| Based on the application status of floating platform technology in the construction of cross-deep lakes, reservoir or sea bridge at home and abroad, taking the pile foundation of large bridge in deep lakes and reservoirs without any large floatings crane and barges as study object, this areicle discusses two major technical challenges in the construction of rock-socketed piles of bare rock in deep-water: First, selection and integrated design of floating construction platform and lifting equipment; Second, accurate positioning and laying of the steel casing pile.At first, the technology of building floating drilling platform adopting multi-purpose pontoon floating to replace the conventional 60 floating box is put forward. And its gantry crane and drilling platform is integratedly designed. The rationality of the structural stability and resistance to overturning floating drilling platform system composed by multi-purpose floating box is verified by calculating. It has the advantages of simple construction process, less investment of building materials, low operating costs as well as the structural safety and stability, etc. and provides a reference and learning.for the construction pile foundation work in the deep-water.Then, on the basis of project experience ang existing theory, this article establishes a mathematical model of the drilling platform and a single steel casing by using the finite element theories, and carries out analysis of loads and boundary constraints . At the same time, to pontoon platform force balance principle as a basis for the floating platform, checking the rigidity of approximate formula method, in considering the platform, symmetrical anchoring conditions, the establishment of a floating platform, flexible dynamic model of the water for further analysis of the most unfavorable conditions the stability of the platform to float downward box lay a theoretical basis.At last, "Planting pile" technology of steel guide-well casing is proposed. First, punch on the platform bedrock with the impact drill until the design elevation of the steel casing to form a positioning hole. Then, a long steel casing is put in place as a whole section by section. Finally, pour the underwater concrete cast around the outside to form rock-socketed steel pipe piles. It ensures flat position and vertical degrees of the casing embedded rock laid, and improves the stability of steel casing of underwater construction. Also, it provides experience and provides a basis for the construction technology of laying steel casing on bare rock surface of deep-water districts.This research has been successfully applied to the construction of small Jinshan Bridge construction, and achieved good economic, social and environmental benefits. |
