ABSTRACT
India’s longest river bridge (Dhubri-Phulbari Bridge) will be constructed over the river Brahmaputra in the state of Assam/Meghalaya in northeast India. Based on the geotechnical investigations at the site, the entire bridge is proposed to be constructed on pile foundations. The integrity of the piles was verified through the assessment of Cross Hole Sonic Logging (CHSL) tests at the site. The arrival time and signal energy of the stress pulses were used to inspect the pile integrity, and the position and extent of defects, if any. The tests were conducted while maintaining pulse wave speed (>4000 m/s) and recommended signal strengths. Usually, a pile is classified as acceptable if the first arrival time increases up to 20% and the energy reduction is <9 dB. The interpretation of CHSL test data identified a few defective piles attributing cross-sectional changes, honeycombing, and poor concrete quality. This paper presents a detailed case study to handle such an important mega project showing the effective use of the CHSL test.
