Upscaled Modeling of MICP for Field Deployment

Upscaled Modeling of MICP for Field Deployment

Researcher: Maya El Kortbawi (PhD, 2021)

Abstract:

Substantial research has been completed on cemented sands over the past few decades to address fundamental gaps in our understanding of cementation in natural deposits and to accelerate developments in cementitious ground improvement technologies such as the recently emerged bio-cementation techniques and specifically microbially-induced calcite precipitation (MICP).  However, the adoption of these techniques in the field is still limited due to the lack of a constitutive model capturing the change in behavior. Therefore, this study aims to develop a constitutive model which mathematically describes the behavior of cemented sands subject to earthquake loading and thus advises the design of the bio-cementation techniques as tools for hazard mitigation. The baseline model is PM4Sand v. 3.1 (Boulanger and Ziotopoulou 2017).

This project started with a timely collection of recent experimental and numerical studies on naturally and artificially cemented sands in order to provide new insights and contribute towards building a comprehensive dataset that would extend research impacts beyond individual studies. This extensive literature review has confirmed that the available body of experimental data for cemented sands is limited. This is mainly due to challenges associated with material sampling and characterization. As the experimental database is currently being enriched, experimental results will provide insights into the development and recasting of constitutive equations of PM4Sand. The new constitutive model will be validated on the element and system levels.

 

Comparison between simulations and experiments for untreated and treated MICP specimen
             Figure 1: Comparison of DSS monotonic response between original PM4Sand simulations and experiments for untreated and treated samples: (a) stress-strain responses, and (b) stress paths.
Comparison between simulations and experiments for treated samples cyclically loaded
           Figure 2: Comparison of DSS cyclic response between original PM4Sand simulations and experiments for treated samples cyclically loaded (CSR = 0.3): (a) stress-strain responses, and (b) stress paths.

References:

  1. DeJong, J. T., Ziotopoulou, K., Gomez, M. G., El Kortbawi, M., San Pablo, A.[et al.] (2021). Biocementation Ground Improvement for Liquefaction Hazard Mitigation. Invited Keynote. 20th International Conference on Soil Mechanics and Geotechnical Engineering (ICSMGE). Sydney, Australia. Abstract submitted.
  2. El Kortbawi, M., Ziotopoulou, K., Gomez, M. G., & Lee, M. (2020). Mechanical behaviour of artificially cemented sands: experimental and numerical developments. Géotechnique (under review).
  3. Lee, M., El Kortbawi, M., Gomez, M. G., and Ziotopoulou, K. (2020). Examining the liquefaction resistance of cemented sands using Microbially-Induced Calcite Precipitation and Gypsum. ASCE GeoCongress, Minneapolis.
  4. El Kortbawi, M., and Ziotopoulou, K. (2019). “Constitutive Modeling of the Cyclic Response of (Bio-) Cemented Sands.” Proc. 7th International Conference on Earthquake Geotechnical Engineering (ICEGE), Rome, Italy.
  5. El Kortbawi, M., Ziotopoulou, K., Gomez, M. G., and Lee, M. (2019). Validation of a bounding surface plasticity model against the experimental response of (bio-) cemented sands. GeoCongress, Philadelphia, PA.