Analyses & Construction Challenges of Deepest Bored Cast-in-Situ Raker Piling for Bridge Across Volta River, Ghana-PPT Presentation

PPT Presentation

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The presentation describes the design and construction of the 300 m Volta River railway bridge in Ghana, part of a 92 km rail link between Tema and Akosombo. The bridge has five 60 m spans and a steel-composite superstructure supported by vertical and raker pile foundations bearing on rock.<br /><br />A major design change followed Ghana’s 2018 building-code revision, which raised the seismic peak ground acceleration for Zone 3 from 0.16g to 0.35g. This made seismic forces critical and prompted adoption of raker piles at the piers. The 1:5 raked piles increased lateral capacity while reducing the proposed diameter from 2.0 m to 1.6 m.<br /><br />Construction was complicated by variable rock-touch levels (RTLs), deep sand layers, and the need to execute marine piling with temporary platforms and barge-mounted equipment. Because RTL changes affected pile design and lateral forces, crews monitored each pile’s rock level and obtained design approval before lowering reinforcement cages and concreting. Liner driving sometimes met high resistance, requiring internal boring; early bottom sloughing was addressed by increasing the sand-plug length.<br /><br />The construction sequence included installing temporary piles and platforms, driving liners, drilling and socketing 10 m into rock with a reverse-circulation drilling rig, lowering reinforcement cages of up to 76 m, and tremie concreting. Thirty piles were completed in about six months. Lateral load testing was used to demonstrate pile-group performance and validate spring stiffness.<br /><br />The project highlights the importance of coordinating geotechnical investigation, design checks, and site operations in real time, especially for unfamiliar marine foundations and highly variable ground conditions.

Keywords

Volta River railway bridge

Ghana railway bridge

seismic design

raker piles

pile foundations

marine piling

rock socketing

reverse-circulation drilling

lateral load testing

geotechnical investigation