| With the development of Communication and transportation in our Country, more large-span bridge are being built or to be built, The percentage of foundation cost in the project is become larger as the qualification for the bridge foundation is getting more critical.The caisson foundation is kind of foundation that sink to the designed elevation by self-weight surmount the side-wall friction, then filled the caisson tank as pier and foundation of bridge or other structures. It can be sank to very deep underground, good integrity and stability, as well as large capacity area and can bear large vertical and horizontal loads. The shortcomings of large caisson are that its big size, deep depth, lots of compartments, construction difficulties, and it more easier to be offset, large subsidence and high cost.Considering the disadvantages of caisson, Highway Corporation of Anhui province put forward a brand new foundation style—Rootstalk Foundation, a research group was set up and a national patent was applied. Its construction process are: obligate jack hole in the caisson, jacked the prefabricate rootstalk (RC beam or steel beam)into the soil after the caisson sank to the design elevation, assuring that the rootstalks are fixed with the caisson then a root-simulated foundation is completed. The load capacity of ambient soil is greatly activated because of the penetration, compression and stress pervasion of the jacked rootstalk. Then the foundation base is just like being "unloaded", its bearing load capacity is greatly improved. The rootstalk foundation is suitable and potential especially in deep coverage stratum .As a part of the Rootstalk foundation research ,the paper introduce contrast of the vertical load and pull capacity, horizontal push capacity between the rootstalk foundation and the common caisson by means of 3-D FEM software analysis. The analysis shows that the rootstalk foundation has great practical potential and its mechanical behavior are preliminarily discussed.
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