高速铁路湿陷性黄土桩筏复合地基沉降控制效应

Settlement Controlling Effect in Pile Raft Composite Foundation on Collapsible Loess in High Speed Railway

摘要:

为研究和分析高速铁路荷载作用下刚性桩桩筏复合地基控制湿陷性黄土地基沉降的效应，采用离心模型试验的方法对不同桩间距设置条件下的刚性桩桩筏复合地基进行了模拟试验.试验研究表明：湿陷性黄土地基无法满足高速铁路轨道结构对路基工后沉降的要求，需要加固处理.随着桩间距由2倍增至6倍桩径，地基总沉降量及工后沉降量显著增大且变化速率较大，桩间土对桩体的负摩阻力增大.桩间土与桩体相对位移中性点位置随着桩间距的增大而显著降低，工后阶段中性点位置变化趋势为逐步上升并趋于稳定.工后阶段筏板与桩体相对位移量呈减少并趋于稳定的趋势.差异沉降主要发生在施工阶段，桩筏复合地基工后阶段控制沉降及差异沉降的能力较好.

Abstract:

Based on the experimental study at home and abroad, the centrifuge model test is used to imitate pile raft composite foundation in different pile spacing to research and analyze the settlement controlling ability of pile raft composite foundation on collapsible loess ground in high speed railway. The research results show that collapsible loess ground which can not meet the request on settlement after construction in track structure in high speed railway need be reinforced. The settlement after construction, differential settlement, pile soil load share ratio and the negative skin friction of pile get larger with the extending of pile spacing from two to six times of the pile diameter. The foundation settlement, settlement after construction, and the negative skin friction of pile get larger with the extending of pile spacing from two to six times of the pile diameter. Neutral point of the relative displacement between pile and soil drop with extending of pile spacing and rise to a stable level in post construction stage. Value of the relative displacement between pile and cushion drop to a stable level in post construction stage with extending of pile spacing. Differential settlement occurs mainly in construction stage. The differential settlement controlling effect of pile raft composite foundation is better in post construction stage.