水泥粉煤灰搅拌桩复合地基的离心模型试验及现场实测效果研究

在水泥桩体中掺入一定量的粉煤灰不仅可以节约资源,还可以增强桩体在酸性地基中的抗腐蚀性能。为了研究水泥粉煤灰搅拌桩处治饱和黄土地基的适用性,以蒲渭高速公路为工程依托,以水泥与粉煤灰不同重量比组成的固化剂及其不同掺入比配制的试件进行的无侧限抗压强度试验、直剪试验和固结压缩试验为基础,选择最佳配比后进行水泥粉煤灰搅拌桩的离心模型试验,并与现场实测结果相对比。结果表明:当水泥与粉煤灰的重量比不小于2∶1时,粉煤灰的添加对试件的抗剪强度影响不大;固化剂掺入比达到15%以后,水泥粉煤灰土与水泥土试件的强度相差值减小;离心模型试验所得工后沉降量小于0.3m;现场实测工后沉降量和桩体强度均符合设计要求。水泥粉煤灰搅拌桩处理饱和黄土地基是经济可靠的。

Comparative analysis on results from centrifuge model test and field test for cement-fly ash mixing piles

The cement pile mixed with a certain amount of fly ash not only saves the resources,but also can enhance corrosion resistance of the pile in the acidic foundation.In order to study on the applicability of the cement-fly ash piles for the treatment of the saturated loess foundation,based on the tests of unconfined compression strength,direct shear and compression consolidation for the curing agent composed by different weight ratio of cement and fly ash and different mixing ratio of curing agent in the Pu-Wei expressway construction,the testing results from centrifuge model tests and field tests for the cement-fly ash mixing piles are analyzed after the optimum ratio is selected.The results show that when the weight ratio of cement and fly ash is not less than 2∶1,the addition of fly ash has the little effect on the shear strength of specimens;after the mixing proportion of curing agent reach 15%,the difference between the strength values of the cement-fly ash soil and the cement soil reduces;the settlement from centrifuge model tests is less than 0.3m;the settlement and strength of the piles meet the design requirements.The treatment of saturated loess foundation with cement-fly ash mixing piles is economic and reliable.