Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

Evaluation, design, construction, and monitoring of foundations in karst geology are challenging tasks. The random presence of karst features, the variation in size, extent, and depth of karst features, and the different origin and geological characteristics of karst features make site characterization and investigation difficult. A balance between non-intrusive filed tests is useful to improve the site characterization. Non-intrusive field tests which provide multi-dimensional mapping such as Electrical Resistivity Imaging (ERI) or Ground Penetrating Radar (GPR) can provide spatial coverage instead of point data. Non-intrusive field tests which are not sensitive to moisture such as shear wave velocity measurements can better characterize the qualitative variations observed in ERI or GPR imaging. Intrusive field tests such as SPT and CPT can provide detailed characterization and quantitative measurements for design at targeted locations which are selected by pre-screening of non-intrusive test data rather than random choice of test locations. If the site characterization indicates the presence of karst features such as voids or raveling zones, alternative foundation options should be studied to see which option or combination of options can be suitable. Consequence of failure can be critical in determining the extents of the foundation deign for the presence of karst features and costs associated. Foundation elements should be designed to handle “manageable risk” scenarios. Possible loss of support and importance of redundancy should be taken into deign consideration and the random nature of loss of support can be taken into account as part of an assessment with and without a factor of safety evaluation. At least a case history (Countryside Christian Center) will be presented to demonstrate a foundation design in karst geology using intrusive and non-intrusive field measurements and with “manageable risk”. Evaluations resulted in recommending a shallow foundation / slab assuming possible loss of soil support in a limited area under the shallow foundation (slab) and also deep foundation elements taking into account possible loss of lateral support or loss of a limited number of piles. This paper encourages implementation of a smarter targeted field investigation rather than randomly punching holes in the ground and missing the voids and raveling zones. The extent and the level of the sophistication of foundation design are subject to the consequence of failure. Redundancy becomes important cost may by reduced by checking to see if the foundation can satisfy ultimate rather than service design condition when addressing the random loss of soil / rock support.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 4th, 12:00 AM

Composite Shallow & Deep Foundation in Karst Geology for the Countryside Christian Center New Sanctuary Clearwater, Florida

Chicago, Illinois

Evaluation, design, construction, and monitoring of foundations in karst geology are challenging tasks. The random presence of karst features, the variation in size, extent, and depth of karst features, and the different origin and geological characteristics of karst features make site characterization and investigation difficult. A balance between non-intrusive filed tests is useful to improve the site characterization. Non-intrusive field tests which provide multi-dimensional mapping such as Electrical Resistivity Imaging (ERI) or Ground Penetrating Radar (GPR) can provide spatial coverage instead of point data. Non-intrusive field tests which are not sensitive to moisture such as shear wave velocity measurements can better characterize the qualitative variations observed in ERI or GPR imaging. Intrusive field tests such as SPT and CPT can provide detailed characterization and quantitative measurements for design at targeted locations which are selected by pre-screening of non-intrusive test data rather than random choice of test locations. If the site characterization indicates the presence of karst features such as voids or raveling zones, alternative foundation options should be studied to see which option or combination of options can be suitable. Consequence of failure can be critical in determining the extents of the foundation deign for the presence of karst features and costs associated. Foundation elements should be designed to handle “manageable risk” scenarios. Possible loss of support and importance of redundancy should be taken into deign consideration and the random nature of loss of support can be taken into account as part of an assessment with and without a factor of safety evaluation. At least a case history (Countryside Christian Center) will be presented to demonstrate a foundation design in karst geology using intrusive and non-intrusive field measurements and with “manageable risk”. Evaluations resulted in recommending a shallow foundation / slab assuming possible loss of soil support in a limited area under the shallow foundation (slab) and also deep foundation elements taking into account possible loss of lateral support or loss of a limited number of piles. This paper encourages implementation of a smarter targeted field investigation rather than randomly punching holes in the ground and missing the voids and raveling zones. The extent and the level of the sophistication of foundation design are subject to the consequence of failure. Redundancy becomes important cost may by reduced by checking to see if the foundation can satisfy ultimate rather than service design condition when addressing the random loss of soil / rock support.