UPCOMING LECTURES
Notices of upcoming technical lectures will be posted here.
PREVIOUS LECTURES
New Approaches for Evaluating the Seismic Performance of Slopes and Earth Dams
by Ellen M. Rathje, Ph.D., P.E., F.ASCE, Professor, Department of Civil, Architectural, and Environmental Engineering, University of Texas at Austin (UT). on Monday June 10th, 2024 at 1730
Seismic performance assessments for earth slopes and dams are based on evaluating the permanent displacements induced by earthquake shaking and more recently probabilistic approaches have been proposed to incorporate uncertainties into the analysis. This presentation will describe newly developed predictive models for earthquake-induced slope displacements based on finite element simulations. The models are developed using both classical regression techniques and artificial neural networks (ANN), and models for both the median displacement and its variability are provided. A missing part of most seismic performance assessments for slopes and dams is the translation of a displacement level into a damage state. This presentation will also outline a seismic fragility framework for earth dams and slopes that is modeled after the approaches used for other types of infrastructure, such as bridges. The framework uses an engineering demand model to predict the permanent displacement as a function of ground motion intensity, and a seismic capacity model to predict the probability of a damage state given the permanent settlement.
Debris flow mitigation with flexible barrier systems
by Andi Buechi, A.Sc.T., (Geobrugg North America, LLC) on Thursday April 25th, 2024 at 1730
Debris flow mitigation using flexible nets and barriers that have been installed in Western Canada over the past 20 years. Owners of highways, hydro dams, pipelines, railways and other infrastructure projects have increasingly relied upon and installed flexible mitigation systems to protect their assets. The systems require a very small footprint, both physically and environmentally, while providing a certified, adaptable, and engineered solution that can outperform more rigid engineered structures. There is an increased demand for these adaptable off the shelf systems to be installed after wildfires, due to increased frequency and intensity of rainstorms causing both debris flow and flood events.
Through the talk you will learn about how these mitigation systems were developed, how the systems are tested and certified, as well as the current state-of-the-art in this field of expertise. Case studies of different installations of early debris flow barriers protecting railways, towns, and highways through to more recent examples will also be presented. The case studies will cover recent post wildfire installations in the USA and Canada where the design and installation of the flexible barriers were conducted in environmentally sensitive areas. Slides will be shown of systems outlining some of the key sizing and design information such as the various heights, lengths, impact ratings and ground conditions. Designers, contractors and engineers will find tips and best practices for installing systems in different conditions such as soil, rock and talus.
Women in VGS: Inclusion in Action
The Vancouver Geotechnical Society was proud to host its first Women in VGS Event with a panel discussion on “Inclusion in Action” on Wednesday, April 10th, 2024. Seeing so many dynamic women (and allies!) coming together was inspiring!
Many thanks to the panel members for sharing their experience, which was inspiring, empowering, and most important - relatable!
Caroline Andrewes
María V. (Mavi) Sanín Blair
Susan Hollingshead
Carie-Ann Lau
Karen Savage
A thank you to our sponsors, BGC Engineering Inc., Ecora Engineering & Environmental, Klohn Crippen Berger, RAM, Stantec, Tetra Tech, Thurber Engineering Ltd., and WSP, for supporting this event.
UBC GeoRox Distinguished Lecture - WHY DAM FAILURES HAPPEN AND WHAT CAN WE DO ABOUT IT ?
by Dr. Violeta Martin, P.Eng. on Wednesday, 03rd April at ESB 1012, Earth Science Building, UBC
The safety of mining dams is being increasingly scrutinized by the public, investors, regulators, and engineering communities in the wake of recent catastrophic failures that resulted in loss of life and environmental damage. This talk will focus on dams and some of the hazards associated with dams. While it can be argued that a dam is a dam, and that every dam needs to satisfy the same safety criteria, specific considerations related to tailings dams are worthwhile discussing. Failure modes and mechanisms will be reviewed, along with recent advancements in evaluating the consequences of potential failures, which can be vastly different from failures of water dams. Understanding the consequences is critical because every life matters, the damage to the environment matters, and the loss of cultural and economic values matters. This knowledge can lead to design improvements and further advancements in risk mitigation measures, as well as the safe decommissioning of dams.
Geohazards from the november 2021 atmospheric river - learnings from indigenous and western science
by Carie-Ann Lau, M.Sc., P.Geo (BGC Engineering) and Rick McKamey (Willow Creek Environmental Services) , Thursday, March 14th, 2024 at 1730
The November 2021 atmospheric river caused more than 1,300 geohazards to be triggered in southern British Columbia. Many of these geohazards were sourced from watersheds that had experienced previous cumulative damages, such as wildfires, logging, and resource road construction. These geohazards were sources of sediment that entered mainstem rivers and contributed to flood and bank erosion damages to communities, infrastructure, and ecological systems. The geohazards and associated damages of the November 2021 atmospheric river are examples of cumulative watershed issues that Indigenous communities have long expressed concerns about. Watersheds draining into Leq’á:mel First Nation have been heavily logged and frequently produce sediment-laden flooding. During the November 2021 atmospheric river, Leq’á:mel experienced damages to critical ecological habitat, community infrastructure, and critical facilities. As we learn from the November 2021 atmospheric river and apply these learnings to resilient community planning, geotechnical practitioners can benefit from integrating Indigenous knowledge about geohazards and watershed management practices.
validation of computational liquefaction: 1974 tar island slump
by Michael G Jefferies, P.Eng, Thursday, February 8th, 2024 at 1730
Finite element analyses using critical state theory proved necessary to understand the development of static liquefaction during three recent large tailings dam failures at Fundao, Cadia and Brumadinho. However, the complexity of these events prevents them being viewed as a complete validation of the methodology - there are too many judgments over various aspects of each case history. Here we evaluate a far simpler case of static liquefaction: the 1974 Tar Island (Suncor, Alberta) slump, which involved a rapid drop of 5m during construction of a 12.5m high upstream raise over loose tailings. While not a dam stability issue, the event has the attraction of being load-induced, with simple geometry, and with known material properties and insitu state. The analyses were carried out with commercial software (PLAXIS) and use critical state theory with largely familiar soil properties measured by standard methods. The computed liquefaction develops from a prior drained condition, with essentially no precursors, before propagating rapidly undrained – there are similarities to the video record at Brumadinho and an animation will be shown to illustrate this. All aspects of the failure are replicated using properties as measured without "corrections", and in many ways this case history is a template for static liquefaction assessments. On a historical note, the theory and methodology were developed from construction in the Canadian arctic offshore 1982-9 by Gulf Canada Resources - this is very much a Canadian story, albeit one that is near fifty years old.
Rapid load testing: a useful alternative for foundation testing
by Marcel W. Bielefeld, MSc MScBA, Allnamics Geotechnical & Pile Testing Experts Thursday, February 1st, 2024 at 1730
Of all the foundation load test methods, Static Load Tests are considered the most reliable, but it is a long process, both for the construction of the reaction system and for the test itself. This means that static load tests have a high cost, and in addition the mobilization of the reaction elements often interferes with the site logistics. In the 1960s an alternative to static load tests was developed: the High Strain Dynamic Test, commonly referred to as a Dynamic Load Test. While this test method has advantages in terms of cost and test duration, these advantages are offset by a reduction in the accuracy of the results. In addition, the impact energy that must be applied to mobilize the test load can damage the foundation being tested. In the mid 1980s another alternative load test was developed, right here in Canada: the Rapid Load Test, whereby a load is applied to the foundation under quasi-static conditions. The first application was the so-called StatNamic test, which uses solid fuel to generate a downward force on the foundation. Given environmental and safety regulations in many countries around the world, the (transport of the) fuel for a StatNamic test can be problematic. As a result, alternate rapid load testing devices were developed that do not involve combustion, such as the StatRapid. In this presentation, Marcel Bielefeld will compare these foundation testing methods in more detail and demonstrate that Rapid Load Testing is not only a useful alternative for foundation testing but that, especially for larger foundation elements, this testing method deserves to be considered first.
Wings of Wisdom: Ignite Your Geotech Career – A Spicy Bash for Young Professionals
The VGS and CGS Young Professional (YP) committee jointly hosted "Wings of Wisdom: Ignite Your Geotech Career – A Spicy Bash for Young Professionals"; the event was a hot wings themed panel discussion for young professionals (geotechnical professionals with under 10 years of experience) and was held on Thursday, January 25th, 2024 at Steamworks Brewpub in Vancouver. Courageous panelists tackled a range of questions while taking on increasingly spicy hot wings for added excitement.
Based on the positive feedback from both panelists and attendees, we intend to organize future YP events!
Thank you again to our daring panelists and attendees for participating in the event:
Megan Atkinson, P.Eng from WSP
Jared Whitehead, M.Eng., P.Eng. from Kontur Geotechnical Consultants Inc.
Adam Woods, P. Eng. from Thurber Engineering Ltd.
Trevor Carey, P.Eng from the The University of British Columbia
Juliana Martin, P.Eng from WSP
Tunnelling in british columbia - a retrospective from 1880 to 2023
by Duncan Wyllie, M.SC., Ph.D, Wyllie and Norrish Rock Engineers, Thursday, January 11, 2024 at 1715 at the Steamworks Brewpub (Uber Room) 375 Water St., Vancouver.
Tunnels are an essential component of the British Columbia economy, for both civil infrastructure and mining operations. Regarding, civil tunnels, the first tunnels were probably driven in the 1880’s for the Canadian Pacific Railway and in the 140 years since then the total number of tunnels for all applications is about 260, most of which are still in operation. The majority of the tunnels are for transportation, power generation and water and sewer operations, but tunnels are also operated by organizations such as the Department of Fisheries and Oceans and the Trans Mountain Expansion Project pipeline.
The presentation will provide an overview of BC tunnels from early drill and blast operations to recent TBM projects. Tunnelling methods include drill and blast, road header, TBM, compressed air, sunken tube and lake taps, and the tunnels range from CP Rail’s 14.66 km long Mt. Macdonald tunnel, the longest tunnel in the western hemisphere, to a 1700 m long tunnel for Canada Post that was abandoned soon after it as put into use.
Observed geo-seismic impacts of the february 6th, 2023 turkiye earthquakes
by Tyler Southam, P.Eng. (Tetra Tech), and Thava Thavaraj, Ph.D., P.Eng. (KCB), Thursday, November 16, 2023 at 1730
On February 6th, 2023, a sequence of two damaging earthquakes with Mw7.8 and Mw7.7 occurred in southeastern Türkiye. The earthquakes resulted in over 50,000 fatalities and extensive damage over 11 provinces with economic losses estimated over $100 billion. Tyler and Thava were part of the Canadian Association of Earthquake Engineering (CAEE)’s reconnaissance team that toured the affected region to observe the impact of the earthquakes and record perishable data. In this talk, they will share their experience and observations focussing on the geo-seismic impacts of the earthquakes. The talk will start with a summary of the earthquake sequence and conclude with the lessons learned and drawing parallels to Southwestern BC. The geo-seismic impacts to be discussed will include ground motion amplification, ground rupture, liquefaction and strain softening, lateral spreading, liquefaction-induced displacements and settlements, rockfalls, and landslides. And These impacts have caused widespread damage to the infrastructure including buildings, bridges, earth dams, port structures, and lifelines.
Known knowns, known unknowns and unknown unknowns: Managing geotechnical risk using a combination of gbrS AND QUANTITATIVE RISK ANALYSIS
by Joe O’Carroll, P.E. - Senior Vice President at Mott MacDonald, Thursday, October 26, 2023 at 1730
Donald Rumsfeld's "known knowns, known unknowns and unknown unknowns" phrase resonates with geotechnical and tunneling engineers, probably as it sums up a problem that we face on every project, namely whether there is anything in the ground, and the way it behaves when we excavate and support it, that we know we just don’t know, and should be carrying contingency for in our project cost estimates. Avoiding claims for unforeseen ground conditions present owners and engineers with their greatest challenge, particularly on long linear underground infrastructure projects. This talk will look at how to manage geotechnical risk, and its associated cost impacts, using a combination of Geotechnical Baseline Reports (GBR) and Quantitative Risk Analysis (QRA).
helical piles: efficient foundation for static, dynamic, and seismic applications
by Hesham El Naggar, Ph.D., P.Eng., FCAE, FEIC, FASCE - Professor at the University of Western Ontario, Monday, October 16, 2023 at 1730
Helical piles have become popular foundation option owing to their many advantages related to ease of installation and large load carrying capacity. They are typically manufactured of straight steel shafts fitted with one or more helices and are installed using mechanical torque. They can sustain static and dynamic loading and are increasingly used in applications that induce complex loading conditions on them. The behavior and design of single vertical helical piles subjected to static loading is well investigated. However, the dynamic and seismic behavior of single helical piles and their group behavior are of great importance in modern foundation engineering practice but not yet well understood. This presentation presents recent advances in evaluating the axial and lateral capacity and performance of single and grouped helical piles and their response to static, dynamic and seismic loads.