Research on Compaction and Load Strength of Expansive Soil Subgrade

Relying on the project construction of the second-class road from Chongzuo to Shangsi in Guangxi Province,on the basis of lots of data gathered from the combination of lab.tests and field constructing test section,the characters and relationship between degree of compaction,compaction effect,water content and CBR of weak expansive soil when is filled in subgrade are analyzed.For the same kind of expansive soil,the more compaction effect is,the bigger maximum dry density is,and the smaller optimum water content is.For different kind of expansive soils,when at the same compaction effect,the smaller the expansibility is,the bigger CBR is.As well as for the same kind of expansive soil,the more compaction effect is,the bigger CBR is,but the water content correspond to maximum CBR is equivalent approximately.On the project area,nature water content of most weak expansive soil is about 15% to 18%,that is correspond to water content when weak expansive soil's CBR gets to maximum,furthermore,although span of water content is more 4% to 7% than optimum water content of normal compaction,as long as it doesn't overstep the upper limit,it's easy to meet degree of compaction with more compaction effect when at field subgrade construction.