Study On Bearing Capacity Of Uplift Pile With Enlarged Base Of A Project In Eastern District Of Zhengzhou

As the main form of variable cross-section uplift piles,belled piles have been gradually applied to the foundation of buildings(structures)which need to resist uplift loads.Compared with the pile with equal cross-section,uplift pile with enlarged base only improves the uplift bearing capacity by changing the cross-section of the pile,and the effect is remarkable.Therefore,it is of practical significance to study the bearing capacity and mechanism of uplift pile with enlarged base.(1)Comparing various calculation methods and optimizing related methods,the results are close to the reality,but each method has its limitations and does not have universality.Based on the analysis of the calculated value and the static load test results,it is concluded that the contribution rate of each extended metre to the uplift bearing capacity of the pile is 4.2 times that of the non-expanded section,which further proves the advantages of the belled pile.(2)Analyzing the report of pile test,the mechanism of action of belled pile can be divided into the following stages: in the initial stage of loading,when the uplift load is small,the frictional resistance of pile side plays a role,the load-displacement curve is approximately linear,and the soil around the pile is in the elastic stage;under continuous loading,the displacement growth rate of pile top accelerates,the enlarged head begins to play a role,and the soil around the pile is in the plastic stage.(3)The loading process of belled pile is simulated by FLAC 3D.The results show that with the increase of load,the plastic zone first appears at the top of the pile,then at the enlarged head,and the plastic zone extends upward along the enlarged cone.By changing the diameter and length of the enlarged head,the numerical calculation shows that when the enlarged pile head is twice the diameter of the equal section pile,the uplift pile plays the most significant role.