Double Load Cell Self-balanced Pile Test And Finite Element Analysis About Super-tonnage Foundation Piles In Some Project In Beijing

With the developmet of economy internal and international, the super-long piles and super-tonnage piles are uesd more and more.The conventional test methods face great challenges in the tests.And sometimes they can not be carried out in the loading tests because of some limited condition.So the conventional loading tests can not keep the pace of the development of the foundation.The self-balanced method which can overcome disadvantage of the conventional loading test methods has some unique advantage such as advanced technique,saving time and expense, automatic test ,safety and credibility,lower site requirement. The main jobs and conclusions include:1. Some key technical problems including the determination of the balanced point position,embedmet of the load cell,conversion method,using for the pile foundations are researched to a certain extent in this paper.2. The design ultimate compressive bearing capacity was 40000kN,and the design ultimate uplift bearing capacity was 16000kN in the pile engineering in Beijing. The conventional loading test methods can't satisfy the requierment of the condtion and super-tonnage.So the double-load cell self-balanced method was uesd to test the compressive bearing capacity and the ultimate uplift bearing capacity.3. The practical project is numerically simulated by Plaxis 3D Foundation program to compare with the test and discuss the influence about the extending bottom pile.The research about the differnce between the extending bottom pile and the normal pile demonstrats t the xtending bottom pile can increase the ultimate bearing capacity to a great extent.4. Simplified calculation method and precise conversion method was used to convert the results of the test. Comparative Analyses between the two methods and the numerical computation demonstrats that the simplified calculation method can give higher precision,and this method can be used in the actual project.5. The numerical simulation method and some useful conclusions described in this paper can play a certain reference in this project.