external damage is shown. The standard deviation decreases from approxi- 

 mately 3 to 2.5 mV when the ultrasonic transducers are positioned closer 

 to the damage. When the transducers are placed directly over the damage, 

 the standard deviation decreases to approximately 1.7 mV. The ultrasonic 

 readings taken in quadrant 2 fluctuate slightly without regard to the 

 damage exhibited. 



RX POSITION 



(a) Pile 8, quadrant 1. 



D » 



' 4 

 D 

 E 3 



I 2 

 I' 



" 



„ r*"~~-: — -»— 



s 





H t 





12 3 4 3 6 



7 8 



9 1C 



RX POSITION 



(b) Pile 8, quadrant 2, 



Figure 17. Ultrasonic field tests: standard deviation (100 usee) 

 versus position of receiver (RX) for Pile No. 8. 



Figure 18 gives the standard deviation readings over 100 usee for 

 pile no. 5. Again, two quadrants were evaluated. The greatest amount 

 of damage in quadrant 2 (Figure 18a) is shown between line markings 3 

 to 5. As shown, the standard deviation is low at lines 3 and 5. Quad- 

 rant 3 (Figure 18b) has minimal damage with the greatest damage depth 

 being 0.6 inch. In the damaged region of quadrant 3, the standard devi- 

 ation fluctuates from approximately 0.2 to 0.6 mV. In comparison, the 

 standard deviation in the solid region ranges from 0.6 to 1.1 mV. 



The external damage shown on pile no. 1 is almost nonexistent 

 (Figure 19a). Yet, the standard deviation varies from approximately 1.8 

 to 20.1 mV. This fluctuation in the standard deviation is observed where 

 no change in the pile condition is shown. 



Figure 19b shows the change in the standard deviation with the 

 external damage over 100 usee for the Support Pile. The standard devi- 

 ation decreased from a range of approximately 0.7 to 1.8 mV in the solid 

 region to 0.4 to 0.5 mV in the damaged region. 



33 



