Strain Gauge Instrumentation of Spliced Concrete Piles in Soft Alluvial Soils

Instrumentation of statically loaded test piles using internal strain gauges provides the opportunity to refine the understanding of load distribution within a test pile. This allows for more accurate extrapolation of test results to other pile lengths and a reduction in the required number of static load tests resulting in significant cost savings for test pile programs. This case study relates the experience of a test pile program for a proposed $1.5B wharf located along the Mississippi River near New Orleans, Louisiana. Proposed foundation piles include 36-in.2, precast concrete piles driven in as deep as 70 ft of water. To meet project budget, the test pile program was performed using landside equipment requiring test piles be installed as two sections including a mechanical splice. The project design team deemed strain gauges as necessary to verify capacity estimates for piles at multiple tip elevations and with consideration for significant end bearing capacity anticipated from a solid bearing stratum near el-150. To provide this ability, the project design team worked with the splice manufacturer, pile casting yard, and construction manager at risk to incorporate splicing of instrumentation between the two test pile sections.