Category Archives: Musings

This is the right way to dig a hole

The best children’s story is Mike Mulligan and his Steam Shovel. About this there can be no debate. It was my favorite story growing up, and it remains pertinent to my work today. You dads and moms can get a copy here: Mike Mulligan and Mary Anne

You’re welcome.

This is Mary Anne’s grandchild

It’s about a hardworking owner-operator named Mike, his stalwart coal-fired excavator Mary Anne, and how together they navigate the difficult transition from steam to hydraulic power in the North American construction industry. There’s a heartwarming ending. I won’t spoil it for you.

Pertinent today is the way that Mike and Mary Anne dig a hole: neat and square. At each stage the hole is manifestly neat and square. When they finish, you guessed it, the hole is neat and square. The book doesn’t emphasize excavation techniques; it’s not a trenching manual. Neat and square is just how Mike, an operator so skilled they wrote a book about him, digs a hole. If you’re not digging like Mike and Mary Anne, you’re probably digging wrong. Read by my parents with great enthusiasm, this story taught 4-year old me the two most important characteristics of an excavation:

  1. Neat
  2. Square.

I have time to write these thoughts on a Friday afternoon as the crew works diligently to wrap up a shoring submittal for a hole that is not square. Not by a long shot. It’s not pear-shaped or anything; but it zig-zags all over Honolulu through some comically soft ground. There are odd-angled corners. Several of them.

The reason that we’re struggling to wrap up the design is because I failed to insist that we dig like Mike. The Contractor, a highly experienced excavator, prefers long stretches of braced sheetpiles with open corners that allow in-trench pipe fusing. The the shoring has angles that are measured in 32nds of a circle. It is not at all square, and our bracing design are far from neat. The level of effort has more than doubled.

To avoid suffering similar difficulties, I encourage you all to stay true to the example of Mike and Mary Anne, a lesson so important that every right-thinking parent reads it over and over again to their budding young engineer-children. Dig your excavations neat and square. Your shoring designs will go smoothly, and your Friday afternoons will be greatly improved.

The Atlas Geotechnical crew is privileged to work all over the world, collaborating with squared-away engineers of varied backgrounds and sharing stories that range from tall tales to practical advice.

I’ve learned that every community includes at least a little folklore in how they design and build. Always there is some inexplicable local practice, unique to the area and unknown elsewhere, that designers, regulators, and builders all assert is necessary to project success.

A fairy tale is created when the lesson learned from a real experience, over time, becomes disassociated with its context and starts being applied to all projects. What started as sound practice turns into a guiding fable that, more often than not, just adds cost and difficulty without any benefit.

As an example: “House your family in the sturdiest structure you can afford” becomes, over time, “don’t build a house out of straw because a wolf will come and huff and puff and blow it down.” Practical advice. Brick houses are better against wolf-blowing and also generally. But if all you have is straw, and you’re a professional engineer, maybe your best course of action is to engineer a wolf-proof straw bunker.

Vibratory Pile Hammers: On Oahu in the early 1980’s a contractor was extracting timber piles from the sand backfill of a closed wharf, some of which were near the sheetpile quaywall. A few interlocks had separated below the waterline. Of course vibrating the sand flows it out the defective interlocks. Subsidence broke the wharf; it was a legitimate problem. Instead of learning to inspect interlocks before extracting waterfront piles, the Owner invented a myth that vibratory hammers are dangerous and shall not be used. Henceforth all piles, including sheetpiles, are driven with impact hammers. Far far away from the water, on different islands, specifications prohibit vibratory hammers. This Owner is influential; engineers accept that vibratory hammers are dangerous and ban them from all of their projects, not just their wharf projects. It would be a charming superstition if it weren’t so costly. Vibratory hammers have been proscribed for nearly 30 years. The engineer who made the rule nears retirement. It may take another 30 years for the fable to fade into distant memory and for Engineering once again to prevail in Honolulu.

Scarify and Recompact: In San Diego and parts of southern California, all earthwork begins (after stripping) by removing 6″ of soil, moisture conditioning, and rolling it back down as fill. Maybe at a few sites this upper soil might have been compressible, in which case for heaven’s sake perform remedial grading and make it suitable. But blindly converting 6″ of competent semi-formational flat ground into fill just increases your fill thickness. It is equally effective as stepping over the sidewalk cracks while walking home from school. Upon arriving you find that your mother’s back is, in fact, not broken. Maybe your superstition works; maybe you just walked home funny.

Detensioning Tiebacks: At this year’s Spring Seminar in Seattle an engineer asked a panel of experts “why does the City require detensioning tiebacks?” Two panelists offered straightforward answers: (1) “that started before I took over administering the rules,” and (2) “yeah, we’ve been trying to get that requirement dropped for years now, despite running full-scale demonstrations.” One senior community member shared a story from the ’80’s about a bar tieback that got broken and jumped part-way out of its hole. A close call, sure, but how does that experience relate to strand tiebacks with heads confined by a cast basement wall? Folklore. An irrelevant cautionary tale, pure and simple. That community has recognized it and, over time, will dispel the local myth that tieback strands are unreasonably dangerous.

So here’s the question: What folklore have you incorporated into your practice? I promise you there’s some nugget of superstition in your reports and designs that your peers in other regions would struggle to understand. Do you test micropiles using an ASTM setup instead of PTI? Do you insist that only your techs are capable of performing quality assurance testing? Require 6″ of compacted crushed rock beneath footings even in dry weather?

I don’t advocate that we expunge all local traditions from our work. Consider, though, examining your practices, understanding the origins of your folklore, and retaining just the beneficial parts. The practice of engineering evolves constantly through the work of our whole community. The generational shift currently in process is our opportunity to improve our practices and better serve our communities.

We’ve got a particularly interesting problem on our desks here at Atlas Geotechnical. There’s a lot at risk, various stakeholders are frustrated with and suspicious of each other, and there’s not enough time. While working this problem through to a pretty tidy conclusion this afternoon, it occurred to me to share the process that we use to achieve a safe, efficient design.

It goes without saying that rigorous project framing is critical to any problem. Define the boundary limits and success factors. Write, refine, and document the basis of design. There’s no point in working really hard late into the night when you haven’t defined the problem you’re trying to solve.

Even when the project is framed and bounded correctly, the juiciest problems always offer sticking points; places where the natural tension between resources, budget, and performance simply don’t allow a path forward. When I get stuck at one of those obstacles, these are the techniques (in order) that I use to crack it:

  • Collect More Data: Usually when moving quickly through a conceptual design you adopt conservative and simplifying assumptions about important parameters. The best way to solve a problem is to collect real data and refine the assumed parameters. This is the most self-contained and linear problem solving technique.
  • Challenge Your Assumptions: Sometimes you’re limiting yourself. A classic is that soils are normally consolidated, when really there’s a desiccated crust and settlement will be less. The always-dependable Mohr-Coulomb constitutive model is another bountiful source of limiting assumptions embedded in our most useful analytical tools. Engineers in my office call this “doing it the hard way” but if it solves the problem, and nothing else would, how hard was it, really?
  • Push Back on External Constraints: This one is particularly effective here at Atlas, but you need to understand the discipline that you’re challenging along with the hopes and dreams (and fears) of the team member who imposed the limit. Someone tells you that you can’t drill through a pilecap? Can’t tolerate more than an inch of differential settlement? Can’t pump more than 150 gpm? Discover the simplifying assumptions embedded in that limit; perform Steps 1 and 2 on someone else’s work, and find a way to preserve project performance without complying with a simplistic limit.
  • Call a Friend: I can’t tell you the number of times that this one has saved my bacon. If I weren’t so proud it would be higher on my list. Clever engineers have been solving problems for millennia; one of my friends has, almost certainly, previously solved the problem that has puzzled me for an afternoon. This one can be humbling; try to be gracious. The corollary to this technique is “try to have clever friends.” I’m good friends with several old guys who’ve been everywhere, done everything, and shoots do they ever help me crack troublesome problems
  • Hold a Meeting: Just kidding. Meetings never solve problems.
  • Get Away from the Problem: Irv Olsen used to go see a movie; one of my best friends, an astonishingly effective engineer, hikes like a maniac; I thought up this post while swimming laps. You serve your clients best when you’re thinking creatively and clearly. Don’t stay at your desk putting on a show of hard work when really you should stretch your legs, clear your mind, and actually perform engineering. Sure, you’ll need to start again with Step 1 once you’ve blown the cobwebs out, but you already got down to this last step once without solving the problem, so what other choice do you have?

I’m considering distributing laminated cards to the younger engineers here at Atlas outlining these four steps. That or hardhat stickers.

While not a panacea, I’ve found that there are very few intractable problems when clever engineers, given a clear mandate through good project framing, apply themselves vigorously and enthusiastically.

The last work week of the year is traditionally given over to strategic thinking. Essentially the workplace version of New Year’s Resolutions, it seems unavoidable that we spend this last week of the year contemplating our choices and planning improvements. Atlas Geotechnical is strongly committed to strategic thinking. Fully acknowledging that this is the most meta of all possible topics, here is our strategy for developing our 2019 strategy.

Three coincidental events prompted this thinking: reflecting on 2018 goals, a collaborator’s success, and feedback from a new friend.

  1.  Reflecting on 2018 Goals: One of our promising young engineers had a fantastic year of professional and personal growth. She performed new tasks that many engineers finish their careers without ever experiencing. She learned new tools. She’s a better writer. 2018 was undeniably a good year. Yet she did not accomplish even one of the “goals and objectives” that she and I together set at this time last year. The fault, if any is due, goes to me; I did not create opportunities for achievement. These goals checked all the SMART boxes, they were good goals. But they were necessarily established before the year had shown us what better experiences were to be had. We were right to take the better opportunities, but goals abandoned are not goals at all. For 2019, Atlas needs to articulate an over-arching framework that guides both goal-setting and goal-revision. We need a system for the adaptiveness that we improvised in 2018.

(I don’t want to bash traditional SMART goals.  They deserve a place in your planning.  Read more here: https://fitsmallbusiness.com/smart-goals-examples/)

  • A Collaborator’s Success: A longtime friend and co-worker shared positive feelings arising from demonstrating great decisiveness in making an important change. Normally contemplative and cautious, he made a good decision quickly and then kept believing in it. Decisiveness like that can’t exist without optimism, the idea that committing to a path will work out well (or can be made to work out well enough, if necessary).  Decisiveness, optimism, and confidence aren’t goals. They’re behaviors that sure do help achieve goals once you set them. I believe that cultivating decisiveness and optimism couldn’t be a precursor step that could unify our 2019 Strategic Plan.
  • Expert Insight:  A new friend described my writing here as “vigorous.”  He earns his living in academia. He’s a professional thinker, a person who illuminates ideas that remain obscure under less-acute inspection.  Vigorous. What an excellent, concise adjective. His comment resonates especially because he is unfamiliar with the details of our work here at Atlas, so he is describing the image that we project rather than the outcome of our work.  It so neatly encapsulates my love for our industry and the importance of our work. All engineers should all strive to be vigorous in our work. My practice, and Atlas more generally, will succeed in 2019 when I expand on an attribute that I already have and approach all our work with even greater vigor.

Eric Resseler, founder of Cosmic and the teamleader who created this website, helped me focus these three experiences into (to me) new line of thinking. The guiding framework for adaptive goal setting is a “theme.” Though not specifically intended for business strategy, consider reading this year-old backgrounder about Themes:

https://www.psychologytoday.com/us/blog/wander-woman/201701/set-your-theme-the-year-you-set-your-goals

Eric has a fresh approach to strategic marketing that I find useful.  Read here: https://designbycosmic.com/insights

Before setting 2019 goals, consider your strategic theme. A young engineer might focus on collecting divers new skills and experiences. My collaborator felt buoyed up by his decisiveness, and more like that might make for greater progress over the course of the year. For me, I want to focus on restoring true vigor to my practice after a couple of wearying years.

Atlas Geotechnical’s 2019 strategic theme is readiness.  This year our goals will focus on honing the knowledge, systems, and resources needed to effectively serve our clients and their projects. 

  1. Atlas will emphasize staff development in all of its forms and will take advantage of opportunities as they arise.
  2. I am optimistic that by September we will have re-established our capacity to support any project anywhere in the world. Confidence in our financial resources facilitates decisiveness in accepting new projects.
  3. Our maturing safety program will assure that we can show up ready-to-work at any site in the world. Investing in safety training during slack times allows focus on logistics and analyses at project kickoff.
  4. Personally, I’ll improve my effectiveness at work by finally taking on restorative breaks.  The first half of 2019 is my time the sharpen my tools, whether in the pool, in the ocean, or in the mountains. Time with family and friends is a part of cultivating greater vigor back at my desk.

I hope that sharing our approach offers something useful as you contemplate your own 2019 goals.  Consider the triumphs and disappointments of 2018, choose a theme to guide you in 2019, and commit to your theme before setting your new goals.

Happy new year. It’s going to be a great one for all of us.

I just started work on a piledriving project where the GT of Record provided final tip elevations, based on 16 indicator piles, for the Contractor’s use in casting the design lengths. With the diagram he included a disclaimer that the site is variable, and that many of the piles might be different lengths in order to satisfy the acceptance criteria. The GT, accompanying the final design information, recommends that the Contractor hire another geotechnical engineer to monitor each production pile and make appropriate length adjustments, and also a structural engineer to design splices.  Without intending, I’m sure, the Owner’s engineer has converted the piledriving part of our project from conventional design-bid-build to a contract that relies on the Observational Method.

The Observational Method is extraordinarily effective on challenging sites, but also can be costly to implement. We use it explicitly on dams and tunnels. Ralph Peck’s 1969 Rankine lecture is, in my opinion, the best summary of the method’s origins, the rigor with which it is to be applied, and it’s significant advantages on projects with terribly difficult geotechnical conditions. Like all Rankine lectures, the paper is worth a read.  You can get your own copy here:

https://www.britishgeotech.org/prizes/rankine-lecture

I link to the full catalogue; scroll down to 1969.  Consider browsing a bit while you’re on the site. And yes, the photo that accompanies this post is my preferred headshot of Karl Terzaghi, not the author. Read Prof. Peck’s paper to understand why.

In my practice I find it helpful to recognize when the design team’s RFI responses induct elements of the Observational method into our project. When they do, it’s time to  evaluate whether or not the character of project has changed fundamentally from the project described in the bid documents. A conventionally procured project offers certainty in exchange for hard bid pricing. Other tendering formats are appropriate for projects where final design will be developed as conditions emerge, as is the case with the Observational Method.

It’s necessary to understand the Method in order to recognize unintentional implementations. Here’s a clip from Prof. Peck’s lecture, for those of you with just passing curiosity.

REVIEW OF METHOD

In brief, the complete application of the method embodies the following ingredients.

  • Exploration sufficient to establish at least the general nature, pattern and properties of the deposits, but not necessarily in detail.
  • Assessment of the most probable conditions and the most unfavourable conceivable deviations from these conditions. In this assessment geology often plays a major role.
  • Establishment of the design based on a working hypothesis of behaviour anticipated under the most probable conditions.
  • Selection of quantities to be observed as construction proceeds and calculation of their anticipated values on the basis of the working hypothesis.
  • Calculation of values of the same quantities under the most unfavourable conditions compatible with the available data concerning the subsurface conditions.
  • Selection in advance of a course of action or modification of design for every foreseeable significant deviation of the observational findings from those predicted on the basis of the working hypothesis.
  • Measurement of quantities to be observed and evaluation of actual conditions.
  • Modification of design to suit actual conditions.

The degree to which all these steps can be followed depends on the nature and complexity of the work.

I am particularly fond of that last statement. “It depends.” In the 50 years since those words were penned by one of the giants in our field, consulting geotechnical engineers have yet to address the fact that, really, the right course of action depends on the nature an complexity of the construction. There is always a way forward, of course, eVen in the most difficult conditions. The level of effort, though, depends on the nature and complexity of the work.

 

One benefit of working with friends is the non-work time we spend together, like sharing meals.  Longtime collaborator and good friend Steve Dickenson joined us in San Francisco for a project meeting last week.  While the meeting achieved the intended outcome, the real highlight of the day was the excellent bahn mi sandwich shop that we found on Eddy Street.  L&G Vietnamese Sandwich is a no-nonsense, locally owned, quick service shop. Lunch for the three of us cost less than $20, which surprised me considering we were in the middle of San Francisco.

The bread had the exact right texture, the jalapeno slice on top added the right amount of bite, and the rest of the ingredients were super fresh. There’s no seating in the shop, but there’s plenty of great public space in the neighborhood.  Here’s their website in case any of you guys need to pre-order before your next meeting in the Civic Center neighborhood:  http://orderlandgvietnamesesandwich.com/

The Atlas Geotechnical blog doesn’t really focus on restaurant reviews, but the unique experiences we collect in the course of our work-related travel are a thoroughly satisfying part of our careers. From Seattle seafood to a great hole-in-the-wall yakitori place on Oahu, from proper Kansas City bar-b-que to amazing camp meals in Athabasca, we share a lot of great meals with good friends as a direct result of our unique engineering practice.  Sharing great bahn mi with a good friend in San Francisco is another great memory from a 30-year engineering practice that just keeps getting more and more interesting.

Dinkey Creek BridgeIt’s not often that anyone sees the best geotechnical designs.  Dams, maybe, but even with those the classics are all concrete arches. I guess none of us here at Atlas, or any or our geotechnical brethren, chose this career path for the glory.  Those people were all drawn to architecture. Except for a select few who found bridge engineering. That’s one engineering discipline where function and aesthetics blend seamlessly, and where an excellent design is obvious to all onlookers and not just the engineers among us.

And while Portland has recently finished a marvelous cable-stayed crossing of the Willamette (http://trimet.org/tilikum/), I reserve my greatest appreciation for projects that were built without access to the unlimited might of modern construction equipment. A timber bridge built by sincere but untrained CCC crews is somehow in a different category for me, and generates a special kind of appreciation.

Doug Export - 20We came across this classic beauty several years ago while bouldering as a family through Dinkey Creek.  The simplicity of the design was striking, and we paused for an impromptu discussion of load paths, Newton’s second law about actions and reactions, and how to use the method of sections for analyzing trusses.

The budding young scientist in orange standing beside me (and asking insightful questions) started college this past week.  His intrinsic appreciation of beauty in the functional world draws him to studying physics, a significant step up from his dad’s mundane plodding in the mud.  He has a burning interest in answering the most fundamental questions, not simple ones like “how can we cross this creek using hand tools and the forest around us.” I hope that he, and all of us, can find elegant, enduring solutions to the important questions that we consider.

We’ve recently found ourselves working on several projects afflicted by badly flawed numerical modeling.  And not just little errors with inconsequential effect.  These mistakes demonstrate a fundamental misunderstanding about how numerical models work and how to deploy them in Engineering. All of you surely have your own examples of numerical modeling gone awry; here are the two most recent from our practice:

  1. Search constraints in a slope stability model were deliberately set farther upslope than the slope geometry could possibly support, so the Engineer was unwittingly searching for failure surfaces other than the critical surface.  I told the Engineer that the computed safety factor was only valid if the lower (less-stable, light blue) part of the slope could reach up across that little narrow neck at the scarp and grab the upper part (yellow-ish), dragging it down the hill like the caboose on an impossible failure-train.  Yes, we’re interested in the stability of that area back from the crest, but no, forcing the model to violate the basic premise of Method-of-Slices stability analyses does not provide useful insight.Block_Yield Acceleration_Page_1 (2)
  2. Hydrotesting a new canola oil tank caused it to tilt 275 mm across the 36 m diameter. An Engineer was engaged to assess the structural integrity of the tank and, unfortunately, interpreted that assignment as license to run wild with a bunch of structural finite element software. One of the runs showed tank shell stresses 3.5 times higher than the steel strength, which would have caused catastrophic failure before the end of the hydrotest. When I observed that the tank is still standing and the computed result contradicts observed fact the Engineer doubled down on his computations, effectively stating that reality exists in the computer, not the tank.Tank 42

 

It seems to me that modeling failures like these are increasingly frequent as mesh generators and improved interfaces make the software more accessible. The improved speed and efficiency that facilitates competent modeling are just as helpful to the ignorant modelers, allowing them access to new tools that they do not understand and yielding answers that do not represent actual conditions.

I expect that, over time, a few designs based on flawed models will find their way into our built infrastructure. I hope that the resulting losses are only financial, and that before too long we find a way to re-emphasize the proper relationship of modeling in support of engineering, rather than modeling as a time-saving substitute for engineering.

This week between holidays is, without question, my favorite work week each year. This is the week where I clear the decks in preparation for an unencumbered start.  I sort out whatever fussy administrative problem was allowed to linger unresolved in favor of shopping and year-end accountancy. (This year it’s an off-site backup problem; last year was an office furniture need). My white board here at Atlas World Headquarters is full of good uses for this period of predictable calm, and I’ve already started knocking some of them off the list.

For those of you who make resolutions, this is the week that you compose and commit yourselves to making that long-overdue improvement in your practice. Those of us who prefer to skip the resolution stage and simply do the thing, this is the week to make a start and see if the new habit will stick.

We should all recognize how much more productive we are when free of distracting email and conference calls.  Creating such periods of uninterrupted productivity is going to be an important improvement to my practice in 2015, and I would recommend that it be part of yours too. (I use Freedom to turn off teh Interwebs. https://macfreedom.com/  There are many similar programs, and you should use this week to find the one that works best for you.)

Whatever you intend for your practice in 2015, whether you’re still building core competency, diversifying and growing, or starting to contemplate ramping down, I wish you the very best of luck for this preparatory week and great success in the coming year.

TJ Earthquake Damage

Typical Damage at Trader Joes

Friday night’s earthquake in La Habra was interesting for a couple of reasons.

It was small, by California standards, at only Magnitude 5.1.  In fact, I have my automatic notification program set to M6.0 or larger because there are so many small earthquakes like this and generally they don’t cause any damage. I found out about this one through Facebook. So I guess yes, there’s at least one good use for Facebook.

Secondly, the shaking was surprisingly strong for an earthquake of this size.  The rupture was shallow, only 1.7 km deep, and the lack of attenuation up to the surface resulted in  peak ground accelerations as high as 0.25g.  I pasted the USGS shake map below with a handy key to the Mercalli Intensity Scale system of classifying earthquakes.

No serious structural damage occurred, though La Habra Utilities is reporting broken water and gas pipes. The lack of damage and injury speaks more to LA’s excellent building codes and earthquake preparedness than it does to the modest earthquake size. In other parts of the world, places that lack the resources, knowledge, and political will of metropolitan Los Angeles, these types of earthquakes cause fatalities. Intensity VII shaking in California knocks over a stack of wine bottles in Trader Joes. The same level of shaking in rural Afghanistan dislodges roofing stones from their timber supports and buries whole populations in their huts.

Small, generally consequence-free events like these are an opportunity for all of us to reconsider our knee-jerk reactions to troublesome regulations and building codes, a chance for us to give genuine thanks to the smart engineers who led the transition from unreinforced masonry buildings like San Francisco had in 1906 to the well built structures that now protect us from preventable misfortune. Here’s my list of earthquake heroes:

Harry Seed – Pioneer geotechncial engineer and shining light of inspiration

John Lysmer – Smartest good-humored numerical modeler

Vitelmo Bertero – Structural engineer, deep thinker, curmudgeon

CB Crouse – Towering intellect, practical seismologist, mentor

Steve Dickenson – Good friend, collaborator, and insightful earthquake engineer

Yumei Wang – Classmate and dedicated earthquake safety advocate

Jason Brown – Cheerful building code enforcer

Because of their work and the work of countless others, your home and office, your kid’s schools, the bridges that you cross, the port that handles your cargo are all safe from damage in these types of events.

Here’s the link to the USGS event summary, for those of you with interest:

http://earthquake.usgs.gov/earthquakes/eventpage/ci15481673#summary

Be safe, everyone.

La Habra Shake Map