OasisLMS

Abstract: Concerns regarding defects in cast-in-place deep foundations are amplified for piles constructed closely together as the geotechnical and structural capacity of the pile could be compromised. Defects such as pile necking (i.e. reduction in cross section diameter) can occur when drilling nearby an adjacent foundation element undergoing curing processes with increasing lateral earth pressures and disturbances experienced by the freshly poured foundation element. The final design of the Metropolitan Transit Authority (MTA) Jamaica Bus Depot Expansion Phase I included approximately one-thousand, 24 in (0.6 m) diameter continuous flight auger (CFA) piles. The project design criteria limited pile installation within 15 ft (4.6 m) of grouted piles to a waiting period of twenty-four hours. This project presented challenges relating to establishing project site-specific disturbance zone criteria for uncased CFA piles. The Design-Build team devised an innovative approach to propose nondestructive testing during installation to quantify site-specific disturbance zone criteria for adjacent foundation construction and prove an acceptable and more efficient construction sequence for approximately one-thousand production piles. Results from Thermal Integrity Profiling (TIP) and Sonic Echo (SE) tests completed at three different locations during the test program showed no detected effect on the pile integrity from adjacent drilling. The study successfully demonstrated a reduced drilling distance of 12 ft (3.7 m) adjacent to freshly grouted piles as acceptable, as well as a distance of 6 ft (1.8 m) adjacent to piles which had cured for approximately sixteen hours. The Design-Build team achieved a favorable outcome for an increased production schedule as a result of this innovative use of TIP testing, which served benefit to all stakeholders.

Mr. Saad Rehmatullah; Mr. ALFREDAS DAUGIALA

Annual Conference Proceedings