<title>Borehole NDT techniques for unknown subsurface bridge foundation testing</title>

Inclination correction of the parallel seismic test for pile length detection

“…The parallel seismic (PS) test has been used to investigate the integrity and depths of unknown foundations under existing structures [11,15]. In order to perform the PS test, a borehole close to the tested foundation is drilled in the soil and filled with water to provide good acoustic coupling [3].…”

“…However, it is difficult to use the SE/IR method on existing foundations with an inaccessible head condition. The parallel seismic (PS) test has been shown to have potential for the detection of unknown depth foundations with an inaccessible head condition [6,8,11]. However, the interpretation of PS test results has assumed that the borehole in the site is perfectly parallel to the piles, which might not always be true in the site.…”

“…If the length of the foundations is not known accurately, necessary repair work might not be carried out in a timely fashion, and a major disaster may occur. Unfortunately, the design plans of old structures might be lost over time, and thus information about the foundation depth, geometry, or material quality would be unavailable [11]. Consequently, use of effective and fast methods to inspect the geometry of existing foundations is an important issue.…”

PS wave based parallel seismic test for pile length assessment

“…The parallel seismic (PS) test has been used for years to assess the integrity and the depth of existing piles (Olson et al, 1996;Kenai and Bahar, 2003;Herlein and Walton, 2007;Sack and Olson, 2009;Yu et al, 2010) and piles under construction (Wu and Yang, 2009;Huang and Ni, 2012). Compared to other non-destructive evaluation methods, this method is particularly useful in situations where the pile length is unknown or the pile head is not accessible for loading.…”

Experimental Study of Nondestructive Geophysical Methods for Evaluating the Condition of Concrete Structures

“…The National Construction Industry Research Centre (CEBTP) of France pioneered this technique in the mid-1970s (Lo et al, 2009). The test procedure is described in detail by many authors (i.e., Olson (2003); Olson et al, 1996). The test…”