Lessons Learned for Ground Movements and Soil Stabilization from The Boston Central Artery - 2018 Spring Cross Canada Lecture
by Thomas O'Rourke, Tuesday, May 22
The Boston Central Artery and Tunnel (CA/T) was the largest and most complex U.S. construction project in the last 25 years for which new technologies were developed and applied at an unprecedented scale. One of these technologies involves mass stabilization of weak clay by systematic deep mixing with cementitious products. On the CA/T, over 500,000 m3 of marine clay and organics were stabilized with the deep mixing method (DMM). The method was used under difficult conditions that included reinforcement of basal clay at an ongoing, unstable excavation and widespread application on a crowded site with especially deep, low-strength clays and many surrounding facilities.
Professor O’Rourke will provide an overview of the CA/T, including its cost and contributions to the urban regeneration of Boston. His presentation includes a case history covering ten years’ experience with ground stabilization on the CA/T. Topics addressed include water pressure distribution behind DMM walls, statistical characterization of soil-cement properties, quality control/quality assurance procedures, comparison of measured and numerically simulated deformation in clay stabilized with various configurations of soil-cement elements, and shear modulus degradation characteristics of in situ soil-cement. Recommendations are made for soil-cement properties, installation procedures, analytical modeling, design, and inspection.
by Lukas Arenson, Wednesday, May 2
Many mineral resources are in polar regions or at high elevations attracting mining companies from around the world. In Northern BC, or the South American Andes, such deposits are typically in remote mountainous locations and often at high elevations characterized by its challenging glacial and periglacial environments. Climate change is currently changing these mountainous regions rapidly, creating new landscapes and forming major changes to geo-hazards that affect the design of
infrastructure. In the dry Andes, periglacial landforms such as rock glaciers, protalus ramparts, gelifluction slopes, pattern ground and ice wedges dominate over glaciers and glaciarets. And despite the dry conditions, excess ground ice is frequently found resulting in challenges for infrastructure design.
The presentation focuses on engineering as well as environmental challenges that exist on developing and operating large mining projects in such mountainous environments. Results from complex site investigations recently carried out using advanced geophysical analysis techniques, as well as experience from the first sonic drill carried out in a South American in a rock glacier are
presented. Finally, challenges in communicating complex processes as well as how public perception affects large controversial projects are discussed.
Protecting Society from landslide hazard and risk – The UBC Geological Engineering 2018 Distinguished Lecture
by Suzanne Lacasse, Thursday, March 15, 2018
Risk is all around us: landslides, earthquakes, floods, storms and tsunamis are some of the daily natural hazards increasing risk to society. Quantitative risk assessment and risk management is needed because the future is not simply a projection of the present. This lecture will present the basic concepts of reliability‐based design and the principles for managing risk and achieving robust geotechnical designs. Case studies involving slope failures and landslide risk management will be used to provide illustrative examples. It will be demonstrated that our role is not only to act as experts providing judgment on factors of safety, but has evolved to providing input in the evaluation of hazard, vulnerability and risk associated with landslides. The conclusion is that our profession should be increasingly perceived as reducing risk and protecting communities.
The presentation slides are available here.
by Jamie Sharp, Wednesday, February 21, 2018
ConeTec completed a large and comprehensive nearshore geotechnical site investigation in the summer and fall of 2016 on behalf of the Port of Vancouver. This case history covers the preparation, execution, and initial data analysis aspects of the site investigation. The proposed Roberts Bank Terminal 2 Project will be a new three-berth container terminal at Roberts Bank in Delta, BC. The site will be located on reclaimed land immediately NW of the existing terminal, with water depths ranging from 4 m to 25 m. The field investigation included deep CPTu and SCPTu testing, downhole seismic testing, electric Vane Shear Tests, and sonic/mud-rotary boreholes with disturbed and undisturbed sampling. Concurrent with the field work, a comprehensive laboratory program was conducted by others. This presentation will cover innovations made and challenges faced while performing a nearshore site investigation for a major port terminal in a high-risk seismic environment.
by Kate Patterson, Wednesday, January 24, 2018
KCB completed a study examining and comparing dewatering technologies (e.g., thickened, paste and filtered tailings) to conventional slurry for the management of tailings (e.g., thickened, paste and filtered tailings) currently used in Canada. The strengths, limitations, and physical and environmental risks of these alternative technologies were compared to those of conventional slurry. Strengths, limitations and physical and chemical risks were considered across the entire life cycle of tailings facilities, from design and construction through to long-term post-closure.
The study applied the following approach:
- Conduct a survey to identify the current state-of-practice, and projects that use alternative technologies in Canada.
- Evaluate the alternatives, comparing tailings management technologies and costs using the information obtained in 1., along with case study information provided by select Canadian and international mine sites.
- Review advantages and disadvantages of the technologies, assess applicability to Canadian mines, and identify knowledge gaps.
The main conclusion from the study is that there is NO one-size-fits-all technology or management strategy and no technology should replace best practices in design, operations and closure of a tailings facility. This presentation will give high-level review of the study and present a snapshot of the current state-of-practice in the Canadian mining industry and key conclusions.
The presentation slides are available here.
vgs-tac new year's Talk - Landslide Risk Reduction in guatemala for homeowners in under-privileged areas
by Lauren Hutchinson, Tuesday, January 9, 2018
This meeting is being held in the Uber Room of the Steamworks Pub next to Waterfront Station (375 Water Street). Doors at 1730, talk begins at 1815.
BGC teamed up with two grad students to go to Guatemala and teach the local communities about rainfall induced landslides. Simple classification techniques (adding up some points to get a risk level) and mitigation options were taught to local NGOs and communities to assess the area. A short article about the work can be found here.
Probability Approach for Ground and Structure Response to GSC 2015 Seismic Hazard Including Crustal and Subduction Earthquake Sources
by Guoxi Wu, Tuesday, November 14, 2017
This presentation will provide an overview on how to make use of crustal, in-slab, and interface subduction hazard values from the 2015 GSC Model for the 13148 grid points (10 km by 10 km) in southwestern Canada (southern BC and western Alberta). USH spectra for crustal/in-slab earthquakes and USH spectra for Cascadia subduction interface earthquake can be derived at a couple of probability levels. Structure performance assessment can then be determined separately for the two main earthquake sources at a couple of probability levels. The overall probability at a given performance level (displacement, liquefaction or others) can then be determined by adding the probabilities from each of the two individual performance hazard curves. The overall performance (displacement, liquefaction or others) at a target probability level (e.g., 2%/50 years) is then determined from the overall combined performance hazard curve. Examples for determining seismic slope displacements from empirical equations (Bray and Travasarou 2007, Macedo et al. 2017) and for assessing site response and liquefaction using nonlinear finite element time history analyses (VERSAT, Wutec 2016) will be shown to illustrate the proposed procedure.
The presentation slides are available here.
Advances in Dam Design - 2017 Fall Cross Canada Lecture
by Jean-Marie Konrad, Wednesday, October 25, 2017
Embankment dam performance and life span are closely related to the hydric, thermal and mechanical behaviour of materials used during its construction. The apparent simplicity of embankment dams hides complex and often poorly known behaviours resulting from thermo-hydro-mechanical coupling phenomena. Understanding the different behaviours as well as their interrelationships is of paramount importance to optimize the life cycle of these structures.
Hydro-Québec Production obtained the necessary approvals to build a 1,550-MW hydroelectric complex on the Rivière Romaine, north of the municipality of Havre-Saint-Pierre on the north shore of the St. Lawrence. The complex will consist of four hydropower generating stations with average annual output of 8.0 TWh.
Construction of the Romaine-2 development began in 2009. Romaine-2 was commissioned in 2014 and the Romaine-1 development was commissioned in 2015. Work on the Romaine-3 and Romaine-4 developments, which will be operational in 2017 and 2020, respectively is underway.
Since 2009, the NSERC/HQ industrial research chair in Life Cycle Optimization for Embankment Dams contributed to the advancement of various aspects in dam design. Major developments for seepage induced erosion are presented. The use of centrifuge testing for predicting deformation of Romaine 2 are discussed. Rockfill properties are viewed from a fractal perspective.
Evergreen LINE RAPID TRANSIT: dEEP FOUNDATION AND GROUND IMPROVEMENT SOLUTIONS - aND ANNUAL GENERAL MEETING
by Ali Azizian, September 20, 2017
The 11 km long alignment of the Evergreen Line Rapid Transit (ELRT) project through Burnaby, Coquitlam and Port Moody consists of elevated and at-grade guideway sections as well as cut-and-cover and bored tunnels. Because of the high seismicity of the region, liquefiable and soft soils posed the main challenges for the design of structures. A performance-based design approach with varying levels of performance requirements were specified for the project. Several deep foundation and ground improvement solutions were used to meet the design objectives, while satisfying cost, schedule and site constraints. Foundation types included drilled shafts and driven steel pipe piles. Ground improvement solutions included Cement Deep Soil Mixing (CDSM) and driven timber piles. The presentation will provide an overview of the subsurface ground conditions along the alignment, seismic analyses (e.g. FLAC modelling), selected foundation or ground improvement types for each section, and some of the challenges faced during construction.