Title: Understanding and Improving the Seismic Behavior of Pile Foundations in Soft Clays (NEES-2010-0952)
Year Of Curation: 2014
Description: Pile foundations are an integral part of many civil engineering structures. The seismic behavior of pile foundations is a very complex problem with interactions between soils (solid skeleton, pore water, and pore air), piles, and superstructure. This complexity is further exacerbated when weak soils such as soft clays and liquefiable loose sands surround the pile foundation. The behavior of pile foundations in liquefiable sands has been studied extensively; however, similar investigations for soft clays or seismic response of piles in improved soils have been rarely performed. The current seismic design practice calls for avoiding inelastic behavior of pile foundations by restricting their lateral displacements because it is difficult to detect damage to foundations following an earthquake. Limiting the lateral displacement of a pile foundation is relatively easy to achieve in competent soils. In the case of weak soils, the current practice is to use an increased number of more ductile, larger diameter piles that are difficult to design and expensive to construct. An innovative, and perhaps more cost-effective, solution to this problem is to improve the soil surrounding the pile foundation. For structures undergoing seismic retrofit with existing pile foundations in weak soils, in certain instances, improving the soils may be the only option to improve the seismic behavior of the foundation. This technique is not widely used in seismic regions due to lack of fundamental understanding of the behavior of improved and unimproved soils and the interactions between them as well as with the piles during earthquakes. As a first step in a long term objective of understanding and improving the seismic behavior of pile foundations in all weak soils, the proposed research will focus on soft clays. Soft clays are quite prevalent in earthquake prone areas of the U.S., but have received little attention from the research community.
PIs & CoPIs: Kanthasamy Muraleetharan, Amy Cerato, Sri Sritharan, Steven Vukazich
Dates: October 01, 2008 - September 30, 2012
Organizations: Iowa State University, IA, United States,,San Jose State University, CA, United States,,University of Oklahoma, OK, United States
Facilities: University of California, Los Angeles, CA, United States,University of California, Davis, CA, United States
Sponsor: NSF - 0830328
Keywords: Pile Foundations, Soft clay, CDSM, Cement Deep Soil Mixing ,seismic, Cyclic lateral loading, ground improvement, Soil-Structure Interaction, Centrifuge testing, Full scale testing, numerical model
Publications: Juan Pinilla, Gerald Miller, "Centrifuge Investigation of Seismic Behavior of Pile Foundations in Soft Clays" ,Juan Pinilla, Gerald Miller, "Centrifuge Investigation of Seismic Behavior of Pile Foundations in Soft Clays", "Seismic Response of CDSM Improved Soft Clay Sites Supporting Single Piles"
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