路堤荷载下挤密螺纹桩复合地基沉降现场试验

Field experiment on settlement of compacted threaded pile composite foundation under embankment load

对新建兴泉铁路黄塘车站挤密螺纹桩复合地基的桩、土沉降及应力进行监测,分析了路堤荷载下桩、土沉降及差异沉降变化规律,桩土应力比与差异沉降关系。结果表明:桩、土沉降及差异沉降均随路堤填土高度的增加而呈线性增大;桩顶和桩间土应力随路堤填土高度的增加均不断增大,且桩顶应力大于桩间土应力;桩土应力比随着桩土差异沉降的增加先增加后减小,最终趋于稳定。结合修正的Terzaghi土拱理论提出了简化桩土应力比随桩土差异沉降变化曲线。现场试验分析结果有助于完善挤密螺纹桩复合地基设计理论,为工程实践提供一定的参考。

The pile and soil settlement and stress of the compacted threaded pile composite foundation of Huangtang Station of Xingquan Railway were monitored.The variation rules of pile and soil settlement and differential settlement under embankment load,and the relationship between pile-soil stress ratio and differential settlement were analyzed.Results show that pile settlement,soil settlement and differential settlement increase with the increase of embankment height and show a linear relationship.The soil stress at the top of pile and that between piles increases with the increase of embankment height,and the stress at the top of pile is larger than that between piles.With the increase of differential settlement,the pile-soil stress ratio increases at first,then decreases,and finally tends to be stable.Combined with the modified Terzaghi soil-arch theory,the simplified pile-soil stress ratio curve with pile-soil different settlement was proposed.The results of field test and analysis are helpful to improve the design theory of compacted threaded pile composite foundation and provide some references for engineering practice.