高速铁路强夯地基沉降的离心模型试验研究

为准确掌握中等压缩性土地基在路堤荷载下的沉降变形规律,应用TLJ-2型土工离心试验机模拟强夯加固地基,研究高速铁路中等压缩性土地基的附加应力和分层沉降特征。通过与现场填筑试验对比,分析离心模型试验预测原型地基分层沉降的精度,提出沉降修正系数取值范围,为今后中等压缩性土地基加固技术优化提供借鉴。结果表明:路基基底中心应力比路肩下大,符合柔性基底应力分布形式;附加应力随地基深度增加而减小,强夯影响深度内附加应力衰减较快,而影响范围以下衰减减缓;铺轨运营550d后,地基工后沉降逐渐趋于稳定,工后沉降值远小于施工阶段地基的总沉降;离心模型试验预测地基单位分层压缩量的精度较高,而对于不同施工阶段离心模型试验预测地基沉降的精度存在差异,沉降修正系数的引入能够较为真实地反映现场地基沉降特性。

Centrifugal Model Test on Settlement of Dynamic Consolidation Ground of High-speed Railway

To accurately grasp the settlement deformation characteristics of medium-compressibility soil ground under the action of high-speed railway embankment load,the additional stress distribution characteristics and settlement property of the medium-compressibility soil foundation are analyzed by means of TLJ-2 geotechnical centrifuge tester and dynamic compaction to reinforce the shallow ground.The results are compared with those of the in-site filling test. The accuracy of the layered settlement of prototype ground predicted in the centrifugal model test is explored; and the range of modified settlement coefficient is put forward,which may provide reference for optimization of medium-compressibility soil ground reinforcement in future. The research results show that the stress of the subgrade center is greater than that of the shoulder,which is in compliance with the stress distribution of flexible foundation. The additional stress decreases with the increase of ground depth; and the additional stress within the depth range affected by dynamic compaction is reduced rapidly,while the reduction beyond the range slows down. After 550 days of operation,the settlement of foundation gradually becomes stable,and the settlement value is much less than the total settlement of foundation in the construction stage. The accuracy of the unit layered compression of the ground predicted in the centrifugal model test is very high,but differences exist in the accuracy of ground settlement predicted in centrifugal modeltest at different construction stages. The introduction of settlement modification coefficient can reflect the settlement characteristics of in-site ground in a more real manner.