Testing Unknown Foundations

Sometimes it is important to be able to test a foundation after it has been constructed even if such testing had not been originally planned.  Such cases often occur for the re-use of existing foundations or for evaluating a foundation for a transmission line tower, wind turbine or cellular communications tower.

FTC utilizes a form of non-destructive testing (low strain dynamic testing) called sonic echo/impulse response (SE/IR).  This test involves the use of an instrumented hammer and special receivers (an accelerometer or geophone) mounted to the top or side of the drilled shaft or pile. 

Usually there is enough of the foundation exposed at the top of the structure (outside the bolt circle) to perform testing without the need to remove the overlying structure (such removal is typically not an option anyway).  By analyzing the reflected compression waves (echoes) returned from the shaft or pile as a result of the impact from a hand-held hammer, many important characteristics such as overall integrity and foundation length can be determined.