CENTRIFUGE MODEL TESTS AND NUMERICAL SIMULATION OF LOAD SHARING LAW FOR COMPOSITE EMBANKMENT WITH LONG AND SHORT PILES

The load sharing law of composite embankment with long and short piles under embankment load is studied through centrifuge tests and three-dimensional finite element methods.Four centrifuge model tests are conducted on the purpose of exploring the variation curves of pile-soil stress ratios of long pile and short pile with a given length ratio of pile in stepped loading process.The relationship between the axial forces of long pile and short pile measured in each test and the settlement of soft soil is conducted.Based on the fundamental parameters of the centrifuge model tests,three-dimensional finite element models are established to carry out the comparison with the centrifuge tests results.The Gibson subgrade is adopted to factually simulate the strength feature of soft clay foundation in the centrifuge field,which gradually increases with depth as closer to the bottom of the test box.Comparison of the calculated results with measured centrifugal model test results identifies the rationality of the established model.Furthermore,the pile-soil load sharing law of this composite embankment with long and short piles which is applied to the layered foundation with bearing stratum is studied through this numerical method.The study results show that the long piles take more embankment load with the increase of embankment load,while the short piles and soft soils both take less and trend to be stable.The larger the length ratio of long pile to short pile,the more the load sharing ratio of the long piles take.The composite embankment with long and short piles is better in reducing embankment settlement and the long piles shares more loads in the layered foundation with bearing stratum.