Crosshole Sonic Logging (CSL) as Applied to Deep Foundations,” should be available this year through DFI. Ultimately, deep foundations are used to limit the displacement of the structures they support to a tolerable level. The engineer-of-record should be mindful of this when evaluating test results and should consider the impact any identified deficiencies or anomalies will realistically have on the actual performance of the foundation element. Instrumented load tests are invaluable tools to evaluate not only capacity but also constructability, quality and integrity. Load tests often show that less-than-perfect foundations will meet performance requirements. When the rejection of a drilled shaft occurs because of the QA data, implying the shaft will not accomplish its primary function, the authors argue that a direct measurement of that function, namely a load test, is highly beneficial. Several examples of drilled shaft QA methods and how observation or load testing can feed back into a proper analysis are presented below. Sidewall QA Currently, there are no commonly used in- situ methods to assess filter cake or sidewall integrity of a drilled shaft excavation. Therefore, assessing the quality of the bond between the excavation sidewall and placed concrete requires constructing a shaft and performing a load test. If numerous load tests are performed on a given site, in similar geotechnical conditions, variations in the capacity results may be due to variations in slurry or tooling. However, quantifying the condition of the excavation sidewall is a topic where additional research and technology is needed. At times, it is clear from field observations and drilled shaft installation logs that a given shaft may not perform as expected and load testing tends to support such correlations. Direct measurement of sidewall integrity and filter cake during construction would vastly improve the correlation between quality of the sidewall-concrete bond. Verticality and roughness can be assessed, wi th varying degrees of effectiveness, using commercially available 86 • DEEP FOUNDATIONS • MAY/JUNE 2019 mechanical or ultrasonic calipers. Verticality requirements mandated in standards and specifications often do not account for shaft diameter, encroachment or other factors that affect the structural per formance of an out -of -plumb foundation element. While it is certainly important to enforce a maximum allowable deviation from vertical, a rational justification should be made when forcing a contractor to re-drill a shaft for no practical benefit. ASTM D8232 (2018), Standard Test Procedures for Measuring the Inclination of Deep Foundations, was recently adopted to address the technology and its uses but further work is warranted. First, almost no specifications have referenced it because the standard is so new. Second, the International Building Code (IBC) and many local codes may supersede the ASTM standards, even if the ASTM standards are known. Local codes are often the most rigorous and inflexible. Decision-makers with knowledge are often powerless to make a proper value decision. Further discussion on this topic can be found in the Assessment of Bored Pile Verticality Using an Shaft inspection devices (SIDs) can aid engineers as they try to verify tip conditions. cased and dry. Experience suggests that full-length casings and dewatering schemes can drastically reduce the unit side resistance of a drilled shaft. Therefore, if downhole inspection is required, the engineer often must reduce or neglect skin friction. Ironically, this well-intended downhole QA procedure could actually result in a more expensive shaft, by disregarding potential side resistance and designing exclusively for end bearing. Although seeing and touching the shaft Slurry can affect side walls in unmeasurable ways and is impossible to see through. Ultrasonic Caliper by Sinnreich et al published in the proceedings from the 2018 International Foundation Congress and Equipment Expo (IFCEE). Shaft Base QA Historically, the bases of dry shaft excavations were evaluated by lowering an inspector down the hole. While uncom- mon today, when downhole inspection is performed, the excavation must be fully base may seem effective, it is still subjective. If there isn’t feedback from load testing and creation of a database, the observational method doesn’t provide value for future construction. LoadTest Consulting (LTC) conducted a bi-directional load test on a recent project in Atlanta, Ga. The 6 ft (1.8 m) diameter shaft was socketed approximately 20 ft (6.1 m) into what is locally characterized as partially weathered rock (PWR). The test
