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为了解路堤荷载作用下CFG桩-筏复合地基沉降变形特性,在京沪高速铁路凤阳试验段进行了沉降变形现场试验.设置沉降板、观测桩和测斜管,分别监测地基面桩土沉降、路基顶面沉降和地基侧向水平位移,分析了沉降变形随路堤填筑高度和时间的变化规律,探讨了双曲线沉降预测方法.研究结果表明:CFG桩-筏复合地基沉降随路堤填筑高度和时间的增加而增大;路基经过6个多月的静置后,沉降已趋于稳定;复合地基总沉降量小于15mm,桩土沉降差小于2mm;路堤坡脚线外1m处的地基侧向最大水平位移小于4mm;采用双曲线法进行路基沉降预测是可行的,且预测精度较高.采用CFG桩-筏复合处理后的地基总沉降、沉降差和水平位移均较小,路基沉降稳定较快,能够提高路基的稳定性并缩短工期.
In order to understand the settlement and deformation characteristics of CFG pile-raft composite foundation under embankment load, a field test of settlement deformation was conducted in Fengyang test section of Beijing-Shanghai high-speed railway. Settlement plates, observation piles and inclinometers were set up to monitor the pile-soil settlement , The top subgrade settlement and the horizontal subsidence of the subgrade are analyzed.The variation regularity of subsidence deformation with embankment filling height and time are analyzed and the prediction method of hyperbolic subsidence is discussed.The results show that the settlement of CFG piled raft composite foundation The height and time of the embankment increased. After subsided for more than 6 months, the subsidence tended to be stable. The total subsidence of composite foundation was less than 15 mm, the difference of pile-soil settlement was less than 2 mm. Lateral maximum horizontal displacement is less than 4mm.The prediction of subgrade settlement by hyperbolic method is feasible and the prediction accuracy is high.The total subsidence, settlement difference and horizontal displacement after CFG pile-raft composite treatment are small, Stable faster, can improve the stability of subgrade and shorten the construction period.