Study On Anti-pulling Vertical Characteristics Of The Screw Piles In Sandy Class Foundation

Screw filling pile is a new kind of variable cross-section profiled pile foundation technology.It is on the basis of long spiral drilling piles, developed in the long spiral drilling filling pile soil compaction and earth into a hole in the way of optimization for the screw piles of the whole earth into a hole, the pile side form by smooth cylindrical pile side form to screw pile side form, thus greatly improve the pile side friction.The existence of the screw increases the effective bearing area of the pile body, at the same time between threads of the screw piles and soil has great mechanical occlusal force, so the screw piles can significantly improve the uplift bearing capacity of single pile.However, the ability for screw piles applied in the study of and engineering practice is less, in order to better for the promotion of this kind of tension technology, so it is necessary to the pull-out bearing performance and mechanism of screw piles for this paper.On the basis of equivalent linear pile diameter and thread pile, different spacing of piles, compares the two sets of indoor model test research of sandy soil were analyzed in the type of foundation top loads under the laws of uplift bearing performance.Firstly, based on the similar theory of model test, the use of a certain proportion of similar, relationship, with sandy soil to simulate the foundation soil, at the same time, based on the research of the predecessors’ pull-out test on the basis of the design thread, straight pile, test model slot and load device and data measurement process.Secondly, on the basis of the measured data of indoor model test, such as comparison, respectively analyzes the straight pile diameter and thread pile, different spacing of uplift bearing capacity of piles, axial force of pile, pile side friction of pile and soil stress characteristics*focus on the uplift bearing capacity, axial force of pile and side friction calculation, draw the corresponding curve, and some useful conclusions.Finally, the design of screw spacing parameters has carried on the preliminary discussion, on the basis of the existing under vertical loads and the screw thread, and a method for determining the bearing capacity of pile is proposed to estimate screw piles calculating formula of single pile bearing capacity of uplift.