Rotary Kelly Drilling for the Bored Pile Foundation of the Hong Kong Zhuhai Macao Bridge-Paper

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The Hong Kong–Zhuhai–Macau Bridge required exceptionally deep offshore foundations in challenging ground conditions. For the deep-water section, Bauer used Rotary Kelly Drilling (RKD), selected by the project joint venture as a faster, more economical alternative to Reverse Circulation Drilling (RCD).<br /><br />Between April 2013 and December 2014, four BG 40 rigs installed 230 bored piles, 2.3 or 2.5 metres in diameter, across 32 piers. Although tender estimates anticipated piles up to 85 metres deep, some reached approximately 115 metres. Work was complicated by restricted hours, a seasonal suspension of rock drilling to protect dolphins, and marine logistics that reduced productive time.<br /><br />The geology comprised marine clay, alluvium and deeply weathered granite, with competent rock sometimes far below expected levels. Predrilling and core sampling at each pile location identified ground conditions and informed pile design. Where rock sockets would have made piles impractically long, 38 piles were redesigned as shaft-grouted friction piles. A full-scale, instrumented offshore load test established friction capacities in the varied soils and weathered rock.<br /><br />Construction required reusable steel working platforms, support barges, carefully coordinated transport, slurry management, heavy reinforcement cages and large concrete deliveries. Quality control included sonic logging of every pile, interface coring, and additional coring on selected piles. Testing confirmed sound concrete and clean pile toes; remedial toe grouting was used where needed.<br /><br />The project demonstrated that RKD could construct large-diameter offshore piles substantially faster than RCD—about three times faster in comparable piles up to 50 metres, with an even greater expected advantage at greater depths. Despite the added platform requirements, faster construction and shorter permanent casings reduced overall costs. The completed foundations met the project’s technical requirements, illustrating the method’s suitability for major offshore bridge works.

Keywords

Hong Kong-Zhuhai-Macau Bridge

offshore foundations

Rotary Kelly Drilling

deep-water piles

BG 40 rigs

bored piles

shaft-grouted friction piles

marine geology

load testing

sonic logging