Impact of Routine Quality Assurance on Reliability of Bored Piles

Quality assurance (QA) tests, such as integrity tests, are routinely conducted to ensure the safety of pile foundations. QA tests provide additional information and result in changes in estimated reliability of pile foundations. This paper aims to formalize a procedure to quantitatively evaluate the impact of routine QA tests on the reliability of pile foundations. Three cases of reliability analyses based on interface coring of large-diameter bored piles are studied; namely, no toe debris detected, toe debris detected without repair, and toe debris detected and repaired. The prior information of the occurrence probability and thickness of toe debris is established based on a practice survey and accumulated QA data. The Bayesian approach is then applied to update the occurrence probability and the mean toe debris thickness based on outcomes of on-site QA tests and remedial actions taken after these QA tests. Subsequently, the reliability of the piles can be updated. The updated reliability can be significantly higher than that before the QA tests. The degree of reliability improvement depends on the pile specifics, the outcomes from the QA tests, and the remedial actions taken after the QA tests.

[1]  Wilson H. Tang,et al.  Use of Load Tests for Reducing Pile Length , 2002 .

[2]  M C McVay,et al.  CALIBRATING RESISTANCE FACTORS IN THE LOAD AND RESISTANCE FACTOR DESIGN FOR FLORIDA FOUNDATIONS , 1998 .

[3]  S. Lacasse,et al.  UNCERTAINTY IN API PARAMETERS FOR PREDICTION OF AXIAL CAPACITY OF DRIVEN PILES IN SAND , 1989 .

[4]  Gregory B. Baecher,et al.  Factors of safety and pile load tests , 1982 .

[5]  Xxyyzz.  Fatigue Reliability: Quality Assurance and Maintainability , 1982 .

[6]  M. Shinozuka,et al.  Optimum structural design based on reliability and proof-load test. , 1969 .

[7]  Achintya Haldar,et al.  Fatigue‐Reliability Updating through Inspections of Steel Bridges , 1994 .

[8]  J. M. Amir,et al.  DESIGN OF SOCKETED DRILLED SHAFTS IN LIMESTONE , 1994 .

[9]  Bruce R. Ellingwood,et al.  Role of non-destructive evaluation in time-dependent reliability analysis , 1998 .

[10]  Howard Raiffa,et al.  Applied Statistical Decision Theory. , 1961 .

[11]  M W O'Neill,et al.  STRUCTURAL RESISTANCE FACTORS FOR DRILLED SHAFTS CONSIDERING CONSTRUCTION FLAWS. IN: CURRENT PRACTICES AND FUTURE TRENDS IN DEEP FOUNDATIONS , 2004 .

[12]  L C Reese,et al.  DRILLED SHAFTS: CONSTRUCTION PROCEDURES AND DESIGN METHODS , 1999 .

[13]  Wilson H. Tang,et al.  Probability concepts in engineering planning and design , 1984 .

[14]  Li Min Zhang.  RELIABILITY VERIFICATION USING PROOF PILE LOAD TESTS , 2004 .

[15]  Li Min Zhang,et al.  LATERAL OR TORSIONAL FAILURE MODES IN VERTICALLY LOADED DEFECTIVE PILE GROUPS , 2004 .

[16]  James Neil Kay.  Safety Factor Evaluation for Single Piles in Sand , 1976 .

[17]  Torgeir Moan,et al.  Initial Crack Depth and POD Values Inferred From In-Service Observations of Cracks in North Sea Jackets , 2000 .