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Research Spending & Results

Award Detail

Doing Business As Name:University of Tennessee Knoxville
  • Khalid Alshibli
  • (865) 974-7728
Award Date:07/10/2020
Estimated Total Award Amount: $ 328,784
Funds Obligated to Date: $ 328,784
  • FY 2020=$328,784
Start Date:07/15/2020
End Date:06/30/2023
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.041
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:3D Dynamic Evolution of Pore Water-Air Interaction Within Saturated Sheared Sand
Federal Award ID Number:2016392
DUNS ID:003387891
Parent DUNS ID:003387891
Program:ECI-Engineering for Civil Infr
Program Officer:
  • Caglar Oskay
  • (703) 292-7774

Awardee Location

Street:1331 CIR PARK DR
Awardee Cong. District:02

Primary Place of Performance

Organization Name:University of Tennessee Knoxville
Street:1 Circle Park
Cong. District:02

Abstract at Time of Award

Many foundation systems are supported by water-saturated sand deposits. At the micro-scale, the voids between sand grains (pore space) are filled with water. The sand resists applied foundation loads through friction and interlocking between particles which is known as the shear strength of sand. The presence of air within the pore space in addition to water introduces new forces and fundamentally changes the shear strength of sand. The PI’s preliminary experiments show that standard procedures to saturate laboratory sand specimens may suffer from a major shortcoming despite decades of use and wide acceptance by the geotechnical community. It is difficult to eliminate all air bubbles from sand pore space and the widely used assumption of a 100 percent saturated state for a sand specimen with no change in degree of saturation is not correct. If the degree of saturation of a sand specimen changes from fully saturated to partially saturated during loading, then current testing procedures yield inaccurate measurements of shear strength which has a major impact on interpreting experimental measurements. This award will use dynamic four-dimensional (three space dimensions and time) imaging to investigate the role of air on the failure behavior of sand. The findings of this research advances knowledge in measuring and interpreting shear strength of sand, which have broad impacts on geotechnical engineering research, design, and practice. This research will provide an enriching research experience for undergraduate civil engineering students with emphasis on minority/female students and engage high school students in research in order to spark their interest in the field of civil engineering. The goal of this research is to monitor the evolution of sand-water-air interaction using fast dynamic synchrotron microcomputed tomography imaging at 6-micron resolution under shear loading conditions. This research will (i) investigate the influence of particle morphology and gradation on the degree of saturation of sheared sand; (ii) monitor local water-air interaction within pore space of sheared sand under drained condition; and (iii) evaluate the effects of specimen density on the change of degree of saturation of sheared sand. The following fundamental questions will be answered: (1) what is the minimum value of pore water pressure to maintain the same degree of saturation in sheared sand; (2) does the sand specimen remain 100 percent saturated when it is sheared; (3) if air bubbles develop; how they will evolve and what are the factors that affect their onset and growth. 3D probing of dynamic particle-water-air interaction is expected to offer unique measurements to support the development of a new particle-scale theory that better describes the behavior of saturated sheared granular materials. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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