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A platform for research: civil engineering, architecture and urbanism
Capacity Analysis of Drilled Shafts with Defects
This paper presents the results of a study to quantify the effect of defects on drilled shafts under axial loading. These results represent the efforts of the first phase of a multi-phase project with the goal of delivering a validated computation tool that will permit the direct assessment of the load carrying capacity and performance of drilled shafts that have been rejected due to the detection of defects by non-destructive evaluation (NDE) methods. Current and historical industry practices for considering defects have been investigated and commonly occurring defects have been characterized in terms of shape, size, and location. A two-dimensional model for assessing drilled shaft behavior has been developed using the commercial finite element program PLAXIS and verified by reproducing existing axial load test data of "near perfect" drilled shafts. The validated model was then used to analyze weak layer and neck-in type defects in three cohesive soil profiles. A parametric study of the size, strength, and position of the defects was been performed and their effect on the load carrying capacity of an idealized shaft is presented. The results of this analysis show that under axial loading, the effect of a defect is highly dependent upon the geotechnical capacity of a drilled shaft. A shaft in stronger soil will experience greater loads and will therefore be more affected by presence of a defect than a shaft in weaker soil. The position of a defect is also critical in determining its effect on shaft capacity Under axial loading, the top of the shaft is the critical location. Defects located at the midpoint and toe of the shaft were found to have a greatly reduced effect on shaft capacity compared to those located at the top of the shaft.
Capacity Analysis of Drilled Shafts with Defects
This paper presents the results of a study to quantify the effect of defects on drilled shafts under axial loading. These results represent the efforts of the first phase of a multi-phase project with the goal of delivering a validated computation tool that will permit the direct assessment of the load carrying capacity and performance of drilled shafts that have been rejected due to the detection of defects by non-destructive evaluation (NDE) methods. Current and historical industry practices for considering defects have been investigated and commonly occurring defects have been characterized in terms of shape, size, and location. A two-dimensional model for assessing drilled shaft behavior has been developed using the commercial finite element program PLAXIS and verified by reproducing existing axial load test data of "near perfect" drilled shafts. The validated model was then used to analyze weak layer and neck-in type defects in three cohesive soil profiles. A parametric study of the size, strength, and position of the defects was been performed and their effect on the load carrying capacity of an idealized shaft is presented. The results of this analysis show that under axial loading, the effect of a defect is highly dependent upon the geotechnical capacity of a drilled shaft. A shaft in stronger soil will experience greater loads and will therefore be more affected by presence of a defect than a shaft in weaker soil. The position of a defect is also critical in determining its effect on shaft capacity Under axial loading, the top of the shaft is the critical location. Defects located at the midpoint and toe of the shaft were found to have a greatly reduced effect on shaft capacity compared to those located at the top of the shaft.
Capacity Analysis of Drilled Shafts with Defects
Petek, Kathryn (author) / Felice, Conrad W. (author) / Holtz, R. D. (author)
International Deep Foundations Congress 2002 ; 2002 ; Orlando, Florida, United States
Deep Foundations 2002 ; 1120-1135
2002-02-01
Conference paper
Electronic Resource
English
Capacity Analysis of Drilled Shafts with Defects
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