水泥粉煤灰搅拌桩复合地基沉降特性研究

Study of the Fly-ash Cement Mixing Pile Composite Foundation Settlement Characteristics

针对渭蒲高速公路饱和黄土地基用水泥粉煤灰搅拌桩加固路段,采用埋设沉降杯法进行了长期的现场监测。通过分析监测数据,得出了复合地基的沉降量、沉降速率随上部荷载和时间的变化趋势。同时结合实体工程中复合地基的各项参数,对其沉降量进行了理论计算和数值模拟。对比三种复合地基沉降量的分析方法得出:柔性荷载作用下复合地基的理论计算因受桩体刺入下卧层长度、桩侧摩阻力等各种不确定因素的影响,不同理论计算方法的结果差异较大,实际意义不大;现场监测和数值模拟结果具有相似性,但是忽略了实际工程中次固结沉降对饱和黄土地基沉降的影响,故数值分析值偏小;针对饱和黄土的特殊工程性质,可将现场监测的结果与数值分析的规律结合起来,对复合地基的最终沉降进行预测。

Aiming at the section which was strengthened by fly-ash cement mixing pile of saturated loess foundation in Weinan-Pucheng expressway,a buried settlement cup method has been adopted in field monitoring. According to the monitoring data such thing like foundation subsidence of composite foundation and the trend of settlement rate with upper load and time has been got. Then theoretical calculation and numerical simulation has been combined to study on the foundation subsidence of composite foundation in entitative engineering with its parameters. The results show that the results was quite different in upper three theoretical calculation methods,because of it was affected by all kinds of uncertainty factors such as pile length which Piercing the underlying layer and Pile shaft resistance. And its actual significance was not very. The results of field monitoring closer to that of numerical simulation,but the value of numerical simulation was small for something like saturated loess foundation affected by secondary consolidation settlement has been neglected. Based on the special engineering property of saturated loess,the final settlement of composite foundation can be forecasted by which combined with the result of field monitoring and the discipline of numerical simulation.