Centrifugal Study On Bearing Capacity Of Foundation Of Caisson In Saturated Sandy Soil

China has rivers criss-crossing and large sea area, ultra-large caisson in successively emerging in pace with the expansion of bridge construction towards board water area, open ocean, complication of geological conditions and increase of depth. Such projects have met a lot of new technical difficulties during design and construction, while the practice of deep ultra-large caisson is very limited in China at present. It requires to learn from existing foreign advanced results and technologies of deep water foundation, as well as take our actual situation and specific bridge engineering in consideration for earnest study. To avoid any uneven settlement of foundation caused by insufficient foundation bearing capacity, and meet the requirement of high speed, high ride performance and high stability for high-speed passenger transportation railway, it’s necessary to perform study of the bearing capacity of caisson in saturated sand.Based on the newly built Shanghai-Nantong railway Yangtze River Bridge, this paper performs analysis on the load-settlement curve of caisson at different depth and basic width in saturated sand by indoor centrifuge test, numerical simulation and theoretical analysis and draws the following conclusion:(1) 8 centrifuge tests have been carried out to monitor and analyze the test data. It points out that along with the increase of load, the nolinear of load-settlement curve grows; The load-settlement curve can approximately be simulated with hyperbola model; When the foundation is embedded superficially, visible point of inflection appears in the load curve. When it embedded deeply, the point of inflexion of load-settlement curve is less visible than superficially embedded.(2) With different embedded depth and in pace with the increase of superior load, the load-settlement curve shows nolinear change. Along with the increase of foundation embedded depth, the load-settlement curve moves outside gradually. It means the bearing capacity of foundation increases along with the growth of foundation embedded depth.(3) It infers the calculation formula of correlativity between foundation bearing capacity and relative embedded depth & width of foundation based on the centrifuge model test.(4) Compared the results of centrifuge model test results with TB 10002.5-2005 "Code for Design on Subsoil and Foundation of Railway" and GB50007-2011 "Code for Design of Building Foundation", it figures out that the difference between result of centrifuge model test and calculation result of the specified calculation method is large, as the result of specified calculation is small and tends to be safe.