摘要
为了揭示水泥土搅拌桩复合地基的固结特性,进行了端承型水泥土搅拌桩复合地基和悬浮型水泥土搅拌桩复合地基加固软土地基的室内模型试验。通过监测荷载作用下复合地基桩顶和桩间土沉降、桩顶和桩间土应力及软土中不同位置处的超静孔隙水压力,分析了2种复合地基的桩土应力比、桩体荷载分担比、超静孔隙水压力消散等变化规律的差异性。研究结果表明:端承型搅拌桩较悬浮型搅拌桩可以明显减少复合地基的总沉降量与工后沉降;由于桩土刚度差异导致的桩土差异沉降引起了桩间土承担的荷载向桩体转移,桩间土承担的附加应力减少,桩土应力比增大,桩体荷载分担比增加,进而加速搅拌桩复合地基的固结;端承型水泥土搅拌桩复合地基较悬浮型水泥土搅拌桩复合地基的桩土差异沉降大,桩间土荷载转移现象更加显著,固结速率也更快;水泥土桩在复合地基中的排水通道作用并不显著,但因其模量较桩间土大,因此可以在一定程度上加速复合地基固结。
To find out consolidation behavior of soft clay improved by deep mixing columns, two laboratory model tests were carried out to measure the responses of soft grounds improved by end bearing deep mixing columns and floating deep mixing columns respectively. The settlements of column and surrounding soil, the stresses of column top and surrounding soil and the excess pore water pressures at different locations in the soft clay were measured under load. The difference between two kinds of composite grounds was analyzed in terms of column-soil stress ratio, loading sharing ratio, and the dissipation of excess pore water pressure. The results show that the composite ground improved by end bearing deep mixing columns is more effective in reducing the total settlement and the settlement after construction than that improved by floating deep mixing columns. Differential settlement is developed between the deep mixing column and the surrounding soil due to the stiffness difference between column and surrounding soil. Thus, more and more loading is transferred progressively from the surrounding soil to the deep mixing column, the additional stress on surrounding soil is reduced, the column soil stress ratio is increased and the loading sharing ratio of column is increased. Consequently, the degree of consolidation of surrounding soil is enhanced. This enhancement effect in the composite ground improved by end bearing deep mixing columns is more obvious that that by floating deep mixing columns. In addition, the drainage effect of deep mixing column in composite ground is not obvious, but its modulus is bigger than surrounding soil. To some extent, the deep mixing column can accelerate the consolidation of composite ground.
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2014年第12期1-9,共9页
China Journal of Highway and Transport
基金
"十二五"国家科技支撑计划项目(2012BAJ01B02)
中央高校基本科研业务费专项资金项目(2242014R30020)
中交第一公路工程局有限公司自主项目
江苏省高校"青蓝工程"优秀青年骨干教师计划项目
关键词
道路工程
搅拌桩
模型试验
固结
荷载转移
road engineering
deep mixing column
model test
consolidation
loading transfer
