Past and current research efforts in the use of nondestructive testing to evaluate the integrity and capacity of drilled shafts containing defects are described. The results of a drilled shaft test program containing both controlled and uncontrolled defects (five shafts at a dense soil site and six shafts at a soft soil site) are presented. The test program was designed to demonstrate in a relative way the ability to find defects, the ability to quantify the location and magnitude of defects, and the correlation of defects with acceptance criteria. Planned defects were created by attaching soil-filledbags to the rebar cages. Uncontrolled defects were created by usingimproper drilling procedures, such as pulling the tremie pipe out of the concrete, using low slump concrete for portions of the shaft, and using improper slurry control procedures. All shafts contained four preplaced access tubes attached to the rebar cage and were tested using both sonic logging and gamma logging procedures as well as surface reflection techniques (sonic echo test and transient dynamic response test). The approximate costs and relative effectiveness of the different nondestructive techniques in finding and quantifying defects in the shafts are discussed. This paper appears in transportation research record no. 1331, Integrity testing of foundations 1991
Samenvatting