GEOTECHNICAL EARTHQUAKE ENGINEERING

Earthquakes in Tempe? Not likely. But there is plenty of earthquake engineering research in the geotechnical group at ASU under the direction of Prof. Ed Kavazanjian. In fact, Professor Kavazanjian, co-author of the existing FHWA guidance document (Figure 1) on geotechnical earthquake engineering is co-Principal Investigator on a team lead by PB Inc. (formerly Parsons Brinckerhoff) that was recently selected by FHWA to develop two training courses on seismic design of bridges, one on foundation design and one on the superstructure. Under subcontract to PB, beginning in 2008, ASU will be responsible for writing several chapters of the foundation design resource document and for developing the syllabus and teaching materials for the foundation design training course.

Figure 1. FHWA Design Guidance on Geotechnical Earthquake Engineering	Figure 2. ASU Large Scale Cyclic Simple Shear Testing Device

Other geotechnical earthquake engineering research at ASU includes National Science Foundation-funded research on the mechanical properties of municipal solid waste (MSW) subject to seismic loading and microbiological methods for improving the physical properties of soil. The research on MSW properties, a collaborative project with geotechnical researchers at U.C. Berkeley and U. Texas Austin, is employing unique large-diameter testing equipment in the ASU Enamul Hoque Geotechnical Laboratory to subject MSW recovered from a landfill near San Francisco to earthquake-type loading. Recommendations developed by Prof. Kavazanjian and his co-workers are widely acknowledged to represent the state of the art for determining the properties of MSW needed to assess how landfills will respond when subject to strong ground shaking in earthquakes. This project has already led to a series of technical papers describing enhanced understanding of these properties.

Microbiological improvement of the physical properties of soil is an important new research thrust in geotechnical engineering at ASU, capitalizing on ASUs strength in environmental microbiology. In conjunction with Professors Bruce Rittmann and Morteza Abbaszadegan, the geotechnical group is exploring several different means by which microbiological processes can be used to improve the physical properties of soil over time frames of engineering interest. With respect to earthquake engineering, the primary application of these techniques is mitigation of the liquefaction potential of soil by inducing cementation in granular soils. Liquefaction is one of the major sources of damage in earthquakes (Figure 3). Cementation of sands is a process that occurs over geologic time in natural deposits. However, cementation has also been observed to occur over much shorter time frames, i.e. time frames of engineering interest, typically in situations with this is an adverse effect, e..g. clogging of water treatment plant filters and in granular drains for dams and landfills. If these processes can be controlled such that they can be induced in target locations, they could be used to stabilize loose soil deposits against liquefaction, one of the largest sources of damage from earthquake. Coastal and riverfront communities and facilities throughout the United States and around the world in a cost-effective and sustainable manner.

Figure 3. Building Damage due to Liquefaction in the 1964 Niigata Earthquake