广西红土击实特性的影响因素及机理分析

The Influence Factors of Compaction Characteristics and Mechanism Analysis of Laterite in Guangxi

红土是由原岩在湿热气候条件下经过红土化作用形成的具有高含水率、大孔隙比、较高强度和较低压缩性的一种特殊土。由于其特殊的工程地质性质形成了红土具有较大工后沉降的特性。目前,工程中普遍采用强夯的地基处理方法对其进行处理,对于夯后红土地基变形则通过现场监测结合室内试验的方法进行研究。笔者通过室内击实试验和击实后红土的高压固结试验,深入探讨影响红土击实效果和击实后压实性的主要因素,并对各影响因素进行影响机理分析。试验结果表明:红土的击实效果与击实功成正比,与黏粒质量分数、塑性指数、游离氧化铁质量分数成反比;击实后红土的压缩模量受含水率、干密度及饱和度等因素的综合影响,并且各因素的影响程度不尽相同;当含水率大于18%时,土体处于近饱和状态,含水率与干密度已经不能反映饱和红土的压实性了,即在实际的强夯工程上这种土的含水率不宜大于18%,否则会产生较大的工后沉降。

Laterite is a kind of special soil which was formed by the laterization in the condition of hot and humid climate with the characteristics of high moisture content,large void ratio,higher strength and lower compressibility. As its special engineering geological properties there will be a larger settlement after construction on the foundation of red soil.Nowadays,the dynamic compaction as a method of ground treatment is widely applied and the deformation of laterite foundation after construction is always studied by field monitoring combined with laboratory test.The main factors which affect the compaction effect and the compaction characteristics of the laterite after compaction aredeeply discussed on the base of the compaction test and consolidation test in the laboratory.And the mechanism analysis of factors are made.The experimental results show that the compaction effect has related with the content of clay,the plastic index,the free iron oxide and the compaction effort.The more content of clay,the higher plastic index and the more content of the free iron oxide would lead the worse compaction effect.The compaction effect is also in proportion to the compaction effort.The compression modulus of laterite after compaction is affected differently by the factors such as moisture content,dry density and degree of saturation.When the moisture content of the laterite is greater than 18% and the degree of saturation is close to 100%.The moisture content and dry density can’t reflect the compaction characteristics.Hence,in practical engineering the moisture content of the laterite shuold not be greater than 18% to avoid the larger settlement.