American Society of Civil Engineers

Application & Interpretation of CSL Testing: Common Errors

by Bernard Hertlein, (Principal Scientist, STS Consultants, Ltd., 750 corporate Woods Parkway, Vernon Hills, Illinois 60061 E-mail:
Section: CSL and Drilled Shafts, pp. 1-11, (doi:

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Document type: Conference Proceeding Paper
Part of: Contemporary Issues In Deep Foundations
Abstract: While seeming simple in principle, thanks to the graphic nature of the output data, the Crosshole Sonic Log method is quite controversial as a quality control method for drilled shaft foundations. In the author’s opinion, this is largely due to the inexperience of both the operators, and the analysts. The test is deceptively simple to perform, and the data is relatively easy to understand. Determination of the nature of an anomaly, however, requires an understanding of the test method, the construction method, and an ability to perform a forensic analysis of the documented construction process. Determining the significance of the anomaly requires an understanding of the foundation design, the geotechnical properties of the soil in which it has been constructed, and the physical conditions under which it will support a structure. Not many people embody all these skills, so, usually, several people will be involved in the acceptance or rejection of a deep foundation. It is important that all of the people on this team have faith in the expertise of their fellow players. This paper looks at some of the common errors that have been identified in the last few years, primarily as a result of lack of expertise on the part of one or more people on the test and evaluation team.

ASCE Subject Headings:
Data analysis
Drilled shafts