Steel Curved Pipe Jacking Construction under Complicated Conditions for a Curved Pipe Roof

The Gongbei tunnel is currently being constructed in Zhuhai, with a combination of curved pipe jacking roof for ground support and ground freezing waterproof applied, to guarantee the tunnel traverse under the Gongbei Port. This pipe roof is comprised 36 steel curved jacking pipe strings of 1620mm diameter with 355mm similar to 358mm gap between adjacent strings. The pipe jacking construction has been faced with various challenges due to the site conditions of multiple soft soil and high groundwater pressure. These challenges include risks of excessive soil deformation, possibility of path deviation, excessive jacking force, leaking of pipe joint seals and failure of gasketed launch seal and reception. This paper will provide an overview of this project and summarize the most challenging aspects they faced. The relevant techniques applied during construction, such as selection of pipe jacking machine, controlling trajectory of close curved pipe jacking, sealing test of pipe joint, pipe jacking mud in rich salt multiple formations and pipe jacking reception device under high underground water pressure are introduced in detail last.