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The Effect of Microbial-Induced Carbonate Precipitation (MICP) on Sand : = Dynamic Properties and Seismic Site Response.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	The Effect of Microbial-Induced Carbonate Precipitation (MICP) on Sand :/
Reminder of title:	Dynamic Properties and Seismic Site Response.
Author:	Na, Kyunguk.
Description:	1 online resource (236 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Contained By:	Dissertations Abstracts International85-03B.
Subject:	Strain gauges. -
Online resource:	click for full text (PQDT)
ISBN:	9798380263276

The Effect of Microbial-Induced Carbonate Precipitation (MICP) on Sand : = Dynamic Properties and Seismic Site Response.
Na, Kyunguk.

The Effect of Microbial-Induced Carbonate Precipitation (MICP) on Sand :Dynamic Properties and Seismic Site Response. - 1 online resource (236 pages)

Source: Dissertations Abstracts International, Volume: 85-03, Section: B.

Thesis (Ph.D.)--North Carolina State University, 2023.

Includes bibliographical references

Microbial Induced Carbonate Precipitation (MICP) is a ground improvement technique that has gained significant attention in geotechnical engineering due to its potential for enhancing soil stiffness and mitigating liquefaction triggering. One of the crucial factors in predicting the seismic response of a given sedimentary column are the strain-dependent dynamic properties (shear modulus reduction and damping ratio curves) of the soils composing the column. Despite the growing interest in MICP, limited research has been conducted on its strain-dependent dynamic properties and their impact on geotechnical earthquake engineering applications. Advancing fundamental knowledge in this area is essential to support future large-scale implementation of this ground improvement technique.To address this knowledge gap, a comprehensive study was carried out, which began with the development of a Resonant Column (RC) test program suitable for MICP-treated specimens. The test program involved validity tests for MICP-treated specimens with the RC testing device incorporating a modified porous disk.The developed RC test program paved the way towards compiling an experimental database of MRD curves for MICP-treated poorly graded sands. To cover a wide range of strain levels that are relevant to seismic site responses for MICP-treated sites (10-4< ɣ < 1%), the study combined results from the RC and cyclic direct simple shear (cyclic-DSS) devices. The study involved conducting in-depth parametric studies by changing cementation levels and confining pressures for two different poorly graded sands. Through the systematic investigation of the relationship between cementation level and dynamic properties, the study revealed that the degree of cementation had a significant impact on initial dynamic properties (initial shear modulus and damping ratio), nonlinearity of MRD curves, and shear strain-related thresholds (linear elastic and volumetric shear strain thresholds).Subsequently, a best-fitting prediction formulation for the MRD curve of MICP-treated sands was developed, incorporating the increase in shear wave velocity from MICP, Vs, as an indicator of cementation level. The proposed functional form provides a practical tool for engineers to evaluate the relationship between the MICP treatment and the resulting seismic performance of the improved soils.Finally, a fully nonlinear seismic site response analysis was conducted using the proposed MRD prediction curves for MICP-treated sands. The analyses performed using DEEPSOIL V.7 examined various factors affecting seismic performances, such as cementation level, location of cemented layers, distribution of equivalent mass of calcium carbonate, and uniformity in the cementation distribution. This study found that the aforementioned cementation design scenarios had varying effects on the characteristics of outcrop ground motions estimated, with some design scenarios significantly modifying the estimated outcrop ground motions (e.g., location of cemented layers) while others had only a minor effect (e.g., uniformity in the cementation distribution).In conclusion, this study provides insights into the dynamic behavior of MICP-treated sands and contributes to the optimized treatment design of bio-inspired ground improvement techniques for geotechnical earthquake engineering applications. The proposed MRD prediction curves for MICP-treated sands also serve as a valuable resource for geotechnical engineers and researchers, enabling more accurate assessments of the seismic site response of MICP-treated soils.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380263276Subjects--Topical Terms:

1465476
Strain gauges.
Index Terms--Genre/Form:

554714
Electronic books.

The Effect of Microbial-Induced Carbonate Precipitation (MICP) on Sand : = Dynamic Properties and Seismic Site Response.
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520 $a Microbial Induced Carbonate Precipitation (MICP) is a ground improvement technique that has gained significant attention in geotechnical engineering due to its potential for enhancing soil stiffness and mitigating liquefaction triggering. One of the crucial factors in predicting the seismic response of a given sedimentary column are the strain-dependent dynamic properties (shear modulus reduction and damping ratio curves) of the soils composing the column. Despite the growing interest in MICP, limited research has been conducted on its strain-dependent dynamic properties and their impact on geotechnical earthquake engineering applications. Advancing fundamental knowledge in this area is essential to support future large-scale implementation of this ground improvement technique.To address this knowledge gap, a comprehensive study was carried out, which began with the development of a Resonant Column (RC) test program suitable for MICP-treated specimens. The test program involved validity tests for MICP-treated specimens with the RC testing device incorporating a modified porous disk.The developed RC test program paved the way towards compiling an experimental database of MRD curves for MICP-treated poorly graded sands. To cover a wide range of strain levels that are relevant to seismic site responses for MICP-treated sites (10-4< ɣ < 1%), the study combined results from the RC and cyclic direct simple shear (cyclic-DSS) devices. The study involved conducting in-depth parametric studies by changing cementation levels and confining pressures for two different poorly graded sands. Through the systematic investigation of the relationship between cementation level and dynamic properties, the study revealed that the degree of cementation had a significant impact on initial dynamic properties (initial shear modulus and damping ratio), nonlinearity of MRD curves, and shear strain-related thresholds (linear elastic and volumetric shear strain thresholds).Subsequently, a best-fitting prediction formulation for the MRD curve of MICP-treated sands was developed, incorporating the increase in shear wave velocity from MICP, Vs, as an indicator of cementation level. The proposed functional form provides a practical tool for engineers to evaluate the relationship between the MICP treatment and the resulting seismic performance of the improved soils.Finally, a fully nonlinear seismic site response analysis was conducted using the proposed MRD prediction curves for MICP-treated sands. The analyses performed using DEEPSOIL V.7 examined various factors affecting seismic performances, such as cementation level, location of cemented layers, distribution of equivalent mass of calcium carbonate, and uniformity in the cementation distribution. This study found that the aforementioned cementation design scenarios had varying effects on the characteristics of outcrop ground motions estimated, with some design scenarios significantly modifying the estimated outcrop ground motions (e.g., location of cemented layers) while others had only a minor effect (e.g., uniformity in the cementation distribution).In conclusion, this study provides insights into the dynamic behavior of MICP-treated sands and contributes to the optimized treatment design of bio-inspired ground improvement techniques for geotechnical earthquake engineering applications. The proposed MRD prediction curves for MICP-treated sands also serve as a valuable resource for geotechnical engineers and researchers, enabling more accurate assessments of the seismic site response of MICP-treated soils.
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