The International Information Center for Geotechnical Engineers

Monday, 25 September 2017 11:33

The Benefits of Dynamic Pile Testing

Any structure is only as good as its foundation. For a deep foundation to perform satisfactorily, it must have adequate geotechnical capacity to support the applied load and lack structural defects.

If If the foundation fails, it must be remediated or the structure demolished and eventually replaced; either option is tremendously expensive. Therefore, it is desirable to employ construction control methods which demonstrate a deep foundation’s geotechnical capacity and structural integrity.

For driven piles, a static load test checks the capacity, but due to cost and time considerations the number of static tests is generally very limited. Conversely, a dynamic formula is inexpensive and quick, but also notoriously inaccurate. These considerations prompted research over 50 years ago that resulted in dynamic testing, which can be applied at a relatively modest cost to a significant number of piles at multiple site locations to improve site characterization. The Pile Driving Analyzer® (PDA) with subsequent CAPWAP® signal matching has become state-of-practice. Dynamic testing is also applied to cast-in-situ piles (drilled shafts, bored piles, CFA/augercast piles) by employing a drop weight of sufficient size.

For larger projects, dynamic testing programs can optimize the foundation. Test program data can be used to select the best pile type and size by determining the geotechnical capacity at various depths and quantifying capacity changes with time (usually gains due to set-up) by testing both at end of drive and on restrike days, or even weeks later. Production piles are driven to criteria (usually a blow count tied to hammer performance) matching the successful dynamic test pile installation. Periodic testing during a long production pile installation documents that the hammer is performing consistently. For smaller projects, dynamic testing of the first production piles is generally sufficient to provide essential construction control criteria for the project.

Read the whole article of the benefits here

Ths article is part of the latest Pile Dynamics Newsletter No. 85.

Source: Pile Dynamics

Read 904 times Last modified on Thursday, 18 April 2019 14:44

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