The Study Of The Squeezed Branch Pile Of Anti-pull And Energy Dissipation Performance Under Earthquake

With a large number of the application of the branch pile in engineering, the engineers begin to pay more attention to the characteristic Dynamic Pile. Based on shaking table test of the dynamic interaction of squeezed branch pile - soil - frame structure, using the finite element analysis software MARC to research the seismic performance of squeezed disk pile system. Numerical calculation results indicated that its time-history curves of acceleration at the top of structure is in good agreement with the experimental curve under the excitation of the X-way and X, Z two-way seismic wave, which verifies the reliability and accuracy of numerical stimulation. The finite element model of the straight pile system is also established under the same condition, and contrast research is done between calculations of those two different pile-type system .The results are as follows :(1) It is figured out that the both the side friction resistance of the pile and the end resistance force of the disk composes anti-pulling force of the squeezed disk pile. The percentage of the end resistance force taking rises when the dynamic load increases, and the load is mainly transferred through the disk pile. However, the anti-pulling force of the straight pile is much smaller than the disk pile because it is provided by friction resistance of its pile shaft only, and this difference becomes more distinct under the excitation of the X, Z two-way seismic wave.(2) It is also indicated that the squeezed disk pile bears alternating tension and compression loads when the building vibrates under earthquake, and the pulling "stress bubble" in disk-upper soil grows when the displacement at the top of the structure increases. It proves that the pulling force is mainly transmitted through the disks which effectively dissipate part of the seismic energy. In addition, the group pile base structure which forms by disk piles can make a full use of its'anti-pulling and anti-pressing loading potential, this structure also have a better anti-capsizing capability , which the swing of its'upper structure can be mitigated and the capsizing of the whole structure be prevented.(3)Under the same excitation of the earthquake wave, the swinging of upper structure using the disk pile's is less and the collapse torque caused by the displacement of the gravity of the structure is also smaller. Not only can it lighten the damage of the upper structure, but can also make a more effective safe-protect.(4) It indicates that the anti-shearing capability is the weakness of both the branch pile and other piles, it is also suggested that the combination of the use of the branch pile and the raft foundation or box-based pile shall be adopted on high-level seismic design, in order that the shock absorption function of the branch pile can be fully expressed.New technical methods and basis for revealing the pile base's anti-pulling and anti-shocking mechanism are provided by this study, and theoretical and practical significance is also rendered on disaster prevention and reduction.