高速铁路CFG桩筏复合地基沉降特性试验研究

对京沪高速铁路CFG(Cement Fly-ash Gravel)桩筏复合地基进行了现场试验研究,实测了桩顶、两桩中心、四桩中心处桩间土体的沉降值及路基面沉降值,深入分析了桩顶、两桩中心、四桩中心处桩间土体的沉降及路基面沉降随荷载和固结时间的变化规律,对CFG桩筏复合地基的沉降特性进行深入研究,得到以下主要结论:沉降主要发生在加载期间,即沉降快速发展阶段,期间桩顶、桩间土沉降均占总沉降的60%左右;CFG桩加固区沉降约占相应总沉降的1/4,下卧层沉降约占3/4;路基面沉降曲线成锅形分布,路基中间沉降量较大,路基两侧较小;地基沉降—荷载—时间规律可分为3个阶段,即沉降快速发展阶段、沉降发展阶段和沉降基本稳定阶段;超载预压对于减少工后沉降是必要的,预压3个月后,地基沉降基本上趋于稳定,路堤的预压静置时间应不小于3个月。

Experimental study on settlement performance of CFG pile-RC mat composite foundation of high railway

CFG pile-RC（Reinforced Concrete） mat composite foundation of Beijing-Shanghai high railway is studied experimently,and the settlements beyond piles,between two piles,in the centre of four piles and on the top of embankment are tested and analyzed deeply.Also,the settlement performance of CFG pile-RC mat composite foundation is researched.Finally,main results are summarized as below： Firstly,main settlements appear when loading,which is in the stage of quick development,and the settlements beyond piles and between piles are about 60 percent of the total settlement in the step;Secondly,the settlement of reinforced part accounts about 25% of the total settlement and the settlement of underlying stratum accounts about 75%;Thirdly,settlement curve of embankment surface is the same shape as the pot,and the settlement is larger in the middle and is smaller at the edge of the embankment;Fourthly,settlement-loads-time law of the embankment settlement is included as three stages as quick development,development and relative stability;Finally,embankment settlement is relative stable after pressurized in 3 months.Therefore,it is necessary for decreasing settlement to load in advance,and loading time is longer than three months.