Study On Mechanical Properties And The Load-bearing Property Of Uplift Pile In Loess Area

Uplift piles as an important pile form,is commonly used in the China.It has been widely used in the underground garage,underground shopping malls,subway construction.And it's more common in the coastal areas so that the pile bearing performance research is more deep in this area,With the development of the western region,the development of underground buildings is becoming more and more extensive,and the anti-floating design needs to be solved urgently.In the western loess area,the research on the uplift piles is relatively backward,so the uplift piles Bearing capacity research and discussion is necessary.This thesis is a extension of the experimental study of the single pile in the existing project.Through the field test,the drawing performance of the single pile in the loess area has been partly concluded,and that research on the bearing capacity of the pileField tests are difficult to carry out.Therefore,based on the field test,this thesis makes a further study on the bearing capacity of single pile and pile group in loess strata by numerical simulation of finite element analysis software ABAQUS,and focus on the load Mechanism and bearing capacity of the region for the design and construction of the pile foundation.The main conclusions are:1.In the loess formation,the single pile to withstand the load on the pull,the pull bearing capacity provided by the pile side friction,pile side of the friction to play with the depth of the pile gradually play,showing a great non-linear,with the pile The increase of the pile length,the pile diameter and the pile body strength can increase the tensile capacity of the single pile,but the increase of the bearing capacity is not improved obviously after increasing to a certain extent.2.The effect of horizontal load on the bearing capacity of single pile is adversely affected.With the increase of horizontal load,the bearing capacity of single pile is reduced.The magnitude of the pile-side friction at the same depth increases with the increase of the horizontal load.When the horizontal load increases to 0.4 times the horizontal ultimate bearing capacity of the single pile,the degree of friction of the pile side will not increase.In the group pile foundation,the role of horizontal load,the impact of the pile bearing capacity of a greater impact in the design of the need to strengthen the anti-pull bearing capacity of the angle pile.3.In the loess formation,the bearing capacity of the uplift piles is lower than that of the generalized slabs.The results show that the friction load in the loess strata is more Fast,in the pile relative displacement of 1-2mm,you can play,and generally cohesive soil,pile and soil displacement to 6-7mm,the pile side of the limit side of the friction to play out.4.Compared with the single pile,the pile group effect is more obvious than that of the single pile.The bearing capacity of the pile in the pile is different,and the displacement of the pile is larger than that of the pile The increase of pile length will reduce the displacement of pile group and increase the pile length so that the influence of pile and soil will increase.The change of pile spacing will increase the pile-And the interaction between pile and pile in pile foundation is weakened,and the stress superposition effect of pile soil is weakened,which can obviously improve the bearing capacity of pile group.,The increase of the load-carrying capacity of the pile group foundation is not big.As the number of piles increases,the influence of pile and pile increases,and the effect of pile group is more obvious.5.The group pile foundation in the load on the load to show a more obvious uneven distribution characteristics,which bear the largest pile load,edge pile,the middle of the pile minimum.This nonuniform distribution characteristic decreases as the load increases.