Understanding How Earthquakes Affect the Built Environment: Day 5
This engineering educational module on the behavior of piles in soft clays during earthquake loading seeks to introduce engineering as a viable career to 5th-8th graders and teach students how geotechnical engineers design foundations in marginal soils to minimize damage to infrastructure during earthquakes. A five-hour module is presented to simulate real-world behavior of piles in soft clays during earthquake loading and visually show the improvement in how these same piles behave after being stabilized with a deep soil mixing technique. In this module, soft soil is simulated by using Jell-O®, piles are simulated using Slim Jims® and soil stabilization is simulated using peanut butter, marshmallows or cheese. Each student group has to design a stabilization procedure to strengthen the piles. The students compete to see who can design a pile with the least amount of deflection for the least amount of money. This five-hour module is divided into hour long segments for ease of application.
Pile foundations are an integral part of many civil engineering structures, such as highway bridges, port facilities and tall buildings. Foundations can have a huge impact on an above ground structures' ability to withstand earthquakes. If a foundation is built strong enough, the damage to the above ground structure will be minimal. Therefore, it is important to understand how to build foundations in areas of the world where the soil is not very strong. In some cases, it becomes necessary to improve the soil using material like cement. The interaction between the foundation and the soil is called "Soil-structure interaction" and it is very important in geotechnical engineering, but is difficult to "see" because it happens underground. In order for students to fully grasp how a pile foundation in soft soil would be affected by an earthquake and how it would behave after the surrounding soil was improved, it is imperative to use simulated soil allowing students to "see" into the subsurface to observe pile behavior underneath the ground during an earthquake. Jell-O® is used as "soft clay" soil because it is translucent, as well as soft enough to show adequate deflections in an unimproved pile. Slim Jims® (beef jerky) are the pile material, creamy and crunchy peanut butter, small and large marshmallows, as well as sharp cheddar cheese are the stabilizing material to improve the pile performance, and Lollipops are inserted into the top of the Slim Jim® piles to simulate a structure. The students compete to see who can design a pile with the least amount of deflection for the least amount of money using a predetermined cost list and an optimization equation. This module can be administered to a class size as small as 5 to as large as 35 (or more) with enough help. The larger the class, the more Jell-O® has to be made. The average 2011 cost per group, including all supplies and after a shaker has been built, is roughly $10, although this cost can be offset by having each student bring in a plastic tub, a box of Jell-O® and some excavating spoons.
Earthquake Engineering Component
The goal of this activity is to teach students about geotechnical engineering and strengthening foundations to lessen movements and therefore, damages, due to earthquakes. The model is a direct comparison to real-life examples of improving the behavior of bridges built in soft soil by using cement deep soil mixing to strengthen the existing pile foundations. In this case, the cement deep soil mixing is simulated using a variety of edible materials with different cohesive and strength properties, such as cheese, peanut butter and marshmallows. This model is relevant to the field of earthquake engineering because every year, thousands of people lose their lives due to structure collapses during and after earthquakes. Many of these collapses could be prevented by building better foundation systems.
Learning Objectives and Standards
Links to the National Science Standards and to individual State Science Standards are available by using this link:
The specific learning outcomes of this module are to: 1. Learn the importance of geotechnical engineering and foundation systems in keeping structures safe during earthquakes. 2. Improve a zone of soft soil around piles to reduce movement, therefore, minimizing earthquake induced damage. 3. Gain insight into geotechnical engineering to broaden career path opportunities. 4. Improve the perceptions of engineers and the engineering profession.
The standards pertaining to Day 5 of this module are as follows:
OAC 210:15-3-78: Standards for Inquiry, Physical, Life, and Earth/Space Science
Process Standard 3.1. Ask questions about the world and design investigations that lead to scientific inquiry. Identify testable questions based on prior knowledge, background research, or observations.
Process Standard 4.3. Evaluate data to develop reasonable explanation, and/or predictions.
Process Standard 4.4. Determine if results of investigations support or do not support hypotheses.
Process Standard 4.5. Communicate scientific processes, procedures, and conclusions (e.g., model, poster, diagram, journal entry, lab report, scientific paper, oral presentation, and digital presentation).
Process Standard 5.1. Ask questions that can be answered through scientific investigation.
Process Standard 5.3. Use the engineering design process to address a problem or need (e.g., identify a need, conduct background research, prepare preliminary designs, build and test a prototype, test and revise design, communicate results).
Process Standard 5.5. Develop a logical relationship between evidence and explanation to form and communicate a valid conclusion, and suggest alternative explanation.
OAC 210:15-3-46.1: MATHEMATICS: Grades 6 - 8
Process Standard 2.2. Reflect on and justify reasoning in mathematical problem solving (e.g., convince, demonstrate, formulate).
Process Standard 3.1. Identify and extend patterns and use experiences and observations to make suppositions.
Process Standard 3.2. Use counter examples to disprove suppositions (e.g., all squares are rectangles, but are all rectangles squares?).
Process Standard 4.1. Apply mathematical strategies to solve problems that arise from other disciplines and the real world.
Day 5 Module
- Teacher created powerpoint or slides discussing earthquakes and their damages to infrastructure, the relationship between the experiment and the real-world, and student results and observations
Day five of the classroom visits (Duration: 50 min - 1 class period) a. Concept development -- relate the model and the students' designs to the research; b. Learn about geotechnical engineering, foundation engineering, piles and pile groups, earthquake engineering, soil-structure interaction, and ground improvement. c. Followed by questions and answers
Links and Resources
A full report on this module is given here: Cerato, A.B., Taghavi, A., Muraleetharan, K.K. and Miller, G.A. (2011). Understanding and Improving the Seismic Behavior of Pile Foundations in Soft Clays: An Educational Module. Report submitted to NEES-Comm, 80 pp. (https://nees.org/resources/2705)
Jell-O® Activity Day 5:
1. Describe the engineering design process. How did your design process for this experiment work?
2. Describe what geotechnical engineers do, in general.
3. If you were the engineer who was going to build a bridge or a building in a seismically active area, what is some information about the area that you would need to know?
This module is based on real life examples. Every structure built on this earth has some sort of foundation system, anchoring that structure to the ground. Buildings without adequate foundations in seismically active areas do not fare well. However all the public sees is the damage to the above ground structure, and thinks that if the above ground structure is made stronger it will fare better during earthquakes. While partially true, if the foundation system is not strong, no matter how strong the structure is built, it will always fail. The foundation system strength and flexibility is one of the major keys to building earthquake resistant structures, and introducing the concept of geotechnical engineering into middle schools can help to educate our future workforce.
This module could also be used at various educational levels, from elementary to high school, as well as at the undergraduate level, with appropriate modifications. For example, in elementary school, the Jell-O® play (Day 3) and Jell-O® design (Day 4) could be the highlights of the module, whereas, in high school, the science behind soil stabilization could be stressed more, while still allowing the students to play with the Jell-O® and stabilization procedures.
Researchers should cite this work as follows: