中文摘要：

采用离心模型试验和三维有限元法,探讨路堤荷载下长短桩组合路堤桩的荷载分担规律。共进行4组离心模型试验,得到不同桩长比时长桩和短桩的桩土应力比随分级加载过程的变化曲线,以及相应的长桩和短桩桩身轴力的传递规律。基于离心模型试验的基本参数建立三维有限元模型,采用Gibson地基模拟离心场中软土地基强度沿深度方向逐渐增大的特性。计算结果与离心模型测试结果的对比验证模型建立的合理性;并且进一步研究长短桩组合路堤桩应用于存在持力层时的层状地基中的桩土荷载分担规律。研究结果表明：随着荷载的增加,长桩分担的荷载逐渐增大,而短桩和桩间土分担的荷载逐渐减小,且都趋于稳定值;桩长比越大,长桩分担的荷载越大;存在持力层时的层状地基更有利于长短桩组合路堤桩加固效果的发挥。

英文摘要：

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.