Experimental Study On Expansive Behaviors Of Quicklime And Its Application In Foundation Treatment

Quicklime pile composite ground is a simple,economical and effective method for treating ground,which has been widely used in engineering practices,especially for the collapsible loess field,quicklime pile is one of main ground treatment methods to eliminate the collapsibility of loess,increase the bearing capacity and improve the behavior of composite ground,its economy and reliability has been generally accepted in engineering circles.With the expansion of the city construction scale,especially in most of the northern city,the construction land mostly arrived at the river levelⅢorⅣterrace,most of these landforms are the deep(generally deeper than 30 m) loess or collapsible loess.It is more important to study the ground reinforcement and deviation rectification technology in these sites.In recent years,rectifying and reinforcement technology of the expansion of quicklime is widely used for incline buildings in northwest and north China area,better environmental,social and economic benefits are brought by quicklime pile.In addition,quicklime pile has also been widely used in highway projects in the loess ground.To study the expansive behaviors of quicklime,the quicklime and the mixture of quicklime and cement are took as the test specimen,in the test these factors influencing quicklime expansion are considered which includes grinding rate, mixture ratio and pressure and so on.The quicklime expansive rule is obtained from these test results,no matter how these influencing factors change,the quicklime volume expansivityηand pressure p always appear following relationship:η=Aln p+B,The formula can be took as a foundation in the caculation of expansive quantity and provide more accurate design parameter for engineering.The anthor employs elastic theory to solve the coupling problem,and for the first time obtains the mathmatic relation between pile hole inwall displacementμ_r and quicklime expansion pressure p:u_r=(1+ n)d~2p/(4Er).In this paper the anthors uses qicklime expansion characteristics resulting from laboratory test to explore the ground-compaction effect that quicklime exerts on ground,shows the relationship between quicklime volume expansion coefficient 77 and ground depth z:η=Aln(K_orz)+B,This calculation formule produces more accurate and reliable result than before.Through a calculation example it is indicated that the effection depth of the quicklime exerts on ground deeper than 13m is insignificant.This conclusion provides theory evidence for the appropriate use of this method in ground treatment.