High strain and low strain dynamic pile testing at the new blanchetown bridge, SA

This paper describes the use of dynamic pile testing during the construction of a new bridge over the Murray River at Blanchetown, SA. The bridge carries the Sturt Highway, which is the main road link between Adelaide and Sydney. The bridge foundations comprise groups of driven precast prestressed concrete piles and dynamic pile testing was used to establish driving criteria and to confirm pile resistance. At Pier 1, on the Adelaide side of the river, the first piles did not stop at the expected founding level and dynamic testing was used to investigate their behaviour. The testing indicated all piles were broken. A program of high strain and low strain dynamic testing was then used to assess the piles and to investigate alternative methods for successfully driving piles at the required locations. The paper describes the testing methods and an interpretation of the cause of breakages and the remedial methods adopted.