Experimental Study On Bearing Capacity Of Large Bearing Capacity Friction Piles

As a foundation with high bearing capacity and small control of settlement deformation,the pile foundation has been widely used today,with mature technology and universal applicability.However,the current bearing capacity of most single piles is basically less than 1,000 tons.For a high-capacity pile of more than 1,000 tons,a complete set of normative research system has not been formed,and the actual research on the bearing characteristics of piles under high stress conditions is lacking.Engineering case.This paper takes a super high-rise project in Yinchuan area as the research object,and uses the combination of theoretical analysis,static load test and numerical simulation to study the bearing performance of high-capacity friction piles.The details are as follows:(1)By referring to the relevant pile foundation theory,the pile foundation load transfer mechanism is studied,and the advantages and disadvantages of shear displacement method,finite element method and load transfer function method are compared and summarized.The load function method is used to meet the friction bearing pile with large bearing capacity.(2)The static load test is carried out at the project site,and the QS and S-logt curves of the pile foundation are measured.The average bearing capacity of the large-capacity friction piles with a length of about 45m and a pile diameter of 1m is 30833kN.The piles are in the area.(3)The pile internal force test is carried out by embedding the steel bar stress meter,and the stress-strain data is processed to obtain the pile side friction curve.The analysis shows that the pile side frictional resistance curve is a quadratic function curve;It is about 30m?45m in the middle and lower part of the pile;the lateral resistance curves of the three test piles are similarly changed,and they all appear in a certain position of the pile body and maintain a relatively stable trend;the lateral frictional resistance of the pile is related to the soil layer property,and the soil is measured.The lateral frictional resistance value of the layer is obviously larger than the recommended value of the specification,and the ratio of the standard is 1.4-2.6 times,which indicates that the bearing capacity of the soil layer in this area is very good.The large-load bearing friction pile can bear the large load,which is the best in the pile foundation.Choose one.(4)Using Abaqus combined with engineering test to establish a model,further study the bearing capacity of high-capacity friction piles,and obtain:the high-capacity friction type pile side resistance first,the end resistance and the pile side friction resistance first to the limit;the pile end limit The resistance is 4180kN;the lateral friction resistance of the pile is 25820kN and the end resistance is 4180kN.The ratio of the two is 86%and 14%.Further research has found that the high-capacity pile end resistance has a strengthening effect on the side resistance:the pile end soil layer makes the pile end resistance play differently,and the pile end resistance will affect the pile side resistance,which generally causes the pile side friction resistance to increase and improve.The amplitude is related to the soil properties of the pile end.The lower the compressibility of the soil at the pile end,the greater the increase of the limit side resistance,that is,the strengthening effect of the end resistance on the pile side resistance is more obvious.In this paper,through the analysis of the load transfer mechanism of large bearing capacity friction piles,the ultimate bearing capacity of single piles and the frictional resistance,the bearing behavior of pile foundation is studied,which is intended to provide certain basis and reference value for this kind of engineering design.