Research Method Of Ultimate Bearing Capacity Of Pile And Testand Determination Method Considering The Effect Of Pile Side Resistance

Pile foundation, as one of the most widely used form of foundation, which has a variety of types and forms. Pile bears the upper load mainly and transfers the vertical load to the deep soil layers. Therefore, ultimate bearing capacity calculation is the most important factor in pile design. Currently, specifications have pointed out that the pile side friction resistance and end resistance are two inter-independent parts and do not exist any relationship. The ultimate bearing capacity of pile foundation is side resistance plus end resistance simply. Interestingly, some data from field tests and indoor model test demonstrated that the friction resistance and end resistance are not two inter-independent parts completely. That is to say, there exists some interactions in some ways during pile loading test. This interaction increases pile side resistance greatly, which leads to impacting on pile ultimate bearing capacity. Then the pile side resistance enhancement effect is simulated by indoor model test. With the help of the static load test of pile, the pile side resistance enhancement effect influence on side friction resistance is observed. The key factor, pile radius, is analyzed. Finally, the limited analysis method is introduced and simulated the interaction between tip resistance and side residence. Thus, new vertical bearing capacity calculation which takes into consider the interaction between side resistance and end resistance is proposed.Firstly, based on the indoor model test, the side resistance enhancement effect is verified by monitoring side resistance near the pile tip. Secondly, the pile radius effects on side resistance enhancement is discussed which shows that: side resistance enhancement effect increases with increasing pile radius linearly. On this basis, the influence of pile-soil relative displacement at pile tip, the soil strength under pile tip, the digress of pile end resistance and complexity of soil are studied. Based on the Meyerhof deep foundation failure model and upper-bound method of limit analysis, the bearing capacity calculation method which can take the shaft resistance enhancement effect into consideration is proposed. Then, the rule of shaft resistance enhancement effect is explored by analyzing the influence factors. Finally, the feasibility of the proposed method is able to be assessed by a comparison with traditional method.