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Geomechanics and Engineering
  Volume 17, Number 5, April10 2019, pages 429-438
DOI: https://doi.org/10.12989/gae.2019.17.5.429
 


Debonding of microbially induced carbonate precipitation-stabilized sand by shearing and erosion
Jinung Do, Brina M. Montoya and Mohammed A. Gabr

 
Abstract
    Microbially induced carbonate precipitation (MICP) is an innovative soil improvement approach utilizing metabolic activity of microbes to hydrolyze urea. In this paper, the shear response and the erodibility of MICP-treated sand under axial compression and submerged impinging jet were evaluated at a low confining stress range. Loose, poorly graded silica sand was used in testing. Specimens were cemented at low confining stresses until target shear wave velocities were achieved. Results indicated that the erodibility parameters of cemented specimens showed an increase in the critical shear stress by up to three orders of magnitude, while the erodibility coefficient decreased by up to four orders of magnitude. Such a trend was observed to be dependent on the level of cementation. The treated sand showed dilative behavior while the untreated sands showed contractive behavior. The shear modulus as a function of strain level, based on monitored shear wave velocity, indicated mineral debonding may commence at 0.05% axial strain. The peak strength was enhanced in terms of emerging cohesion parameter based on utilizing the Mohr-Coulomb failure criteria.
 
Key Words
    microbially induced carbonate precipitation (MICP); bio-cementation; triaxial testing; impinging jet testing; erodibility
 
Address
Jinung Do, Brina M. Montoya and Mohammed A. Gabr: Department of Civil, Construction, and Environmental Engineering, North Carolina State University, 2501 Stinson Drive, Raleigh, NC 27607, U.S.A.
 

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