With the smooth pouring of the final concrete into the mold, the S4 # pier cover beam of the Shazaili Waterway Bridge in the Lion Ocean Channel project has been successfully poured. At this point, the construction of all four concrete permanent pier cover beams of the bridge has come to a perfect end, and the construction of the lower structure has entered a new stage of upper structure installation. The Shazaili Waterway Bridge is constructed by CCCC Second Highway Engineering Co., Ltd. and is a key project of the Lion Ocean Channel. The bridge adopts a variable height double-layer variable cross-section three main truss continuous steel truss structure, with a total length of 660 meters. With the completion of the cover beam construction, the installation project of the 35000 ton steel truss beam is expected to start in July this year. However, unlike conventional bridges, the double-layer variable cross-section three main truss structure of the Shazaili Waterway Bridge brings stronger traffic capacity, but also poses three major technical challenges for the installation of the upper structure. One is the difficulty in controlling the assembly of ultra long cantilevers. The project plans to use double cantilever assembly technology, with a maximum cantilever length of 75 meters for the side span and 135 meters for the mid span. In such a long cantilever state, the balance of internal forces in the structure is coupled with the accuracy of linear control, and even a slight mistake can affect the completion of the bridge. To this end, the project team needs to establish a complete bridge model for full element simulation analysis of the installation process, repeatedly verify the internal forces of the members, in order to guide the development of refined construction organization design and control methods. The second requirement is high precision for the closure of large cross-section members. Due to the huge cross-sectional size of the members and the varying effects of temperature, wind load, sunlight, and other factors on the three main trusses during closure, it is extremely difficult to accurately control the spatial coordinates of the closure point. How to achieve "millimeter level" coupling in complex environments is the core of the team's next technological breakthrough. Thirdly, the arrangement of temporary support piers is constrained by multiple factors. The construction of temporary support piers for side spans needs to avoid obstacles such as mangrove conservation areas, existing water gates, embankments, local roads, and underground pipelines, which greatly limit the working space; The mid span temporary support pier is limited by the width of the waterway and cannot be deployed on a large scale. At the same time, the single pile bearing capacity is as high as 1446 tons, which puts forward ultimate requirements for the stability of the support system. At present, the control engineering of the Lion Ocean Passage project - the east and west cable towers of the Lion Ocean Bridge have been successfully capped, and the construction of two anchorages is steadily progressing. The project has entered a new stage of upper structure construction. As the first double-layer river crossing channel in the the Pearl River Estuary, the Shiziyang Channel will effectively ease the traffic pressure of Humen Bridge and Nansha Bridge after completion, adding important support to the "1-hour traffic circle" of Guangdong Hong Kong Macao Greater Bay Area. The construction difficulty of this project is high, with multiple technical indicators ranking among the top at home and abroad. Its construction experience will also provide reference for China's future cross sea and cross river composite three-dimensional transportation projects. (New Society)