DipAnalyst: A New Kinematic Analysis for Rock Slopes

Last week I had the pleasure of sitting down with Dr. Yonathan Admassu, creator of the new slope stability software: DipAnalyst.  Dr. Admassu earned his Ph.D. in Applied Geology at Kent State University last year and is currently teaching courses in geology, oceanography and geographic information science at Kent State University at Ashtabula in Ohio.

Dr. Admassu began his career in geology as a student in Ethiopia many years ago.  It was very interesting hearing why Yonathan had chosen geology.  For many of us, geology is something we grew up loving, even if we didn’t realize it at the time.  I’ve been fascinated by rocks and minerals since I was a child, collecting the pieces of limestone gravel in my parents’ driveway.  I also knew the names of all of my toy dinosaurs and when the toy companies that created them had inaccurately molded the plastic: T. rex doesn’t have three fingers!  Brontosaurus’ tail didn’t drag on the ground! (Yes, Brontosaurus was still a legitimate name back then).  While my exact focus in geology wouldn’t become apparent until college, I knew from an early age that my career would be founded in the earth sciences.

Geology was not Dr. Admassu’s childhood dream job.  In actuality he had aspired to become an engineer.  However, at this time in Ethiopia, there were very limited positions available in the engineering program at the only University in the country.  Admission was extremely competitive and,  when his grades turned out to be less than 100th of a point shy, he went with his second choice: geology.  When I questioned how he chose geology, Yonathan explained that he honestly didn’t know a lot about the field at the time, but that he did know certain aspects could be applied to industry.

Dr. Yonathan Admassu, author of DipAnalyst

Upon graduating with a Bachelors Degree, Yonathan began working in exploration looking for gold and other economically important metals.  Realizing just how much his contributions as a geologist could change people’s lives, and even entire economies, his interest in geology skyrocketed.  This, I’m sure, is also when he realized that he made the right decision when choosing geology as a career path!

By the mid-1990’s, however, the price of gold was dropping…and so were projects in exploration.  Yonathan was now looking for something that would allow him to continue his passion of applied geology, but that would remain unaffected by the ups and downs of markets.  This is when he decided to travel to the United States to complete his Master’s Degree, and later, Ph.D. studying engineering geology.  Here, Dr. Admassu would focus on rock slope stability.

Plane failure within a slope consisting mostly of sandstone

While working on his Ph.D. dissertation, Yonathan felt the current slope stability programs were not quite addressing his needs.  Such programs as RockPack, Slide, and Dips conduct a kinematic analysis which, in terms of rock slope stability, determines if one or more of several types of slope failures (see the figure below) are likely to occur.  In order to do this, the programs analyze data collected from a rock  slope – including slope angle, joint spacing, angle of internal friction, and several other variables – and calculate if failure will occur.  Many of these calculations are based on representative values of the dominant discontinuity orientations as determined from plotting them onto a stereonet.  This type of analysis relies on groupings, or sets, of discontinuities so that a representative value can be applied (i.e. – 1 value for 1 cluster of data points).  The results of a kinematic analysis are typically presented in a qualitative manner: “Yes, a failure of this type will occur” or “No, this type of failure will not occur”.

Much of Yonathan’s data appeared to be more spread out, with no clear representative value to choose.  While for cases like these there are methods out there which can be used to select a value, Yonathan wanted something more quantitative, that gave a better idea of how likely failure is to occur based on statistical analyses.  This is where he began to develop a new kind of kinematic analysis.

Slope failures associated with unfavorable orientation of discontinuities (modified after Hoek and Bray, 1981)

In Yonathan’s analysis, all discontinuities would be entered into the equation, even if they couldn’t be grouped into a set.  By conducting the kinematic analysis this way, he was able to come up with what he calls “failure indices”, a quantitative, probabilistic result for any given failure mode.  For example, instead of “Yes, plane failures may occur”, the results would show a failure index of 0.5 for a plane failure, indicating that 50% of the discontinuities are capable of this type of failure.

As I had mentioned, Dr. Admassu began developing this new kind of kinematic analysis while working on his dissertation.  He could have stopped there, but instead decided to teach himself computer programming and develop software to conduct these analyses for anyone that wanted to use it.  This is how DipAnalyst was born.  The software itself is centered around this analysis.  All the same information that is plugged into any other slope stability software is the same that is used here, so it doesn’t take any more time or effort to input your data, and yet it gives you a better idea of the likelihood of failure.  In addition to calculating failure indices, users are able to conduct the traditional stereonet method of analysis as well as sensitivity analyses to see how the likelihood of failure changes as you change parameters such as the slope angle, azimuth, and friction angle…which is important to know for slope design.

My one major concern was that a low failure index value, say 0.05, seems to imply a “safe” slope, but really means that 5% of discontinuities are likely to fail by whichever mode you are analyzing.  Yonathan addressed this in two ways.  He pointed out that the sensitivity analysis can be used to determine what slope parameters have an affect on the failure indices, allowing you reduce the failure index to a more acceptable value.   When making adjustment like this, as with any type of analysis, you cannot underestimate the importance of applying judgment (out of experience!) to your results.  He also agreed that this could sound misleading, and that more research must be done to determine what could be considered a “safe” index value, or if nothing above 0.00 is acceptable.  Keep in mind that DipAnalyst was created as a method for designing slopes…you can always adjust your slope angle and azimuth until the failure index is zero (no chance of failure)…your limiting factor in most cases will not be the failure index, but time and budget.  After all, it’s expensive to engineer a slope!

Dr. Admassu sees his software being applied mostly in highway design (road cuts), the mining industry, quarries, and any other industry involving rock slope mechanics.  So far, people from all over the world in these industries as well as universities have used this software and are giving feedback (which he greatly appreciates, by the way).  Yonathan has also sent his software to several professionals, some of whom have developed their own programs, who have given great reviews.

Dr. Admassu doesn’t see DipAnalyst as competing with some of the rock slope stability software already widely available, specifically because it’s a different kind of kinematic analysis and because, at this time, factor of safety calculations are not a part of the program.  However, he does feel it is a valuable tool that could prove indispensable to any slope stability project.  Additionally, features such as pole contouring and factor of safety analysis may be in DipAnalyst’s future.

As a follow-up question, I asked Yonathan to give a quick statement as to why people (like you) should use his software:

[DipAnalyst] is very simple to use and easy to understand.  It’s a different approach from what we already have.  I believe it is an additional contribution to our field.

  • Visit DipAnalyst.com to learn more about the program, its author, and how kinematic analysis works (using both the standard Markland Test method as well as Dr. Admassu’s method).
  • If you do use DipAnalyst, or have questions about the software, Dr. Admassu would love to hear from you!  Contact him at: dipanalyst at gmail.com

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