Studies On Uplift Mechanism And Bearing Capacity Calculation Of Branch Pile

The branch pile has advantages of high bearing capacity, wide application rangeand obvious economic benefit, etc., if it is used as the basis for the uplift oranti-floating design, can bring considerable economic benefits, safe performance andproject cost reduction. However, as a new type of pile, the theoretical researches andengineering applications of the branch pile in the uplift are not much. This is closelyrelevant with less research of the uplift mechanism and engineering trait of the branchpile. Therefore, research the uplift bearing of the branch pile is very meaningful.On the basis of reading and analyzing the related domestic and internationalliterature, the uplift bearing mechanism and bearing capacity calculation of the branchpile were studied via theoretical and systematic laboratory model test in this paper.Research contents include:First, based on the reference to the pedestal pile failure surface, the slip surfaceassumption with power function and the limit equilibrium method were used inderiving a ultimate uplift bearing capacity formula of the single-plate branch pile.Secondly, three groups of the branch pile in sand under uplift loading laboratorymodel test were undertaken to study the influenction of the plate number, the platedepth and the plate spacing on the uplift bearing mechanism and bearing capacity.The studys show that the uplift bearing capacity of straight pile is smaller than thebranch pile under the same conditions; The uplift bearing capacities of the straightpile and branch pile have substantial decreases when the overburden reduces; Theuplift bearing capacity of the double-plates branch pile increases with the platespacing under the same bury and load conditions. Third, the involved pile body forces and the earth pressures around the pile in thewhole model test were analyzed. The results show that, in the aspect of the pile bodyforce: the plate resistance and the lateral friction exist complementary relationship inthe entire loading process; The difference of the pile spacing are directly related to theplay of the carrying capacity, there is a significant time effect in the playing of thebearing capacity of the upper and the lower plates. In the aspect of the earth pressuresaround the pile: there is a trend of formation of cavity under the pile bottom or platebottom, and it leads to unloading situation in the sand.