Devising new methods to assess ground stability
Mar 2012
University of Arizona News Release
- A University of Arizona geotechnical engineer has been awarded a US$1.25 million Federal grant to fund a five-year research project that aims to devise new and more reliable methods of assessing ground stability.
- Pinnaduwa Kumar Kulatilake, Professor of Geological Engineering at the UA College of Engineering, is being funded by the US National Institute for Occpational Safety and Health as part of a bid to reduce tunnel collapses, rockfalls and other forms of ground failure.
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High deformations threaten collapse in Albania
- Part of the current problem, according to Professor Kumar Kulatilake, is that current methods of rock assessment simply are not up to the task of providing a detailed picture of what engineers are truly getting into when they start blasting and tunneling.
- He has been appointed as sole principal investigator for a five-year project to develop new methods of assessing ground stability. The National Institute for Occupational Safety and Health, which is part of the Centers for Disease Control and Prevention, is funding the research.
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Research will focus on the strength and deformability of rock, which in turn depends on:
• What type of rock is present and how it behaves under certain conditions
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• Presence of joints, fractures and faults
• Stresses on the rock, such as pressure from overlying rock, or tectonic forces
• Groundwater conditions
• Stresses and forces present in the rock that will be released by excavation - Professor Kulatilake said: "The relationships among these factors are complex and it is difficult to determine rock strength and deformability, and thus ground stability, using the analysis techniques and limited field and laboratory investigations that are currently available."
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The unexpected defeats TBM work in Ethiopia
- During the project Professor Kulatilake will extend rock strength criteria he has developed to make them applicable in three dimensions. He will be working with two mines in the US and two mines in China to apply his new methodologies to underground and surface excavations to check how well they work in the real world.
- Kulatilake points out that it is not only miners who will benefit from being able to evaluate rock masses for potentially hazardous working conditions. "This is not only for mining," he said. "This work also relates to civil rock engineering projects such as tunnels, caverns, foundations, dams and slopes."
- To develop new methods of ground stability analysis, Kulatilake will combine field investigations and extensive laboratory testing, such as CT scans and three-dimensional load testing, with three-dimensional numerical modeling, including new theoretical concepts and advanced statistical and probabilistic procedures to quantify variability and uncertainty.
- His theoretical models will be made increasingly accurate over time as their predictions are validated using lab test results and field data. In essence, Kulatilake aims to bring more certainty to what is essentially educated guesswork when it comes to assessing ground stability.
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Professor Pinnaduwa Kulatilake
- "We have been using very simple methodologies in practice to address very complicated problems," he said.
- Another aspect of the problem is that assessing ground stability and preventing ground failure are extremely difficult. Because the number of experts in this area is decreasing, along with funding to train their replacements, a dwindling few remain to conduct these challenging assessments.
- In terms of creating a new generation of experts in this area, Kulatilake expects the research to lead to the completion of seven doctoral dissertations.
- "We need to have some young blood," he said. "It is time to create a new generation of professionals who are experts in ground control."
- The research findings will be incorporated in graduate courses that Kulatilake teaches in the department of mining and geological engineering and the department of civil engineering and engineering mechanics. And his teaching will extend beyond the University of Arizona: during the last 20 years, he has taught 52 short courses all over the world.
- Overall, Kulatilake expects his research results to provide a wealth of information related to excavations made for mineral extraction, tunnels for hydropower and transport, dams, foundations, natural and man-made slopes, underground caverns for oil and gas storage and human use, and hazardous waste isolation caverns.
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Symptoms of the collapse syndrome - TunnelTalk, July 2010
Adding the insurance payout consequence - TunnelTalk, August 2010
Five feared dead in Japanese tunnel collapse - TunnelTalk, February 2012
Koln – speculation and anger in collapse aftermath - TunnelTalk, March 2009
Space monitor for Hong Kong settlement - TunnelTalk, September 2011
Keeping Seattle safe on Alaskan Way TBM drive - TunnelTalk, February 2012
Success after mammoth struggles in Ethiopia - TunnelTalk, November 2009
Tunnel collapse in Albania closes highway - TunnelTalk, November 2009
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