Providing sustainable foundation systems that protect against multi-hazards
In the next thirty years, the U.S. will need to provide cost-effective infrastructure repair for expanding populations while simultaneously protecting the natural environment. The U.S. infrastructure problems have been well-documented in the American Society of Civil Engineers' (ASCE) 2013 Report Card for America's Infrastructure, which gives the U.S. an average grade of a D+ and estimates that renewal would cost $3.6 trillion by 2020. Dr. Amy Cerato is creating and testing resilient and sustainable foundation systems in her 1.5 acre experimental facility to mitigate human and economic losses, as well as social disruption caused by infrastructure failures due to natural hazards. Recent natural disasters and terrorist acts have added a new dimension: now infrastructure must not only be adequate, it must be robust, it must be resilient and it must minimize risk. The implementation of Dr. Cerato's research will reduce life loss and make our structures more resilient to multi-hazards so that we can recover and re-establish our lives in days or weeks, rather than months or years.
Dr. Amy Cerato, Rapp Foundation Presidential Professor of the University of Oklahoma's Civil Engineering and Environmental Science Department is designing, testing and implementing resilient and sustainable foundation systems that will anchor our nation's infrastructure and allow it to withstand a host of multi-hazards, including extreme wind events (hurricanes, tornadoes), earthquakes, landslides and expansive soils. Various soils react differently to the environment, and so the foundation of a bridge, building, or dam must be built specifically for its soil conditions to protect society and reduce damage to the structure during a hazardous event. In the expansive soil arena, Dr. Cerato is discovering new ways to mitigate the estimated annual $15 billion in damages caused by this natural hazard to single family and commercial buildings and roadways. Expansive unsaturated soils are found in every state and cover one-fourth of the United States. They undergo large amounts of heaving and shrinking due to seasonal moisture changes which leads to cracking and buckling of the infrastructure. Providing sturdy structures that can withstand the shifting soil also offers an underground "safehouse" for protection against tornadoes. For underdeveloped or developing countries with limited access to concrete, Dr. Cerato has designed steel helical piles that can be screwed into the ground using animal or human power to support 1-10 kilowatt wind turbines. Additionally, Dr. Cerato has written an algorithm that identifies target areas for landslides.
Dr. Cerato's research is directed at making America's infrastructure more sustainable by resolving a number of foundation-related issues:
Soft or expansive soils happen to be congregated in a region of the country that is also susceptible to above ground multi-hazards (tornadoes, hurricanes, earthquakes), which only heightens the potential damage should one of these disasters strike. For many large-scale projects though, it is impossible to take down the structure and correct the problem. Instead, Dr. Cerato is designing, testing, and implementing resilient and sustainable foundation systems. For example, in a recent project her team discovered that cement can be used to strengthen existing deep foundations under bridges in soft soils in seismic zones using cement. For expanding soil under roadways that swells and leads to cracks, bumps, and potholes, Dr. Cerato is adding a chemical stabilizer that strengthens the soil and prevents swelling. She has developed a method using existing X-ray Fluorescence (XRF) technology, that determines the precise amount of calcium oxide in soil, which is used by transportation officials for construction quality control and geotechnical forensic investigations.
Slope stability along transportation corridors is essential for road safety and the safety of the surrounding inhabitants. Dr. Cerato has helped develop and validate an algorithm that can predict when and where a landslide will occur, using input metrics such as rainfall data, soil type and topography. This algorithm is continually being updated with new data, but shows promise in pinpointing locations of possible landslides so that transportation officials can take the correct precautionary measures.
Concrete is the single most widely used material in the world, but in small villages in developing countries or even remote areas of the U.S., the material is often inaccessible. To combat this issue, Dr. Cerato began designing "green" foundations; foundations that do not leave a footprint once the infrastructure is removed. Small wind turbines, for pumping water or generating electricity, can utilize steel helical piles, instead of concrete, as foundation elements. These helical piles can be screwed into the ground using animal or human power. They are "green" because not only is the installation process more efficient than using concrete, but should the structure need to be moved, the piles can simply be un-spun and leave no footprint behind. In 2008, Dr. Cerato completed a research study on the long-term cyclic response of full-scale helical piles, which was the first of its kind. Today, she is working with the Deep Foundations Institute to test helical piles in more types of soils under seismic loading so that these "green" foundations can be more widely used in areas that suffer from earthquakes. These piles are a more flexible foundation, and therefore respond better to seismic activity, but have yet to be extensively tested. There is also hope to further develop and test these foundations for industrial-sized 10-20 megawatt turbines.
Dr. Cerato decided to pursue engineering after a high-school teacher recommended that she volunteer for a summer program through the Student Conservation Association (SCA) in Cumberland Gap National Historic Park in Kentucky. While there, work included re-vegetating overused trails and rebuilding wetland walkways and horse gates all while living in the backcountry... with no running water. The group had to design a way to get access to drinkable water, and so Dr. Cerato was tasked to design and construct a water distribution system. She managed to construct a gravity system that provided potable water for seven humans, which was efficient enough that everyone had enough water to drink and cook with, while not getting sick over that six weeks. Her SCA team leader told her that she would be a great engineer. Dr. Cerato didn't know at the time what an engineer was, or what they do, so during her senior year in high school, she researched the profession and and decided that she would study Civil Engineering in college.
Following her junior year soil mechanics class, Dr. Cerato knew that she wanted to specialize in geotechnical engineering. She attended graduate school and was amazed at how little attention people paid to their foundations. If a natural disaster were to strike, many buildings, bridges and levees could come crashing down as a result of being built on a weak or aging foundation. She felt a duty to help make our infrastructure safer; to give people sufficient time to get off a bridge during an earthquake or to provide a safe-room below ground that could not only house inhabitants during severe wind events, but also mitigate against swelling soils. Dr. Cerato's plan at the time was to stay in school only long enough to earn her Masters degree, and then enter industry. She decided after her second year in graduate school, though, that she wasn't versed enough in her field, and she wanted to pursue a Ph.D. degree, where she then specialized in foundation systems. Her research of course led to more questions, and when she became a faculty member she decided to continue to find answers to the many questions she was uncovering. In maintaining her initial interest to enter industry, she strives to have her applied research implemented for real-world issues.
Dr. Cerato is passionate about taking her complex research projects and translating the concepts for middle and high schoolers in fun, high-impact exercises. She wants children to know about engineering so that when it comes time to choose a career, engineering is an option for them. She understands the need to start young so that the pipeline of future engineers will remain full. During a presentation for 8th graders, Dr. Cerato turned the pile foundations in soft soil under earthquake loading problem into a module where Jello was the soil, the foundation pile was a Slim Jim, and the cement stabilizer that Dr. Cerato adds during her work was modeled using peanut butter, marshmallows or cheese. The students had to decide how big the zone would need to be, as well as which materials to use in order to dampen the pile deflection during a simulated earthquake. Each material was assigned a cost, and the students had to optimize cost as well as performance. This completely edible module excited the students about geotechnical engineering and was a great way to understand visually how strengthening an existing pile in soft soil is an effective way to protect our transportation corridors. It took something as simple as one person mentioning engineering to Dr. Cerato during a volunteer opportunity during her junior year in high school to ultimately direct her to the work she currently does. One person can make a difference in a young person's life and it is extremely important to Dr. Cerato to bring exciting engineering research concepts to children in a fun, memorable way.