On May 2021, a slope failure called “Leo Failure” occurred at Bingham Canyon Mine, one of the world’s deepest open pit mine, for a total runout mass estimated at 21 MT. Extensive and comprehensive monitoring of the mine activities allowed to anticipate and record the event and prevent any labor or equipment damage.
The Nuclear Waste Management Organization (NWMO) worked with Itasca to assess the risks of a potentially large earthquake near a generic DGR that could cause enough deformation or movement on secondary fractures to damage waste canisters and/or provide potential pathways for radionuclide migration.
In Sweden, the Forsmark site, a sparsely fractured crystalline host rock, is selected to be the future location for building a deeply sited nuclear waste disposal. The use of highly detailed DFN (Discrete Fracture Network) based site models is required for both post-closure safety assessment and construction purposes. DFN-based models are considered the most accurate representation of the fractured system and of the geological context.
In early 2021, the eastern wall of the WCP experienced significant displacements after the active mining reached weak diabase sills at the toe of the open pit. Itasca used FLAC3D to back-analyze the open pit slope displacements measured by radar and inclinometers. The use of the IMASS (Itasca Model for Advanced Strain-Softening) constitutive model enables the representation of emergent damage and strength loss, rather than predefining it.
LKAB’s Kiirunavaara Mine is a large, underground, sub-level caving mine that has been seismically active since approximately 2008. With this seismic activity comes associated vibrations. These vibrations can be felt on surface in the town of Kiruna, which is currently located close to the mine on the hangingwall side. The mine is undergoing a national permitting process concerning a desired increased production rate. An important question for this process is: will the increased production rate result in changes to vibrations in the town due to seismicity?
In general, analysis performed on wind turbine foundations focus on the effects of the foundation’s rotational stiffness and deformation for a range of overturning moments. This project stage focused on the performance of the foundation and, given the local soil condition, its bearing capacity. To evaluate the behavior of the soil-structure interaction, a detailed numerical model of the concrete foundation and its steel reinforcement (i.e., rebar) was built and analyzed in FLAC3D.
Located in Catamarca Argentina, the Bajo de La Alumbrera open pit mine experienced a large-scale instability along its southwestern wall on May 31, 2017. Itasca performed additional numerical modeling analyses to back-analyze the 2017 instability to predict Factor of Safety (FS) contours and consider options to mine the remaining ore at the bottom of the pit.
Site modeling using DFN.lab (2021)
In Sweden, the Forsmark site, a sparsely fractured crystalline host rock, is selected to be the future location for building a deeply sited nuclear waste disposal. The definition of highly detailed, and DFN (Discrete Fracture Network) based, site models is required for both post-closure safety assessment and construction purposes. DFN-based models are considered as the most accurate representation of the fractured system and of the geological context.
Exploration between the two closed mines Rävlidmyran and Rävliden has
successfully led to more mineralizations being discovered. Itasca has analyzed possible mining methods, mining sequences, design parameters, location of infrastructure, reinforcement, and backfilling requirements. A
Research, Numerical Investigations and the Development of a Methodology for Longwall Mining at a Potash Deposit (2021)
Aim of this R&D project is the development of guidelines for the estimation of the water-conducting crack propagation above mined-out spaces above a potash deposit, using research and numerical modelling methods.
Wind farm construction requires large cranes to lift massive wind turbine structures over 300 feet tall and exceeding 160 tons. Installing these structures requires many crane “walks”, moving the heavy cranes around 50 miles along soil surfaces of varying strengths. Moving the cranes quickly is critical to installation economics, but this must be done safely by ensuring soil strength stability to avoid sinking or toppling the crane. Conventional best practices require cone penetrometer tests (CPTs) and performing numerical modeling to establish a safe path for moving the cranes requires on the order of four to six weeks. Itasca developed a rapid bearing capacity prediction tool using Python scripts, FLAC3D, and machine learning to provide near real-time feedback on the soil bearing capacity at a location, allowing enhanced crane walk planning.
For pile groups with a relatively large pile cap, the geotechnical failure is generally not the controlling failing mechanism of the system. It is almost always settlements, rotation, or performance that controls the design.
In this project, the effects of deformation and rotation with regards to the pile length were observed. Specifically, four piles of a pile bridge were driven through an intermediate sandy layer and may have encountered a local anomaly (Figure 1). A safe assumption was to consider the anomaly to be clay. Additionally, the benefit of any additional helping elements to balance the stiffness distribution of the pile under the pile cap were evaluated.
The objective of the project is to predict the scaling evolution of rock mass effective elastic properties for conditions relevant to the POSE (Posiva’s Olkiluoto Spalling Experiment) niche surroundings at ONKALO, the Finnish site for underground storage of nuclear waste.
SKB is interested in developing a 3D discrete model to predict spalling on the excavation boundaries of underground repositories for the long-term storage of spent nuclear fuel. This project provided a quantitative assessment of modeling spalling using PFC3D to study both lab- and tunnel-scale behavior.
Long-term storage of spent fuel is critical to the nuclear energy industry. The Swedish Nuclear Fuel and Waste Management Company (SKB) is developing an approach for the storage of spent nuclear fuel in an underground repository in competent crystalline rock. In order to better understand the spalling damage process, an in-situ test involving the drilling of two boreholes was performed in Äspö diorite at SKB’s underground hard rock laboratory in Äspö. Tests and monitoring were performed on the pillar that separated the boreholes. In order to further investigate the damage process, Itasca performed numerical modeling using PFC3D and FLAC3D.