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Thursday, 18 April 2019 00:00

Dynamic Load Tester for High Strain Dynamic Testing of Drilled Pile Foundations

The PDA-DLT software allows for real-time assessment of Force vs. Displacement as well as a cumulative summary table The PDA-DLT software allows for real-time assessment of Force vs. Displacement as well as a cumulative summary table.

Dynamic testing was initially developed to determine the static resistance of a driven pile during installation and has also been used as a reliable means to test drilled and bored foundations for over 40 years. Last year, Pile Dynamics, Inc. released the Pile Dynamics Analyzer – Dynamic Load Tester (PDA-DLT) system and associated software, which is specifically designed for high strain dynamic testing of drilled pile foundations.

The Pile Dynamics Analyzer – Dynamic Load Tester was designed specifically for quality assurance testing of drilled shafts and bored piles. The system acquires data from accelerometers and strain transducers attached to a pile or shaft so that High Strain Dynamic Tests (ASTM D4945) may be performed. The PDA-DLT allows for multiple configurations of force measurement (such as a force transducer) while evaluating bearing capacity, structural integrity, foundation stresses, and tabulates data over the few blows applied to a drilled foundation.

Tom Hyatt, P.E., of the GRL Engineers' Georgia office, recently used the Dynamic Load Test (DLT) system for a contracted APPLE Load Testing project. The project required that the seven production Augered Cast-In-Place (ACIP) piles be dynamically proof load tested to a minimum geotechnical resistance of 200 tons (400 kips), without overstressing or incurring excessive permanent settlement of the foundations. The foundations were tested by applying two to three drops, ranging in heights from six inches (152mm) to 1.5 feet (457mm).

The new features in the PDA-DLT system and software allowed the engineer to easily input the required information for the load cell that was used for testing, as well as the pile property information. After each impact, the permanent set was measured and input directly into the PDA-DLT software. Following the testing's conclusion, the engineer could quickly determine the cumulative set for all of the impacts. Additionally, the PDA-DLT software generates a Force vs. Displacement curve which allowed the engineer to use engineering judgment and determine whether additional impacts were required or if the desired load had been reached.

The PDA-DLT allows for up to 16 channels of data acquisition with eight WiFi boxes, and any combination of strains and accelerometers. The PDA-DLT software can model the changes in materials and be used to calculate pile stresses. All PDA-DLT channels, either in WiFi, Wireless or Traditional modes, are compatible with Smart Sensors (no need to input sensor calibration into the PDA).

This is part of the latest Newsletter of Pile Dynamics, Inc: No. 90_Use of the PDA-DLT Software on Drilled Shaft Foundations

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