspects of landslide risk analyses and assessment.
Some Comments on the State of Practice.
The following are some comments on the State of Practice of the understanding of the mechanics of internal erosion and piping:
Concentrated leak erosion.
The work by Ke He showed that cracking is mostly controlled by post construction settlements of the embankment and its foundations. Cross valley numerical analyses coupled with crack propagation analyses give a reasonable understanding of the strain localisation and the potential depth of cracking. However, there are only a few case data to calibrate these analyses. There is some indication that rather than a single crack forming as the modelling assumes the extensional strains resulting from post construction settlement are likely to be distributed to form several narrower cracks. This is less so for earthquake induced settlements.
The work by Bill Peirson has shown that the hydraulic shear stresses at the downstream end of narrow vertical cracks with no downstream control such as a filter, are significantly higher than the 2008 Toolbox had assumed. As a result, the likelihood of initiation of erosion with no downstream control is higher than estimated by the method in the 2008 Toolbox and reported in ICOLD Bulletin 164 and Fell et al (2015). However, the hydraulic shear stresses are lower at the upstream end and for some soils cracks less than 2 to 5mm width are likely to close by swelling.
For the 2024 Toolbox an approximate method has been adopted to model the effect of downstream filters. These potentially reduce the hydraulic shear stresses to around or less than the 2008 Toolbox method.
More research is required to quantify the effect of downstream filters or transition zones on these hydraulic stresses and on the time dependency of swelling.
Backward Erosion Piping.
There has been extensive research carried out which is summarized in the 2024 Toolbox Supporting Document. Progress has been achieved in understanding the mechanics but there is still considerable uncertainty in the methods for predicting the progression of BEP. This is in part due to most experiments being at small scale and the results requiring scaling factors to be applied to be applicable to field scale. More full-scale case data is required, but that is difficult and expensive to obtain. It may be possible to better understand the scale effects with advanced 3D numerical modelling. In the meantime, that uncertainty needs to be accounted for, and has been in the 2024 Toolbox.
Suffusion and Global Backward Erosion.
Suffusion is a mechanism which applies to non-plastic silt sand gravel soils which are gap graded or are broadly graded but with a gradation which precludes self-filtering. The finer fraction fits within the voids between the coarse fraction, that is the voids are under-filled. Unfortunately, the term suffusion has also been used in some literature to describe internal instability in soils which are not in fact subject to suffusion. To further confuse the issue some have used the term suffosion to describe silt sand gravel soils where volume change occurs with erosion of particles from the soil. Earlier literature used the term suffosion to describe suffusion.
In Fell and Fry (2007) we introduced the term Global Backward Erosion to describe erosion of non-plastic silt sand gravel soils where the voids are over-filled, so the coarse particles are supported by the finer fraction.
The testing reported in Douglas et al, (2019) demonstrated that there is not a clear distinction between soils subject to suffusion and GBE. Rather there is a spectrum of behavior with different effects on the amount and rate of erosion. All the Douglas et al (2019) tests were downward flow whereas in practice flow is mostly horizontal and we did not attempt to apply confining stress as that complicates the test set up. There is evidence that internal movement of soil particles occurs so for longer erosion paths the soil may be more likely to develop self-filtering when that was not the case for our 400mm thick test samples. Despite this we feel this approach is the best available
There is a lot of research being carried out elsewhere, some of which I get to review for Journals. Much relies on testing by others without regard for differences in test set-up. A few are doing high quality laboratory testing but mostly on finer soils. Unfortunately, new “theories” are sometimes proposed based on only a few tests.
Others are trying to model this behavior using numerical Discrete Element Models. While this may be academically attractive, and cheaper than laboratory testing, I see little practical use of such research. In my opinion laboratory tests are essential to understand the complex mechanisms involved.
Contact Erosion.
There are two mechanisms involved:
The methods for assessing the former are well based for non-plastic soils but not so well for plastic soils. The 2024 Toolbox uses hydraulic shear stresses from a published source and relates them to the critical shear stress of the soil. This mechanism warrants more research.
The mechanics of the second mechanism are well established as the erosion is related to the hydraulic shear stress in the joint which can be assessed using the 2008 Toolbox approach. For erosion to occur the joint or defect in the rock must persist from upstream to downstream of the dam. I have seen excessively conservative assessments of this, particularly for narrow cracks, eg. 1 to 2mm, which are unlikely to be persistent, and likely to close under the stress imposed on the foundation by the dam.
The need to “anchor” estimates to historic data.
As discussed above the 2024 Toolbox anchors the estimates of initiation of concentrated leak erosion on historic data. We see this as necessary because we are not able to confidently predict the presence, persistence, depth and width of cracks, even with the best numerical modelling.
With more case data, including mapping of cracking during dam upgrades it may be possible to stop using this approach. Such careful mapping of cracking should be the norm in all upgrades.
ALARP as being applied to assessing dam upgrades.
Recently there has been a greater emphasis on achieving ALARP when designing dam upgrades than was the case some years ago. I have a few comments:
Observations on the Dam Profession as a Peer Reviewer.
There are many capable and committed persons involved in dam engineering in Australia and this is not to criticize them. I do however have some concerns based on my experience as a Peer Reviewer. These include:
The limited adoption of Quantitative Risk Assessment.
QRA as practiced in Australia, Reclamation and USACE has not been widely accepted. Other Federal Government Agencies in USA are gradually working towards QRA but have not despite Reclamation having done so since the 1990’s. Feedback from draft of the 2024 Toolbox indicates some are using QRA in UK, South America and South Africa.
In some cases, in Canada and USA, the process has been bogged down by too great an emphasis on uncertainty and defensibility of estimates. In some countries in Europe the legal framework makes adoption of QRA difficult.
The outcomes for QRA of internal erosion and piping are still semi-empirical being anchored to historic data. They are better at assessing relative likelihood of failure than absolute annual probabilities of failure. They do, however, form a logical and defensible approach to assessing dam safety and the needs for upgrades. They have served the Australian Dam community well, and from my experience, USACE and Reclamation too.
In recognition of the reluctance to adopt QRA, I along with Mark Foster, Gavan Hunter and Chi Fai Wan are writing a book “Assessing the Safety of Existing Embankment Dams” to be published by Taylor Francis late in 2025. It will cover QRA, semi-quantitative QRA and “standards based’ approaches. It will cover Internal Erosion and Piping, Slope Instability and Overtopping failure modes.
Good Design Practice relating to Internal Erosion and Piping.
Good design practice has changed somewhat since I began work in 1966.
Acknowledgements
In my early career with Comworks I was fortunate to have worked under John Fraser, who gave me a lot of responsibility and exposure to challenging projects. I was even more fortunate to be appointed as Professor of Geotechnical Engineering at UNSW. This opening the door to rubbing shoulders with leading experts in landslides and dams in Australia and Internationally, and to my peer review work and research. I have been able to focus this research to issues arising from my experience and peer review work for many dam owners in Australia, USA, Canada and Panama.
REFERENCES IN CHRONOLOGICAL ORDER
Fell, R., MacGregor, J.P. and Stapledon, D.H. (1992). Geotechnical Engineering of Embankment Dams, Balkema.
Fell, R. (1994). Landslide risk assessment and acceptable risk. Canadian Geotechnical Journal, Vol 31, 261-272.
Foster, M., Spannagle, M. and Fell, R. (1998). Report on the Analysis of Embankment Dam Incidents. UNICIV Report No. R374, School of Civil and Environmental Engineering, University of New South Wales ISBN: 85841 349 3; ISSN 0077-880X.
Foster, M.A. and Fell, R. (1999a). Assessing Embankment Dam Filters Which Do Not Satisfy Design Criteria. UNICIV Report No. R-376, School of Civil and Environmental Engineering, University of New South Wales. ISBN: 85841 343 4, ISSN 0077-880X.
Foster, M.A. and Fell, R. (1999b). A Framework for Estimating the Probability of Failure of Embankment Dams by Piping Using Event Tree Methods. UNICIV Report No. R377. School of Civil and Environmental Engineering, The University of New South Wales. ISBN 85841 343 4.
Foster, M., Fell, R. and Spannagle, M. (2000a). The statistics of embankment dam failures and accidents, Canadian Geotechnical Journal, Vol.37, No.5, National Research Council Canada, Ottawa, pp.1000-1024, ISSN: 0008-3674.
Foster, M., Fell, R. and Spannagle, M. (2000b). A method for assessing the relative likelihood of failure of embankment dams by piping, Canadian Geotechnical Journal, Vol.37, No.5, National Research Council Canada, Ottawa, pp.1025-1062, ISSN: 0008-3674.
Foster, M. and Fell, R. (2001). Assessing embankment dams, filters which do not satisfy design criteria, J. Geotechnical and Geoenvironmental Engineering, ASCE, Vol.127, No.4, May 2001, 398-407.
Glastonbury, J. and Fell, R. (2002). Report on the Analysis of the Deformation Behaviour of Excavated Rock Slopes. UNICIV Report No. R-403, ISBN 85841 370 1. School of Civil and Environmental Engineering, The University of New South Wales.
Glastonbury, J., Fell, R. and Mostyn, G. (2002a). Report on the Post Collapse Behaviour of Debris from Rock Slope Failures. UNICIV Report R-406, ISBN 85841 373 6, School of Civil and Environmental Engineering, The University of New South Wales.
Glastonbury, J. and Fell, R. (2002b). A Decision Analysis Framework for Assessing Post-Failure Velocity of Natural Rock Slopes. UNICIV Report No. R-409, ISBN: 85841 376 0. School of Civil and Environmental Engineering, The University of New South Wales.
Wan, C.F. and Fell, R. (2002). Investigation of internal erosion and piping of soils in embankment dams by the slot erosion test and the hole erosion test. UNICIV Report No. R-412, ISBN: 85841 379 5, School of Civil and Environmental Engineering, The University of New South Wales.
Hunter, G. and Fell, R. (2003a). Rockfill modulus and settlement of concrete face rockfill dams. ASCE Journal of Geotechnical and GeoEnvironmental Engineering, American Society of Civil Engineers, Vol.129, No.10, pp.909-917, American Society of Civil Engineers, Relston, USA, ISSN 1090-0241.
Hunter, G. and Fell, R. (2003b). The Deformation Behaviour of Embankment Dams. UNICIV Report No. R-416, ISBN 85841 383 3, School of Civil and Environmental Engineering, The University of New South Wales.
Pells, S. and Fell, R. (2003). Damage and cracking of embankment dams by earthquake and the implications for internal erosion and piping. The 21st Congress, International Commission on Large Dams, Montreal.
Bui, H., Fell, R. and Song, C. (2004). Two and three dimensional numerical modelling of the potential for cracking of embankment dams during construction. UNICIV Report No. 426, The School of Civil and Environmental Engineering, The University of New South Wales, Sydney. www.engineering.unsw.edu.au/civil-engineering/uniciv-reports
Bui, H., Tandrijana, V., Fell, R. Song, C. and Khalili, N. (2005). Two and three dimensional numerical modeling of the potential for cracking of embankment dams-supplementary report UNICIV Report No. 438, The School of Civil and Environmental Engineering, The University of New South Wales, Sydney. www.engineering.unsw.edu.au/civil-engineering/uniciv-reports
Wan, C.F. and Fell, R. (2004). Investigation of rate of erosion of soils in embankment dams. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol.130, No.4, 373-380.
Fell, R. Wan CF and Foster M (2004) Methods for estimating the probability of failure of embankment dams by internal erosion and piping-piping through the embankment. UNICIV Report No R 428, The University of New South Wales, ISBN 85841 395 7
Fell, R. and Wan CF (2005) Methods for estimating the probability of failure of embankment dams by internal erosion and piping in the foundation and from embankment to foundation. UNICIV Report No R 436, The University of New South Wales. ISBN 85841 403 1
Fell, R., Macgregor, J.P., Stapledon, D. and Bell, G. (2005). Geotechnical Engineering of Dams, Balkema.
Fell, R. and Fry, J.J. (2007). The state of the art of assessing the likelihood of internal erosion of embankment dams, water retaining structures and their foundations. In Internal Erosion of Dams and their Foundations. Editors R. Fell and J.J Fry. Taylor and Francis, London. 1-24.
Fell, R. (2007) The mechanics of internal erosion and piping of embankment dams and their foundations. John Jaeger Memorial Lecture. In Proceedings of the 10th Australia New Zealand Conference on Geomechanics, Volume 1, 60-95. Editors J Ameratunga, B Taylor and M Patten. Australian Geomechanics Society, ISBN 978-0-646-47974-3.
Fell, R., Glastonbury, J. and Hunter, G. (2007) Rapid landslides: the importance of understanding mechanisms and rupture surface mechanics. The eighth Glossop Lecture. Quarterly Journal of Engineering Geology and Hydrology, 40, 9-27.
Fell, R., Corominas, J., Bonnard, C., Cascini, L., Leroi, E., and Savage, W. (2008) Guidelines for landslide susceptibility, hazard and risk zoning for land use planning. Engineering Geology, 102, 85-98.
Glastonbury, J. and Fell, R. (2008a). A decision analysis framework for the assessment of likely post failure velocity of translational and compound natural rock slope landslides. Canadian Geotechnical Journal, Vol 45, No 3, 329-350.
Glastonbury, J.P. and Fell, R. (2008b). The geotechnical characteristics of large slow, very slow and extremely slow landslides. Canadian Geotechnical Journal, Vol 45, No 7, 984-1005.
Wan. C.F., and Fell, R. (2008) Assessing the Potential of Internal erosion and Suffusion in Embankment Dams and Their Foundations. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol 134, No3, 410-407.
Fell, R., Foster, M.A., Cyganiewicz, J., Sills, G., Vroman, N. and Davidson, R. (2008) A Unified Method for Estimating Probabilities of Failure of Embankment Dams by Internal erosion and Piping. UNICIV Report No R 446, The School of Civil and Environmental Engineering, University of New South Wales, Sydney.
Glastonbury, J.P. and Fell, R. (2010) Geotechnical characteristics of large rapid landslides, Canadian Geotechnical Journal, Vol. 47, No 1, 116-132.
Fell, R., MacGregor; P, Stapledon, D., Bell, G, and Foster, M. (2015) Geotechnical Engineering of Dams, Second edition. Taylor Francis Group, London.
Pells, S.E., Douglas, K., Pells, P.J.N., Fell, R., Peirson, W.L., (2016). Rock Mass Erodibility. Journal of Hydraulic Engineering 06016031. doi:10.1061/(ASCE)HY.1943-7900.0001243.
Douglas, K.J., Fell, R., Peirson, W.L., and Studholme, H. (2017) Experimental Investigation of Global Backward Erosion and Suffusion. UNICIV Report No. R465. School of Civil and Environmental Engineering, UNSW. ISBN: 0-7334-3719-2
He, K., Fell, R. and Song, C. (2017). Stresses and Strains in Embankment Dams Resulting from Differential; Settlements. UNICIV Report No. R-466, School of Civil and Environmental Engineering, University of New South Wales, Sydney, Australia. ISBN: 978-0-7334-3773-1. www.engineering.unsw.edu.au/civil-engineering/uniciv-reports
Allan, R.J. (2018) Backward Erosion Piping. PhD thesis, School of Civil and Environmental Engineering, University of New South Wales.
Foster. M., Ronnqvist, H. and Fell, R. (2018). The performance of embankment dams with filters coarser than ‘no-erosion’ design criteria. Hydropower and Dams, Issue Four, 64-71
Douglas, K.D., Pells, S., Fell, R. and Peirson, B. (2018). The influence of geological conditions on erosion of unlined spillways in rock. Quarterly Journal of Engineering Geology and Hydrogeology, Vol.51, 219-228
Douglas, K.J., Fell, R., Peirson, W.L., and Studholme, H. (2019) Experimental Investigation of Global Backward Erosion and Suffusion. Canadian Geotechnical Journal 56, 789-807.
Savage, S., Douglas, K., Fell, R., Peirson, W and Berndt, R. (2019) Modelling the Erosion and Swelling of the sides of Transverse Cracks in Embankment dams. J. ASCE. Geotech, Geoenvironmental Eng. 145(5) 04019015.
He, K., Fell, R. and Song, C. (2019). Transverse Cracking in Embankment Dams Resulting from Cross Valley Differential Settlements. European Journal of Environmental and Civil Engineering, DOI: 10.1080/19648189.2019.1691663
He, K., Song, C. and Fell, R. (2021). Numerical modelling of transverse cracking in embankment dams. Computers and Geotechnics, doi.org/10.1016/j.compgeo.2021.104028
Peirson W.L., Prapakaran, V., Fell. R. and Douglas, K. (2022) On the hydraulics of flow in cracks in embankment dam cores. European Journal of Environmental and Civil Engineering.DOI:10.1080/19648189.2022.20811993.
Peirson, W.L. and Fell, R. (2024) Pressurised Flow in Cracks in Embankment Dam Cores. Accepted for publication in European Journal of Environmental and Civil Engineering.
Fell, R., Foster, M.A., Cyganiewicz, J., Sills, G. and Davidson, R. (2024). Methods for Estimating the Probability of Failure of Embankment Dams by Internal Erosion and Piping. UNICIV Report No. R470, The School of Civil and Environmental Engineering, University of New South Wales, Sydney.
ANCOLD is an incorporated voluntary association of organisations and individual professionals with an interest in dams in Australia.
System maintenance will be performed on the servers that host the ANCOLD Digital Guidelines, on Saturday, December 21st @ 10:00 PM AEDT which will require the servers to reboot.
Total downtime during that event could be up to 4 hours and will commence sharply at 10 pm AEDT. During that time end users will not be able to view or access their secured content.
