Wednesday
Aug292018

Project Spotlight: 8/29/18 Geopier® ground improvement transforms soft site in Tulsa, OK

A Manufacturing Facility in Tulsa, Oklahoma with a Unique History

We talked to Vaughn Rupnow, P.E. about the latest Geopier® ground improvement project completed in greater Tulsa, Oklahoma.

Ground Improvement Engineering (GIE) and Geopier Foundation Company designed the Geopier support for a 1.8 million square foot tissue paper manufacturing facility in greater Tulsa, Oklahoma.

This site has an interesting history. Back in the late 1970s, a local energy provider started constructing a nuclear power plant there. However, public outcry derailed the construction and the plant concept had to be abandoned. But not until some infrastructure was in place including the reactor pit, rail sidings and underground utility lines. The energy provider marketed the property for years until a tissue paper manufacturer came to the table.

A geotechnical engineer was brought on board to provide building support recommendations.  Their exploration found fill up to 20 feet deep and compressible native soils as deep as 40 feet. These conditions were not feasible for a conventional, shallow footing foundation system.  The engineer gave a variety of foundation support alternatives such as over-excavation, end-bearing drilled shafts, and Rammed Aggregate Pier®.  

The design team weighed the costs and schedule of each alternative; they concluded that Geopier would meet the settlement criteria at an economical price; furthermore the piers could be installed rapidly. 

The project team did resort to pile foundations in a limited, very settlement-sensitive building portion but most footings would bear on improved soil.

 Multiple Crews install Geopier GP3

The project broke ground during the first week of February and our Geopier installer, Peterson Contractors, Inc. (PCI) began building Rammed Aggregate Pier elements in late March. GIE observed the installation of the modulus test elements and reviewed the PCI quality control records. 

PCI is using both the Geopier GP3® and X1® technologies, with X1 for the deeper fill and soft native soil areas. PCI completed the field work by the end of June; the overall project completion is scheduled for mid-2020.

 

Wednesday
Jun272018

Leading Thoughts: 6/27/18 Utility Lines and Geopier® Ground Improvement

“I have some new and existing utilities on my site.  How does that work with the Geopier® ground improvement system?” 

Today’s new structures have old and new utilities that traverse the building footprint and we as the design team and contractors have to problem solve and plan for these utilities so that the project runs smoothly.  The Geopier® system installation increases the lateral soil pressure which contributes to the frictional resistance required for its capacity.  When you dig too close  to the Geopier element, this can reduce some of the lateral resistance and the Geopier can lose both capacity and integrity.  So, let’s go through the different utility locations and elevations to provide an early solution before it becomes a problem later in the project.

Do you have an existing utility?

If you plan to move the existing utility, please just follow any recommendations provided by the Geotechnical Engineer of Record for correct backfill once it is removed.  Remember, if granular backfill is planned to fill  the utility excavation, you may want to consider including some fines in the fill materials so that it does not cave during a “drill and fill” Geopier installation.  If you plan to abandon the utility in place, you will need to ensure that the location does not conflict with any of the required pier locations (i.e. below a column, corner of the building, etc.).

Does your new utility run above the footing?

If your utilities, like much of the interior plumbing and electrical lines, run above the bottom of footing elevation you have no issues for foundation support with the Geopier systems.  If these utilities have to exit the structure, typically these utilities will be placed in the foundation wall through a sleeve.  Occasionally however the utility lines are placed below the perimeter footing elevation.

Does your new utility run below the footing?

If your utility runs below the footing, you will need to check the elevations and utility locations.  

More than 2 feet below the bottom of footing. 

We typically ask that utilities that extend more than 2 feet below the bottom of footing elevation be placed prior to the Geopier installation and clearly marked in the field for our Geopier installers.

Within 2 feet of the bottom of footing elevation and runs next to (parallel) the footing.

A utility placed after the Geopier installation must be outside of the “no dig zone of influence” as seen in this sketch.  If the utility is outside of this zone, then there isn’t an issue.  If the utility will be within this zone, you will need to move it outside of the no dig zone or install it prior the Geopier installation.

 

Within 2 feet of the bottom of footing elevation and crosses (perpendicular to) the footing

In this case, we just ask that you can provide the Geopier designer the approximate location so that we can bridge the utility with elements on both sides of the utility in our shop drawings.   This bridging can be done in the field as well if the utility is placed prior to the Geopier installation.  Once the utility is placed, please follow recommendations of the Geotechnical Engineer of Record for backfill of the trench. 

I have floor slab support and utilities.  Does this change recommendations?

If you are providing floor slab support with the Geopier system, it is important to coordinate the utility locations and attempt to avoid the piers.  If the pipe alignments have to be maintained as designed, it may be necessary to offset the Geopier elements, install additional elements to “straddle” the utility pipes, or expect damage to the piers that will be fixed with highly compacted granular backfill.

Once the utility is placed, it is imperative that the trench backfill be properly compacted per recommendations of the Geotechnical Engineer of Record.  After all, any backfill placed after our pier construction also support the floor slab!

Final thoughts…

Utility questions are common and we have just “scratched the surface” with this article. Sometimes even carefully coordinated utility plans can result in unavoidable conflicts with the Geopier no-dig-zone.  Design accommodations can be made for complex utility arrangements, so please call your Geopier designer when a more detailed evaluation is needed.   We’ve dealt with these issues for many years so make use of that experience!

 

Monday
May142018

Leading Thoughts: 5/14/18 Could Geotechnical Engineers be Replaced by AI?

Charles Allgood, P.E., LEEP AP considers AI and the future of geotechnical engineering.

It seems that everywhere you turn there are conversations, articles and pundits discussing Artificial Intelligence (AI).  Some point to a bright future for humanity while others are pessimistic and talk about AI replacing people and doing their jobs better.

Young adults face an interesting dilemma that those of us currently working did not have to consider: choosing a career that will not soon be automated. The McKinsey Global Institute estimates “that half of today’s work activities could be automated by 2055.” This made me wonder about AI and automation in the geotechnical engineering profession. Who might be replaced and what would the workplace look like years from now?

While we explore this topic I am also going to ask you the reader some questions.  It would be interesting to get your perspectives.  There is a link at the end of the article to send your ideas and I will write a follow up article highlighting them!

There are geotechnical data gathering/testing methods that might be automated; we’ll explore a few possibilities.  We also know that geotechnical engineering requires judgment; this is based on experience, knowledge of the local geology and contracting methods, historical knowledge, and other variables.  But could the “human” element be captured by a self-learning AI under the tutelage of those experienced engineers? What do you think?

Here are three tasks in geotechnical exploration that could be automated relatively soon; afterwards we will talk about areas that may be difficult to automate.

Three tasks that may be automated:

 

Data Collection

Geotechnical engineers collect information on soil, groundwater and rock conditions.  Perhaps going forward the exploration begins with an AI searching for the available digitally-stored open-source data on historical property usage, the boring and well logs stored on agency or firm computers, aerial and old photographs/survey data, etc.  This information would help characterize the site before the exploration begins.  There is a lot of information out there and AI should be able to find it much better than we could. How many times have you drilled borings on a site only to find out that others have drilled there before you?!

Afterwards the field work could be supervised remotely by AI with robotic drill/sounding rigs performing the work. Do you think this is possible soon? If un-manned rovers on Mars can determine chemical and composition characteristics of soil and rock how far away are we from doing much more here? Drilling is a dangerous business so automation would be attractive. 

Soil Classification/Lab Testing

The field sample containers could be brought into an automated lab by aerial drone, with bar codes to identify the individual samples.  It should be possible to develop robots with the ability to test soils for texture/grain size, moisture content and even plasticity.  An AI could then assign additional lab testing based on project needs.

The structure for this is already in place with cross-over testing and quality inspection technologies from other industries, automated soil testing machines, advanced robotics and electronic boring logs.

Are there other tasks you think will be easy to automate?

Geotechnical Report Writing

Using the collected data AI could complete the analyses and engineering report.  This could be similar to the AI tool Reuters is building.  The software is already in place to analyze bearing capacity, settlement, stability, overlapping foundation stresses, earth pressures and other more complex 3-D modeling.  The AI would already “know” the entire library of geotechnical knowledge and have that to draw upon.

The AI could select foundation, floor slab, pavement, slope, retaining wall and other structure support recommendations.  These would be based on the initial client needs for settlement control, floor deflection, LEED® certification, or any number of requirements.

During the AI learning process human engineers would evaluate whether the recommendations are practical and advise on how to proceed.  Every time thereafter the AI should learn and get better.  Hopefully they won’t get too good at this!

Think about how long it takes to train a young engineer out of school to become a productive, confident engineer.  It is a long process.  Sometimes it doesn’t happen.

 

Two tasks that may keep humans in the game:

 

Quantifying Soil and Groundwater Conditions

We geotechs have an advantage; we work with heterogeneous materials.  Soil and groundwater conditions change, sometimes abruptly, between the sampling locations.  Also, when you add mixed unknown fill to the equation things become even more complicated.

This variability makes it difficult to characterize a site.  A good geotechnical engineer can use judgment to help “bridge” these data gaps.  Perhaps AI would use statistical algorithms as their “judgment.”

Perhaps Dr. Karl Terzaghi’s observational method will help keep us humans at the helm, or at least heavily involved.  When construction starts we will be needed to confirm the soil/groundwater conditions match up with the exploration results.  The initial site characterization and exploration won’t find everything. We can partner with the AI to evaluate whether changes are required to the recommendations.

It would likely be difficult to have machines perform these site observations.  It would require a blend of sophisticated robotics and programming.  I bet we will still be needed.  Do you agree?

 

Process Supervision

Geotechnical engineering can be a bit of an art form. I’ve been told that it is dark magic, black box engineering or something to that effect.  We geotechs smile at that, maybe even revel in it. 

We have many variables and initial conditions to determine.  Some of these you really have to drill down to find out (sorry can’t help a drilling reference!), such as your client motivations and needs, why the Architect is designing such a complicated structure, why the Contractor has a fast-track schedule, etc.  We can partner with the AI to understand these human needs.

 

Conclusion

AI and robots may create opportunities for geotechnical engineers and the existing and future workforce, as this CEO envisions. As retailers, manufacturers and even farms become automated, it seems as though we’ll have to keep an eye on what’s next and how we can position ourselves.  We certainly don’t operate in a vacuum, and our competitors are always pushing us.

Without question geotechnical engineering will be a different profession as time goes by.  I expect fewer people will be needed for the field and laboratory data collection areas of the business.  CAD operators will probably go by the way side.  But for the good geotechnical engineers, my hope is that we will still be behind the curtain,  pulling the strings.  

What are your thoughts? Send us your feedback[VM1] .


 

Monday
Mar192018

Leading Thoughts: 3/19/18 Ground Improvement Transcends "Aggregate Piers"

Charles Allgood, P.E. explains why “aggregate piers” is inadequate terminology to describe modern ground improvement.

Lately I’ve noticed the construction community using the catch-all phrase “aggregate piers” to describe ground improvement.  Sometimes I even hear “agg piers!” This phrase might work for old-fashioned stone columns but our industry has advanced far beyond that with many new methods and materials.

The earliest use of “aggregate pier” I can find is a December 1994 article in Civil Engineering magazine.  This article, titled “Geopiers – short aggregate piers – provide an economical alternative to over-excavation/replacement…” was written by Dr. Nathaniel Fox, PE, the inventor of Geopier®.   So perhaps that set the stage.

Now we have Rammed Aggregate Pier® systems using both drilled and displacement methods.  Rigid Inclusion systems can be constructed with cement or grout admixtures (GeoConcrete Columns or Grouted Impact Piers) and even high-density plastic confining sleeves (Armorpact® piers); these are transforming what was previously referred to as the “aggregate pier” landscape. 

Geopier Armorpact under construction

Examples of Rammed Aggregate Pier are the Geopier GP3® system and the Geopier Impact® system.  These use crushed stone so they are closer to the aggregate pier description.  The GeoConcrete® and Grouted Impact® system are two rigid inclusion methods that have little in common with “aggregate piers” other than there is some aggregate in them! 

The common denominators are: there is a suite of ground improvement techniques to choose from, some are better than others in certain soil types, and all of them allow the structural engineer to design a building for normal spread footings and floor slabs-on-grade.

I suggest that more descriptive phrases be used by the construction community.  For instance, if you have an organic soil site you probably want a Rigid Inclusion method for foundation support, not an aggregate pier. 

If you have a contaminated site then you may lean towards a displacement (non-drilled) ground improvement solution.  If you have a variable fill site you should seek a drilled aggregate pier solution to give confidence that the fill is penetrated.  Tailor your wording to the best-fit technologies. 

I understand the impulse to be generic, but if sometimes you need to say Geopier go ahead and say it!  After all we brought ground improvement to the modern day construction site.

Ground improvement is so much more than “aggregate piers.”  Specify what you really want.  Enjoy the results.

Sunday
Feb182018

Leading Thoughts: 2/18/18 Client Benefits for Geopier® Ground Improvement

We asked Jeff Christensen, P.E., Senior Engineer at Ground Improvement Engineering, about the benefits of choosing Geopier® ground improvement.

 Geopier GP3® Construction

Does your project site have poor soils? Is your project in a tight, urban location? Are you looking for ways to save time and money? If you answered “yes” to any of these questions, let the experienced Geopier team evaluate your situation.  We will tailor a solution to address your needs.

Here are the three good reasons for the Owner or Design Team to choose Geopier ground improvement:

Cost Savings

Geopier ground improvement can save you money, especially compared to expensive deep foundations (piles, caissons, etc.) or over-excavation and replacement.

In the case of deep foundations we can help you switch back to normal footings and floor slabs-on-grade.

The cost of removing poor soils, trucking them offsite and importing select fill can be daunting. How about trying to dry the soils onsite for reuse?  A couple of rainy weeks will stop you in your tracks.

Dewatering or temporary shoring to protect existing buildings or utilities can add up, too. Why not improve the unsuitable soils in place to make things easier on your wallet? 

Smaller Footings

Geopier techniques create very stiff improved conditions for high soil bearing pressures. Smaller footings have less concrete, less reinforcing steel and require less labor, again putting money back in your project for other items.

Faster Schedules

We expect that you want to finish the project quickly and before the completion date. We can help with that by getting the work done quickly; often you can start foundations while we are still on the site.

So, what are you waiting for?  We can evaluate your project quickly and give you a budget that is realistic.  You have engaged a team that includes engineers and licensed contractors that have completed more than 8,000 Geopier ground improvement projects.  Now that is a lot of improved soil experience!

 

Contact our geotechnical engineers. Improve your site and put the savings to better use.