LARGE DIAMETER PILE LOAD TEST WITH A CASE STUDY USING OSTERBERG - CELL

Static loading test using single level bidirectional –Cell was tested in March 2017 at Paira bridge in Bangladesh for initial load testing. Soil consists of soft silt with traced clay from 0.0 m to 10.5 m underlain by various layer with very dense silty sand at the toe level and below. Pile was constructed reverse circulation method. Drilling slurry was composed of bentonite slury for 2.5 m diameter pile. The load cells were attached to a reinforcing cage at 18 m above toe. Static load test was 28days of casting the pile and tested. Testing was carried as per ASTM 1143 with load increment 7.5 % estimated ultimate load. It was observed that downward movement of reaching 220 mm and locked downward movement and O-Cell was given force for upward movement to find out skin fraction. Detailed analysis was carried out and it was found that ultimate load consisted of 49 MN skin frication and 30 MN end bearing sand safe design load was calculated as 33 MN.