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Friday, 19 May 2017 13:50

Static and Dynamic Load Testing of Large Diameter Pipe Piles

The Ohio Department of Transportation (ODOT) concurrently had funded a research project on large diameter pipe piles with Case Western Reserve University (CWRU), for which GRL had agreed to provide in-kind support. GRL, CWRU, and ODOT developed an instrumentation plan to satisfy the needs of both projects by collecting measurements during pile driving and during static load testing.

 The design and application of Large Diameter Open End Pipe Piles (LDOEPPs) is of significant interest to designers. Larger foundation elements are commonly chosen to provide solutions to a variety of design challenges including vessel collision, seismic events, liquefaction, or scour. For construction of the SR 36 bridge over the Tuscarawas River in Gnadenhutten, Ohio, 48” diameter, open end, pipe piles with interior constrictor plates were chosen for the foundation type. EPA regulations restricted the amount of concrete that could be placed in the river, and therefore, a traditional cofferdam and pile cap was not an option. A static load test (designed up to 2,200 kips) was also specified to evaluate the API design methods used by the designer.

The Ohio Department of Transportation (ODOT) concurrently had funded a research project on large diameter pipe piles with Case Western Reserve University (CWRU), for which GRL had agreed to provide in-kind support. GRL, CWRU, and ODOT developed an instrumentation plan to satisfy the needs of both projects by collecting measurements during pile driving and during static load testing. The instrumentation program included 16 vibrating wire strain gages, 28 resistive strain gages, and 10 accelerometers at various locations along the pile. With help from the contractor, Complete General Construction Company, GRL and graduate students from CWRU spent 5 days instrumenting the load test pile. The results of the dynamic pile testing during production pile driving will also be included in the research study.

The static load test pile was just 50 feet in total length, but was instrumented at six elevations and included over 2,000 feet of instrumentation wire and 250 feet of steel angle for wire and gage protection. The constrictor plate was located 20 feet above the pile tip and was a reinforced flat steel plate with a 23” opening in the center to allow soft soils to pass and alleviate trapping water during driving. The pile was driven with an APE D100-42 diesel hammer to 40 feet embedment into dense sand and gravel. Dynamic data was collected with three Pile Driving Analyzers® during driving, each collecting up to 14 individual channels of data through wireless connection. At the end of initial driving, data analysis using CAPWAP® software indicated the soil resistance was well below the required ultimate bearing capacity. Restrike testing two weeks later indicated a 40% increase in soil resistance. For comparison, dynamic monitoring was also performed on one reaction pile which did not have an interior constrictor plate. These results indicated that the reaction pile without the constrictor plate had 60% less compression capacity at the end of driving and during restrike than the pile with the constrictor plate. This demonstrated the effectiveness of the interior constrictor plate to increase the soil resistance by forcing a soil plug.

You can read the whole article in the latest newsletter of Pile Dynamics

Source: Pile Dynamics

Read 551 times Last modified on Friday, 19 May 2017 14:18

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