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CONTENTS
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THE COVER Underground Art Scene: Updating the Museum of Fine Arts, Houston – story on page 10 CHANNELS STRUCTURES + BUILDINGS 12 Supporting the Bottom Line: High-Performing, Engineered, EPS Geofoam as an Alternative Fill 14 Ground Improvement 17 Fermilab – Integrated Engineering Research Center 19 UMA Supports South Carolina Manufacturer's Expansion with Micropiles TRANSPORTATION + INFRASTRUCTURE 23 High-Temperature Tunnel Dampers and Switchboxes Are a Hot Combination for Riyadh Metro System 25 Invisible Enemy 27 Colesman Tunnel 29 Automation and Digitization Enabling Informed Decision Making Throughout the Tunneling Lifecycle WATER + STORMWATER 32 Land & Water Completes Sustainable Works as Part of the Thames Tideway Tunnel Project 34 Light at the End of the Tunnel: How Technical Innovation and Community Buy-in Turned a 5.6 km Microtunnelling Project into a Huge Success BUSINESS NEWS 37 5 Keys to Designing Earthquake-Resistant Buildings 38 Coming Soon: Practical BIM Implementation for Facility Management SOFTWARE + TECHNOLOGY 39 The Collaboration and Constructible Models Behind HUS Helsinki University Hospital’s Largest Project 40 Arcadis Deploys Autodesk Cloud Technology to Deliver an Infrastructure Project Bookended by Public Health Crises UNMANNED SYSTEMS 42 Taking UAV Technology Even Higher SURVEYING 43 Precise Accuracy for Underground Pipelines 45 California Company Uses New GPR Technology for Underground Utility Locating 47 Three Ways Your Surveying Practices Might Be Falling Short departments 8 Events 49 Benchmarks: How long does it take to fill an open position in the AEC industry? 50 Reader Index Columns 5 From the Publisher: Tunnel to Safety Chad Clinehens 6 Engineering Front Line: Purpose Driven Leadership and Strategy Phil Keil
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VOLUME 7 ISSUE 3 csengineermag.com
publisher Chad Clinehens, P.E. | 479.856.6097 | cclinehens@zweiggroup.com media director Christy Zweig | 479.445.7564 | czweig@zweiggroup.com Production & circulation manager Anna Finley | 479.435.6850 | afinley@zweiggroup.com ART director Maisie Johnson | 417.572.4561 | mjohnson@zweiggroup.com Editor Luke Carothers | lcarothers@zweiggroup.com
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CIVIL + STRUCTURAL ENGINEER IS A ZWEIG GROUP PRODUCT
MARK C. ZWEIG, CHAIRMAN, ZWEIG GROUP LLC
Civil + Structural Engineer (ISSN 23726717) is published monthly by Zweig Group, 1200 North College Avenue, Fayetteville, AR 72703. Telephone: 800.466.6275. Copyright© 2020, Zweig Group. Articles not be reproduced in whole or in part without the written permission of the publisher. Opinions expressed in this publication are not necessarily those of Zweig Group. Unsolicited manuscripts will not be returned unless accompanied by a stamped, self-addressed envelope. Subscriptions: Annual digital subscription is free. To subscribe or update your subscription information, please visit our website www.csengineermag.com/ subscribe/ or call 800.466.6275.
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from the publisher
As I was nearing graduation in 1999 and finalizing where I would start my first full-time job as an engi- neer intern, I traveled to Little Rock, Arkansas to interview for the transportation team of an Arkansas- based engineering firm, where I would ultimately start and spend the majority of my career. On that jour- ney, I left the college town of Fayetteville and traveled interstate 540, now I-49, which had just opened weeks before. I-49 is an approximate 40-mile section of interstate that bypassed US-71, once known as one of the most dangerous highways in America. The opening of I-49 was a huge event for Northwest Ar- kansas as it dramatically improved accessibility to the south, connecting Northwest Arkansas to I-40, one of the major east-west interstates in the United States. Probably more importantly, it improved the safety of a rapidly increasing population in Northwest Arkansas where travel in and out of the area was essential to the growing commerce. As a kid, I remember traveling highway 71 and seeing the large flashing signs as you would leave Fayetteville saying “16 people killed in the last 3 years. Use extreme caution while traveling” or something similar. If you asked my mom what the opening of I-49 meant for her as I made my first trip to Little Rock on that new, much safer I-49, she would say she slept much better at night. There was another first for me on my maiden voyage to Little Rock in 1999, it was the first time I had driven through a tunnel. One of the reasons the $458 million alternate route took so long to come to frui- tion, was the incredibly challenging topography of the project. The 40-mile stretch of interstate has some of the tallest interstate bridges west of the Mississippi River, traversing some extreme peaks and valleys. One of those peaks was an 1,800-foot high section that was ultimately tunneled through. The neat part for me as a civil engineer was the firm I was going to interview with on that day in 1999, Garver, was the firm that was awarded the tunnel feasibility study back when I-49 was just a conceptual plan. The study determined that a tunnel was the best option as alternatives would spoil the topography and require too much cut. The result was the Bobby Hopper tunnel, the first and only interstate tunnel in Arkansas. With two bores at 1,595 feet long, 38 feet wide and 25 feet tall, interstate traffic enters the mountain effortlessly with plenty of space in the tunnel including shoulders. When I drove through the tunnel, it was not the first time I had been in those tunnels. During construction, I was part of a tour group with the Arkansas Society of Professional Engineers (ASPE) and we were able to go inside the tunnels as they were progressing through the mountain. Getting access to the site was extremely difficult, but once we got there it was a fascinating experience. We toured the tunnels when they were about 40 percent through the mountain. I remember a lot of mud. The tunnels were mined, not bored, through the moun- tain. Blasting, drilling, and excavation removed native shale and sandstone rocks, which is very prevalent in the area. Had this been during the cell phone camera era I would have plenty of pictures to share, but instead, all I have is memories. Since then, I’ve been fascinated by tall bridges and tunnels. These epic projects take years and often decades to finish, but once complete, provide access and safety for generations. Last year, right before the pandemic began, I was fortunate to get to ride the Eurostar train from Paris to London. The Channel Tunnel, also known as the “Chunnel”, is a 32-mile railway tunnel under the English Channel at the Strait of Dover. At 380 feet below sea level, traveling 100 mph in the longest underwater tunnel in the world is an exciting experience for a civil engineer. For us civil and structural engineers, along with the many other related professions that design build the world, we have a lot to be proud of. We give access to new areas of the world. We provide new oppor- tunities for commerce and growth. We provide great experiences. We connect people. We empower the world. What an awesome profession we’ve dedicate our lives to. It all started for me when I traveled that stretch of roadway and that tunnel that had just opened up weeks before. The civil and structural engineers, along with the geologists, surveyors, contractors and beyond spent over 10 years making that new connection possible. What it meant to me was that my mom would sleep better at night knowing the many trips on I-49 that started with that job interview, would be safer and easier.
Tunnel to safety
Chad Clinehens
CHAD CLINEHENS, P.E., is Zweig Group’s president and CEO. Contact him at cclinehens@zweiggroup.com.
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Purpose driven leadership and strategy Phil Keil
To solve the problem of soul-destroying traffic, roads must go 3D, which means either flying cars or tun- nels are needed. It is December 2016, and a new company emerges that constructs safe, fast-to-dig and low-cost trans- portation, utility, and freight tunnels, The Boring Company created by Elon Musk. Love him, hate him, agree with him, or not, Elon Musk has accomplished some incredible things, including adding $165.5 billion in wealth in the past year, which means we should at least learn something from him. He clearly isn’t driven by the money, though. According to the man himself, the thing that drives him is his vision: “I think it’s important to have a future that is inspiring and appealing. There has to be reasons you get up in the morning and want to live. Why do you want to live? What’s the point? What inspires you? What do you love about the future?” — Elon Musk “When something is important enough, you do it, even if the odds are not in your favor.” — Elon Musk What is incredible to me, personally, is that when he cares about something, he goes out and finds a solution and does it. This is clearly evident on the climate front and Tesla being recognized as a purpose- driven innovator breaking records in sustainable transportation, technology, and more. Musk clearly has missions with associated companies rather than companies with associated missions. He builds move- ments, elevates the brand, and democratizes the impact. His organizations break down barriers and de- molish silos with flat organizations, ensures everything they do is aligned with the mission, and focuses on continuous improvement. This is incredibly important for anyone to understand. You need to have purpose driven leadership throughout the organization which informs your strategy development and ultimately allows you to build a legacy. It is hard to overstate the impact of following this advice and I’ll share some numbers with you on why that is the case. I will not sugarcoat it, though, this is a much more difficult task to authentically implement than it is to state here. Purpose and profits are not fundamentally opposed to each other. This has been demonstrated empiri- cally by research conducted through the Wharton School of Business, Harvard University, and The Great Places to Work Institute. They used more than 1.5 million employee-level observations across thousands of companies and quantified purpose as the aggregate sense of meaning and impact felt by employees of a corporation. If a company has a strong corporate purpose, its employees will feel greater meaning and impact in their jobs. In the data, companies with a high level of purpose outperform the market by 5-7 percent per year, on par with companies with best-in-class governance and innovation capabilities. They also grow faster and have a higher profitability. This, however, is only successful if senior level manage- ment can successfully infuse that purpose throughout the organization and especially the middle manage- ment. This outcome is also supported by the performance of the winners of Zweig Group’s Best Firm to Work For Award. While a higher purpose does not guarantee economic benefits, the Gartenberg study, which included 500,000 people across 429 firms and involved 917 firm-year observations from 2006 to 2011 suggests a positive impact on both operating financial performance (return on assets) and forward-looking measures of performance (Tobin’s Q and stock returns). Therefore, we are not simply discussing a lofty ideal, but one that has practical implications for your firm’s financial health and competitiveness. This can be trans- formational for your organization. Below, you will find an 8-step framework that can help you overcome the “transactional” view of employee motivation (i.e., compensation and pay). 1. Envision an inspired and motivated workforce 2. Uncover your purpose 3. Make sure you are authentic 4. Communicate the message constantly 5. Stimulate individual learning 6. Turn mid-level management into purpose-driven leaders 7. Connect your people and behaviors to the purpose 8. Unleash the positive power of the entire firm through typically unrecognized change agents As always, we enjoy hearing from you. Tell us what you think and get in contact with us if you’d like our help in putting these ideas into practice.
PHIL KEIL is director of Strategy Consulting, Zweig Group. Contact him at pkeil@zweiggroup.com.
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Online Learning Opportunities KEEP YOUR CAREER DEVELOPMENT A PRIORITY
VIRTUAL SEMINARS
Elevating Doer-Sellers: Business Development for AEC Professionals – VIRTUAL SEMINAR DATE: April 6, 2021 PRICE: $699 PDH/LU: 6 Credit Hours OVERVIEW: This will be the same great content that is taught during our in-person The Principals Academy seminar that has trained over 900 attendees in the last five years. The Principals Academy is Zweig Group’s flagship training program encom- passing all aspects of managing a professional AEC service firm. Elevate your ability to lead and grow your firm with this program designed to inspire and inform existing and emerging AEC firm leaders in key areas of firm management leadership, financial management, recruiting, marketing, business development, and project management. LEARN MORE
Project Management for AEC Professionals – VIRTUAL SEMINAR DATE: April 7, 2021 PRICE: $699 PDH/LU: 6 Credit Hours LEARN MORE
OVERVIEW: Each team member brings their own unique experiences and skillset to project teams. Effectively leveraging the talents of your team can optimize team effec- tiveness. This course provides people-focused, science-driven practical skills to help project leaders harness the power of their team. By addressing the most important aspects of any project – the people – this course will provide practical techniques that can be immediately implemented for a positive impact on any AEC team or business.
The Principals Academy – VIRTUAL SEMINAR DATE: May 4, 2021 PRICE: $999 PDH/LU: 12 Credit Hours LEARN MORE
OVERVIEW: This will be the same great content that is taught during our in-person The Principals Academy seminar that has trained over 900 attendees in the last five years. The Principals Academy is Zweig Group’s flagship training program encom- passing all aspects of managing a professional AEC service firm. Elevate your ability to lead and grow your firm with this program designed to inspire and inform existing and emerging AEC firm leaders in key areas of firm management leadership, financial management, recruiting, marketing, business development, and project management.
VIEW ALL ONLINE LEARNING OPPORTUNITIES
Zweig Group is an approved provider by the American Institute of Architects (AIA).
events + virtual Events
March 2021
structures congress 2021 march 10-13 – seattle, wa
As a structural engineering professional, you can find the latest information, innovation, products, and technology at Structures Congress. Learn best practices to push the boundaries of structural design, and bring back new ideas to improve your practice, help clients problem-solve, and be more innovative. Join us to experience all that SEI/ASCE offers to lead and innovate in Structural Engineering. Interact with and learn from the experts on Blast, Bridges, Buildings, and more, and earn Professional Development Hours (PDHs). https://www.structurescongress.org/
AM Industry Summit Collective Intelligence for AdditiveManufacturing march 2 – virtual Cross-industry collaboration provides fresh perspective and collective intelligence to transformobstacles intoopportunities and forgenewpaths. AM Industry Summit connects like-minded Additive Manufacturing & 3D Printing professionals in industries to address common challenges and discover opportunities. These landmark events are helping to foster a true knowledge across industry of 3D technologies’ potential. https://event.asme.org/AMIndustrySummit This advanced project management course is designed to take a Project Manager to the next level, with a focus on anticipating problems, communicating with leadership and other important stakeholders, and transitioning frommanaging to leading people and projects. It will focus on the nuances of different situations that commonly arise and how to adapt and optimize your responses to situations in order to maximize the impact of core PM skills. This will address ways to change your approach to be more effective in leading projects in greater magnitude of budget and importance and discuss precision in communication. This course features elements not offered in any other project management course, including being led by an industry expert with almost two decades of project management experience, and two psychologists with expertise in people skills, behavior change, group dynamics, and implementation science. Advanced Project Management for AEC Professionals march 3 – virtual https://shop.zweiggroup.com/collections/webinars/products/advanced- project-management-for-aec-professionals-virtual-seminar-starting- february-3-2021?variant=38779399635095 Damage caused by de-icing salts, known as salt-scaling, is a major contributor toward repair costs related to transportation infrastructure. Such damage consists of the removal of small chips or flakes of material at the exposed surfaces of concrete elements. To increase the service life of slabs on grade and reduce potential damage caused by salt- scaling, it is necessary to know the characteristics of salt-scaling and to understand parameters that could be used to control such damage. However, despite extensive studies, many details regarding salt-scaling are still not fully understood, and contradictions within the literature can be confusing. The aim of this presentation is to help better understand the salt-scaling phenomenon and provide insights into the effect of workmanship, mixture parameters, and concrete hardened properties on salt-scaling resistance of concrete. https://www.concrete.org/store/productdetail. aspx?ItemID=W2103&Format=ONLINE_LEARNING&Language=E nglish&Units=US_Units An Overview of Salt-Scaling Damage march 3-4 – virtual
Knackathon 2021 march 15 – dallas, tx & virtual
TheKnackathon ethos ofmentorship drives our vision for the conference. Each team includes engineering pros working alongside high school and college students. Teams are judged based on their technical deliverables as well as their decidation to mentorship, diversity, and inclusion. https://knackathon.org
ACI Virtual Concrete Convention march 28-april 1
With more than 2,000 attendees, the ACI Concrete Convention combines the brightest minds in concrete with an unparalleled social environment, bringing a premiere event to concrete professionals to collaborate and advance the industry and their knowledge. https://www.concrete.org/events/conventions/currentconvention. aspx?&utm_campaign=s21virtual_jan7&utm_medium=email&utm_ source=press_release april 2021 We are just years away from reaching our goal of graduating 10,000 Black engineers annually by 2025. That means it’s time to take a holistic approach at developing the next generation of engineers and enhancing the NSBE experience for all. We are excited to introduce to you NSBE47: The Holistic Engineer – hosted virtually to bring together a showcase of the best of our talent, treasures, and more. https://convention.nsbe.org/ NSBE 47th Annual Convention april 5-9 The concept of living buildings has recently emerged as the new ideal for sustainable building design and construction. Defined as a building that generates all of its own energy with renewable, non-toxic resources, captures and treats all of its water, and operates efficiently with an uncompromising aesthetic, living buildings represent a new species of buildings that blends boundaries between the built environment and the natural world and necessitates creative, integrative engineering and architecture solutions to meet rigorous design challenges. https://www.aei-conference.org/ aei conference april 7-9
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May 2021
september 2021 Commercial UAV Expo Americas september 7-9 – las vegas, nv
AUVSI XPONENTIAL may 3-6 – atlanta, ga & virtual
At the world’s largest (virtual) event for unmanned and autonomous systems, you’ll find your momentum, that something extra that gives you a competitive edge – your X factor. https://www.xponential.org/xponential2020/public/Content. aspx?ID=3662&sortMenu=107001
Commercial UAV Expo Americas 2021 is where the commercial drone community gathers to learn, connect, and drive the industry forward. In addition to content about new opportunities and challenges the industry is facing due to COVID-19, industries covered include Construction; Drone Delivery; Energy & Utilities; Forestry & Agriculture; Infrastructure & Transportation; Mining & Aggregates; Public Safety & Emergency Services; Security; and Surveying & Mapping. It is presented by Commercial UAV News and organized by Diversified Communications. https://www.expouav.com/ ENGINEER is the newest trade exhibition presented by C.I.S jointly organised with Malaysia’s official professional organisation for the engineering fraternity – The Institution of Engineers (IEM). This industry trade event is aimed towards providing engineering professionals in Malaysia and the region with an exciting and unique platform to gain an insight into cutting-edge solutions and advanced engineering technologies by international leading manufacturers. ENGINEER offers invaluable opportunities to network, collaborate and exchange ideas over the four-day event. https://engineermalaysia.com.my/ ENGINEER 2021 september 8-11 – malaysia The International Association for Bridge and Structural Engineering (IABSE) is a scientific/technical Association comprising members in 100 countries and counting 56 National Groups. The aim of the Association is to exchange knowledge and to advance the practice of structural engineering worldwide in the service of the profession and society. Founded in 1929, IABSE hosted a series of Congresses every four years from 1932 to 2016 and every year from 2019. https://iabse.org/ghent2021 IABSE Congress Ghent 2021 september 22-24 – ghent, belgium
Drone XPO may 26-27 – ExCel, London
Drones are transforming the processes of many sectors and improving safety. More and more companies are using drones for different purposes. At the DroneX Trade Show & Conference you can reimagine the possibilities of unmanned vertical flight, and take a first-hand look into the latest technological advancements. https://www.dronexpo.co.uk/ june 2021 A robotics competition held during the automatica trade fair every two years, as part of munich_i, to showcase state-of-the-art methods in robotic manipulation. This year, the Robothon® will take place at automatica sprint 2021 as a special solution regarding the current situation. Selected teams of roboticists from academic and professional spheres will converge to solve a modern day manufacturing grand challenge in a multi-day competition. https://www.robothon-grand-challenge.com/ Robothon june 22-24 – munich, germany & virtual From drone delivery to driverless cars, automated mobility provides limitless opportunities and very real challenges. Join AUVSI and SAE International for the inaugural Business of Automated Mobility (BAM) Forum for tactical insights to get your business on the path to profitability. https://www.bam-forum.org/register july 2021 business of automated mobility forum june 23-24 – munich, germany & virtual CEAD Germany 2021 will make an ideal stage for worldwide, as it unites famous speakers, specialists, business people over the globe, with a generally energizing and important logical occasion loaded up with a lot of edifying intuitive sessions, world-class display, Oral and publication introductions. Civil engineering conference 2021 show’s a goal to furnish the development, business with a profoundly engaged entryway to learn, arrange, and exploit the significant developments and Learning. https://ic2020cead.org/ International Conference on Civil Engineering and Architectural Design july 1-3 – munich, germany
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The old saying is true when it comes to the Museum of Fine Arts in Houston (MFAH): everything is bigger in Texas. One of the largest museums in the United States, MFAH services the fourth largest city in the country, with its wide array of programs being utilized by a stag- gering 1.25 million people every year. The oldest museum in the State of Texas, it was first constructed in 1917 and in 1924 it allowed its first visitors through the doors. Since then, the site has seen its fair share of construction. MFAH has recently undergone renovations in the way of new building construction. In December 2020, construction was completed on the Nancy and Rich Kinder Building on the MFAH campus. The project was split into two phases with the first focusing on construction of the 102,500 square foot Glassell School of Art; this phase nearly doubled the space available for the school, which currently serves 7,000 stu- dents per year. The teaching arm of MFAH, this space allows the Glassell School of Art’s students to access fully digital workspaces and classrooms as well as expanded exhibition space. This space replaces the previous building that housed the school since 1979. Phase two of the project consisted of the construction of the Nancy and Rich Kinder Building, a 183,500 square foot exhibition space to house modern and contemporary art made after 1900. The building features a translucent glass cool jacket exterior, three-floors of galleries circling a three floor atrium, a 225-seat theatre, a street-level cafe, a restaurant overlooking the sculpture garden, an underground parking garage with 115 spaces, and tunnels connecting the building to both the Glassell School of Art as well as the Caroline Weiss Law Build- ing. When completed, this building increased exhibition space at the MFAH by 75 percent. One of the more interesting aspects of the project was the construction and utilization of an underground tunnel that connects the new building to the older parts of the campus. The plan was to create a 150-foot tunnel to connect the Nancy and Rich Kinder Building to the Caroline Wiess Law Building. This tunnel, while primarily designed to facili- tate pedestrian traffic between the buildings, also serves a gallery space for the MFAH. The building site itself included a number of unique obstacles that required the team at McCarthy to come up with creative solutions and utilize innovative techniques to complete the project. Plans for these tunnels had to account for several challenges that are posed by the site’s unique human environment. Being located in one of the oldest parts of the city of Houston, this meant that there was a possibility the team would encounter an unmarked, buried utility line. Underground Arts Scene: Updating the Museum of Fine Arts, Houston By Luke Carothers
Winston Hesch, project director for McCarthy, says ground utilities in this part of town can “sink over time”. Additionally, because the tunnel is located 2-3 feet underground, engineers had to waterproof the site not only for rainwater, but also for ground water. Typically, tunnelling in the Houston-area is done a particular way: a trench is dug then a cover is added, thus forming a tunnel. However, because the City of Houston would not allow the team to close Bis-
Project Contributors McCarthy Building Companies– General Contractor and Concrete Subcontractor AR Daniels– Tunneling Specialist Contractor Chamberlin Roofing and Waterproofing– Waterproofing Hayward Baker– Shotcrete
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sonnet Street for an extended period of time, as well as un- derground utilities, the team opted for a different, more traditional route: excavating the tunnel six inches at a time. This process proved time con- suming, taking the team six and a half months to complete while excavating the tunnel six inches at a time. Addi- tionally, in order to connect the two buildings, the tunnel had to change in elevation and offset horizontally. In order to achieve these parameters while also keeping a shape with a curved top, straight sides, and flat bottom the team opted to install a series of interconnected plates ap- proximately every six inches of excavating. To support this plate system, the team installed an I-beam approxi- mately every six feet and in- jected the system with grout.
Challenging this process was the high presence of water at the site. The team had to deal not only with rainwater, but also groundwater as the tunnel was constructed close to the water table in the area. They were able to overcome these challenges by using PREPRUFE 400T, which is a Grace Waterproofing Project. In order to account for the
thousands of anchor bolts being drilled through the waterproofing ev- ery day, McCarthy’s team met with manufacturers to come up with a plan of action. The result was a hand check of every seam and penetra- tion of the system to ensure proper installation. Once the system was fully completed, the team encountered no leaks. The months of excavating and tedious checking have paid off. Unlike most tunnels, this project has systems like mechanical, electrical, and lighting installed. More than just a pedestrian walkway and art gallery, the space and project have become a work of art of themselves, adding yet another dimension and element to one of the most storied public institutions in Texas.
LUKE CAROTHERS is the Editor for Civil + Structural Engineer Media. If you want us to cover your project or want to feature your own article, he can be reached at lcarothers@zweiggroup.com.
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Expanded polystyrene (EPS) Geofoam (GF) is a rigid, engineered fill material that is widely known for its lightweight composition, predict- able performance, and simplified installation process. The effective fill solution is frequently employed by engineers and project designers to optimize labor resources, speed up construction timelines, and address a variety of geotechnical challenges, including: Supporting the Bottom Line: High-Performing, Engineered, EPS Geofoam as an Alternative Fill By Tom Savoy • lightening loads on structures, utilities, or underlying soils • remediating soft soils and minimizing differential settlement • stabilizing steep slopes and embankments • reduce lateral load behind retaining structures • serving as a structural void fill for concrete or landscaping applications EPS GF has been used as a geotechnical material since the 1960s. One of the first documented projects in North America that utilized EPS GF was during the installation of the Trans-Alaska Pipeline. Thanks to its thermal insulation properties, EPS GF was employed to provide effective utility protection. Decades later, it’s still being successfully utilized in the field. Just a few years ago, the rigid foam material was used to accelerate construction timelines and effectively stabilize the eastbound lanes of U.S. 36 between Boulder and Denver, Colorado. The material’s lightweight composition made it possible for crews to quickly unload over 200 flatbed trucks and install the product with ease. More recently, engineers and architects utilized EPS GF to build up a quarter-mile bridge across Tampa Bay that leads to the newly renovated St. Pete Pier waterfront park on Florida’s West Coast. The lighter load reduces settlements and boosts stability against bearing and slope failures to successfully support the largest waterfront park in the Southeast region. Project cost-savings, galore In application, EPS GF’s combination of lightweight yet load-bearing properties can support overall project cost-savings. For example, the geosynthetic fill’s lightweight composition lends a quick, ef- ficient installation process, which in turn can reduce hours spent on the jobsite. While lightweight, the rigid foam material is engineered to demonstrate exceptional compressive resistance to support high loads. With this level of brawn, one flatbed of custom-made EPS GF can accomplish what would otherwise require approximately 12 dump truck loads of soil fill. Less material in play helps simplify construction logistics, minimizing labor and material costs in twofold. Thoughtfully engineered to maximize efficiencies, EPS GF’s lightweight composi-
Geofoam swimming pool
tion, compressive strength and customization capabilities can support generous cost-savings across a project’s bottom line. Lightweight performance Adefining feature of EPS GF is its lightweight composition. Composed of 98 percent air voids by volume, EPS GF weighs approximately 0.7 to 2.85 pounds per cubic foot. It’s approximately 100 times lighter than most soil types, and 20 to 30 times lighter than concrete. This extreme difference in unit weight is the defining feature of EPS GF, making it an attractive solution over traditional fill materials. Because EPS GF is so lightweight, large earthmoving equipment is not required during in- stallation. Instead, custom-cut blocks of EPS GF can be installed easily and efficiently by hand—an ideal solution for accelerating construc- tion schedules. Because the pieces of rigid foam are designed to lock in place, much like stacking blocks or assembling a puzzle, smaller crews are freed up to focus on other, more time-consuming tasks on the job site. In application, the material helps keep projects on budget by decreasing upfront material costs and reducing the number of hours crews spend on the job site. As mentioned earlier, EPS GF’s lightweight composition was a defin- ing feature for the St. Pete Pier project engineers and designers, who were able to apply 700,000 board feet of the rigid foam material across the concrete deck of the bridge. Because the material is so lightweight, there is significantly less stress applied to the underlying substrate. “It’s a quarter-mile deck over water, and you don’t want additional weight over water,” said Dave Hall, a territory manager for Insul- foam, the leading manufacturer of EPS products. “Ground with soft soil makes building construction notoriously difficult. If you place something heavy on soft soil, it will place pressure on the underlying soil. The soil will inevitably compress with time, putting the structural integrity of the system at risk.” To its benefit, lightweight blocks of EPS GF can sideline this problem and lighten the load on the substrate. What’s more, the material is also designed in such a way that it does not degrade—a key factor to with- standing Florida’s low sea levels and high precipitation rate. Strength to boot Although lightweight, EPS GF is designed to exhibit exceptional strength. As an engineered material, manufacturers can customize EPS
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St. Pete Pier
separate concrete pours for vertical wall sections and topping slabs. EPS GF can also be tailored to accommodate intricate landscaping features or utilities around the pool deck. This level of customization eliminates much of the field-cutting, which again supports material and labor cost-savings. Final thoughts While traditional fills have, and likely will continue to have their place across civil and structural applications, EPS GF offers engineers and project designers an efficient, cost effective fill alternative. The rigid foam material enables professionals to design by function, that is, to focus on addressing key geosynthetic challenges within a particular project. The material exhibits several special characteristics—a light- weight composition, compressive strength and easy customization— that truly sets it apart from traditional fill options. This inherent multi- functionality replaces the need to employ a host of building materials and tools to achieve project goals. Because EPS GF takes the “less is more” approach to address void fill needs, it can support generous labor and material cost-savings—keeping project budgets in the black.
St. Pete
GF blocks to offer enhanced compressive strength, with values ranging from approximately 2.2 psi to 18.6 psi (317 to 2,678 pounds per square foot) at a 1 percent strain. Assuming combined dead/live loads do not exceed the 1 percent strain designation, the material will not creep or experience plastic yield. With this assurance, EPS GF offers improved stability against bearing and slope failures. And, because the material is engineered to disperse loads evenly across a surface, it minimizes post- construction settling, which again supports a more stable foundation. This is not the case with soil and related fill materials, as their incon- sistent compositions can lead to non-uniform load transfer and differ- ential settlement. This can cause dangerous, uneven settling and lead to permanent structural damage. By employing the EPS GF approach, engineers and project designers will proactively avoid these risks and ultimately extend the lifespan of the complete building system. Superb customization Although EPS GF can be manufactured in many sizes and shapes, standard blocks are typically 40" x 48" x 96". These oversized puzzle pieces can fill massive volumes, reducing upfront material and labor costs. For custom projects, the rigid foam material can be cut on the factory floor to meet exact specifications. For example, engineers and project designers can use EPS GF to simplify the construction of commercial and institutional swimming pools. The blocks of material can be pre-cut to create virtually any shape or slope, which eliminates
TOM SAVOY is the technical director for Insulfoam, a division of Carlisle Con- struction Materials. He has worked in the EPS Industry for 34 years and in construction materials (manufacturing and testing) for 40 years. Tom actively participates in many trade organizations including ASTM, SPRI and EPS IA. He can be reached at tom.savoy@insulfoam.com.
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Ground Improvement By Martin G. Taube, P.E., P.G. and Sonia Sorabella Swift, P.E.
Historically, when building on sites with poor soils, builders had two primary options to choose from – piling and removal and replacement. While some ground improvement techniques such as dynamic com- paction have origins tracing back to the middle ages, it wasn’t until the past half century that ground improvement began to gain wide ac- ceptance and recognition as a viable option for addressing sites with problematic soils. The last few decades have seen a proliferation of the types of ground improvement techniques, installation methods, equip- ment capabilities, design methodologies, QA/QC requirements and procedures, and number of contractors offering ground improvement. At many sites, excavating the problematic soils and importing and compacting fill is a viable solution. However, removal and replacement has its limitations, particularly when the problematic layers extend be- yond a few feet. Where groundwater is high and deeper excavation is required, it may be necessary to dewater or install groundwater barriers such as cutoff walls or sheet piling. It may be necessary to protect adjacent structures by underpinning or with support of excavation sys- tems. Deeper removal and replacement becomes very costly and cause schedule issues, especially when faced with preparing subgrades and placing fill in wet or frozen conditions. And of course, the prospect of unearthing contaminated soils or buried hazardous materials will strike fear in any developer or property owner. Most civil and structural engineers are very familiar and comfortable with multiple types of piles and other deep foundation elements since these systems have traditionally been the default foundation systems for sites with problematic soils. These systems are tried and true, but are they always necessary? In many cases, ground improvement can result in savings by both eliminating deep foundations and allowing structures to be supported on shallow foundations systems, as if you were building at a site with competent soils. To select the appropriate type of ground improvement for a site, it is important to understand what challenges the ground may pose for the support of the structure. Could excessive settlement occur due to soft or loose soils? Is the factor of safety against bearing capacity failure too low due to the presence of weak layers? Are slopes or embank- ments unstable? Would excessive differential settlement occur due to differential loading conditions or variability of soil conditions across the site. Is undocumented fill or buried debris present at the site? Is liquefaction a risk at the site? With all the potential issues that sites may face, the importance of a thorough geotechnical investigation can- not be overstated. To allow for the selection of the appropriate ground improvement system, and its optimization, it is critical that sites are characterized with sufficient coverage (and depth) of borings or sound- ings, and with ample laboratory testing to determine the characteristics and strength properties of the on-site soils. Another vitally important aspect of ground improvement selection and design optimization is having a good understanding of the layout and ac-
tual loads for the proposed structure. In some cases, the highest building column loads are adapted as the design case for the entire structure – this results in an inefficient ground improvement design. Optimization of ground improvement comes from a deeper understanding – of the site, of the ground, and of the structure. There are many different ground improvement systems adaptable to a wide array of site conditions, soils, and structure types. In general terms, there are three typical modes of soil improvement – densifica- tion, reinforcement, and drainage enhancement. Some systems provide Rapid Impact Compaction (left) and Dynamic Compaction (right) are used to densify fill material to accommodate building construction at a site in New Jersey.
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one of the modes of improvement, while other systems may provide two or three of the modes of improvement. Densification is used to improve granular soils such as sand or gravel and is typically achieved by imparting vibration into the ground to prompt the granular soil grains to rearrange into a denser state. Den- sification can also result from the displacement of granular soils by elements that are drilled, vibrated, or grouted in place. Densification, also referred to as compaction, reduces compressibility, and increases shear strength, leading to improved bearing properties and reduced settlement of the treated soils. Reinforcement is achieved by installing relatively stiff elements within soft, weak, or variable layers. The elements typically are installed by drilling, vibrating, or driving a casing or probe and filling the resultant void with grout or compacted stone to form a column. If the receiv- ing ground is granular, densification of the surrounding ground is a corollary benefit of the installation for elements that are installed with displacement methods or during compaction of the stone column. Soil preloads have long been used as a simple, economical method for preparing sites. In the simplest terms, a preload consists of a pile of soil that exerts stresses on the receiving ground that are similar or greater than the stresses that the ground will receive from the planned structure. As the preload remains in place, the underlying soil layers are squeezed and compressed. Where saturated clay layers are present, it can take months, years, or even decades for the consolidation to occur due to the lower permeability of clays. Keeping a preload in place for more than a few months is typically not practical. Vertical drains are commonly installed to expedite consolidation drainage in conjunction with preloads and also under fills, berms, dikes, levees, and reclaimed land. Common Ground Improvement Techniques Densification, reinforcement, and drainage enhancement can all be used to increase bearing, reduce total and differential settlement, in- crease shear resistance, and to mitigate liquefaction. Selection of the appropriate technique or combination of techniques is done on a case- by-case basis, and dependent on the geotechnical conditions, depth of problematic soils. the configuration and layout of the structure, loading conditions, settlement criteria, construction schedule and sequencing, size and location of project, and site access. Following are brief de- scriptions of some of the more commonly used techniques being used Dynamic compaction uses large crawler cranes to drop weights that typically range from 10 to 20 tons repeatedly in a predetermined grid pattern to increase density and reduce voids in granular soils, fills, and landfill materials. Most effective for large-footprint sites, the tech- nique is less effective in overly clayey or silty soils and where shal- low groundwater is present. Because of the large amount of vibration introduced into the ground, special care should be taken when using dynamic compaction near utilities, buildings, or other vibration- or settlement-sensitive structures. A related technique, Rapid Impact Compaction (RIC) is used to compact soils when it is necessary to in the United States today. Dynamic Compaction
limit vibrations. RIC typically treats a shallower depth of soil and is performed using a pile-driving hammer that is mounted to the front of an excavator to pound a steel plate seated on the ground surface. Vertical Drains Wick drains are thin, flexible drains that typically measure 1/8-inch thick by 4-inch wide. The drains consist of a channelized plastic core encased in a geosynthetic filter fabric designed to let water in and keep soil particles out. The drains, typically spaced between 3 ft and 8 ft in a grid pattern, are pushed into the ground and can be installed to depths of well over 100 ft. Wick drains are used to alleviate excessive pore pressure that would build up in fine-grained soil layers when fill is placed, and act to speed up consolidation settlement; reducing the time necessary for soil preloads to stay in place, mitigating long term settle- ment of fills, and enhancing stability of embankments as construction progresses. To perform as intended, an outlet for the water flowing from the wick drains is necessary – this is typically in the form of a granular drainage blanket installed at the ground surface prior to wick drain installation. General depth of application for various ground improvement techniques
Four drills installing Controlled Modulus Column (CMC)TM Rigid Inclusions to improve ground for a very large distribution center in South Dakota.
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When rigid inclusions are installed with displacement drilling tech- niques, the soil is displaced laterally, with virtually no vibration or spoil, eliminating the need to dispose of contaminated soil. The auger is screwed into the soil to the required depth increasing the density of the surrounding soil and increases its bearing capacity. During auger extraction, grout is injected under light pressure to build the column to stiffen and treat the surrounding soil. Driven casing methods are also sometimes used to install the elements. Rigid Inclusions are designed as a composite ground improvement system where the column rein- forcements and the surrounding soil share the loads. Rigid Inclusions have proven to be extremely versatile in treating a wide variety of soil conditions, including very soft, compressible lay- ers, very deep layers (rigid inclusions have been installed to depths of over 150 ft) and contaminated soils, since spoil generation is minimal. Unlike pile foundation systems, rigid inclusions are not typically con- nected to foundations. A layer of compacted stone referred to as a load transfer platform (LTP) is typically installed above the Rigid Inclusion elements to help distribute the load from the structure to the underlying soil and Rigid Inclusion elements. The LTP allows for shallow founda- tions to be designed and eliminates the need for pile caps, grade beams, and structural slabs. Conclusions While this article does not cover every ground improvement technique that is available, it highlights a wide range of techniques available to treat a variety of problematic soil conditions. Ground improvement systems are intended to be elegant in their simplicity, and are used to support any number of structure types including warehouses, buildings, storage tanks, equipment and machinery pads, highway embankments, retaining walls, earthen fills, berms, dikes, and levees. When comparing ground improvement to piling, it is important to understand that ground improvement may lead to savings related to foundation design and total construction costs, especially when not only the piling, but the associated pile caps, grade beams and structural slabs can be eliminated. An increasingly important benefit of ground improvement is environmental sustainability - in many cases less con- crete and steel is used in the foundation system. Menard Group USA is a design-build ground improvement contrac- tor with offices across the USA, offering solutions for a wide range of soil conditions and structure types. For more information or to discuss an upcoming project, pls contact info@menardgroupusa.com or call (412) 620-6000. MARTIN G. TAUBE, P.E., P.G. is Vice President of Business Development for Menard Group USA and works out of the Pittsburgh, PA office. He has more than 30 years of experience in geotechnical engineering, construction, and ground improvement. SONIA SORABELLA SWIFT, P.E. is Menard Group USA’s Design Manager and is based in Boston, MA. A registered Professional Engineer in eight states, she has more than 14 years of experience in ground improvement design and is responsible for the overall management of Menard’s design team and design protocols.
General range of applicable soil types for various ground improvement techniques
Where liquefaction is a potential risk, larger diameter drains know as Earthquake Drains can be installed. These drains are designed to alle- viate pore pressure build up during seismic events such as earthquakes, and reduce both the likelihood of liquefaction occurring and the amount of liquefaction-induced settlement that occurs. The drains are typically comprised of a 4-in-diameter slotted, flexible, corrugated pipe encased in a geotextile fabric. The drains are driven into the ground at spacings that typically range from 5 to 10 ft. Vibro Stone Columns/Aggregate Piers Vibro stone columns are continuous vertical columns of compacted aggregate that are formed using a vibratory probe to create vertical in- clusions with high stiffness and shear strength and improved drainage. Vibro stone columns typically range in diameter between 18 and 42 inches. When a vibratory probe is used to form the hole in which the stone column is constructed, then the elements are referred to as stone columns or vibratory stone columns. If separate drilling equipment is used to create the hole in which the stone is placed, then the elements are commonly referred to as aggregate piers. Stone columns are commonly used to reduce settlement and increase bearing capacity of soils for the support of structures. Because of their high shear strength, they are also commonly used to enhance slope stability and prevent lateral spreading. Stone columns can efficiently mitigate liquefaction resulting from the significant densification of granular layers that occurs during installation; enhanced drainage capacity is also a benefit for liquefaction mitigation. In spite of the versatility of stone columns, slower installation rates and subsequent higher cost of stone columns deeper than about 40 feet make their use for deeper soils less viable. Stone columns are also not applicable for very soft clays or organic soils where the columns would be prone to bulging which would lead to excessive settlement or even failure. Rigid Inclusions Rigid Inclusions are grouted vertical elements that typically range in diameter from approximately 12 to 18 inches. Rigid Inclusions are well adapted to high surface loading conditions and strict settlement requirements and are used to support slabs-on-grade, isolated footings, and embankments on compressible clays, fills and organic soils.
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