Uplift Drawing Bearing Characteristics Research Of Single Screw Anchor Pile

Screw anchors are commonly used as underground anchorage supported uplift bearing capacity,because of some benefits such as instillation efficiency and strong bearing,they are widely used in basic engineering construction included building and construction,roads and bridges,photovoltaic power station.Under vertical load,pile-soil interaction and defected mode of screw anchor with the spiral leaf blade are more complex than resistance pile with equal section.But for now,there is less study about screw anchor uplift bearing capacity at home and aboard,so the bearing capacity mechanism in the process of uplift is not clear.Additionally,related specifications have not included screw anchor,so design of screw in engineering practice is still not uniform,especially for the determination of extreme limit of anti-lifting bearing capacity.Therefore,it is necessary to study uplift bearing characteristics of single screw anchor.In this paper,numerical simulation method has been used to analyze the influence of blade diameters,blade angle and embed depth on single screw anchor bearing capacity and detected mode under drawing process,putting forward screw anchor calculation formula of uplift capacity.The uplift bearing capacity of single screw anchor increase with increasing blade diameter,but there is no influence on detected mode;Blade angle and embed depth effect the detect mode of single screw anchor under uplift load.Based on the difference of blade angle,there are three types of screw anchor detected mode.Combine the effect of embed depth,soil friction angle and blade angle on the angle of failure surface with vertical,single screw anchor uplift bearing capacity computing models are established.Laboratory model tests are carried out to analyze curve of Q-s embed in different depth and judge the ultimate uplift bearing capacity of model pile,the model pile is single screw anchor with soil pressure gauge.Through the collection of serial data of soil pressure gauge under stepped loading,the earth pressure distribution upper and lower surfaces under uplift drawing process is analyzed.Contrast the data of the ultimate clearing capacity extracted from laboratory model tests and literature with data computed by the formula established in the paper,the results match well,checking the accuracy of the formula.The formula of single screw anchor uplift bearing capacity proposed in this paper from the detected mode revealed the relationship between blade angle,embed depth and soil fraction angle with ultimate bearing capacity,targeted solved the computational problem about single screw anchor uplift drawing ultimate bearing capacity,overcome lacks of calculations lesson from traditional pulling resistant pile,provide theoretical basis for the design of screw anchor.