Study On The Deformation Law Of Composite Foundation With Lime-soil Pile Incollapsible Loess Area

China has the loess of thewidest distribution,the biggest thicknessand the bestintegrality in the world.But the structureof loess is loose,thestrength is insufficient and collapse deformation happens afterimmersion,or even collapse.China's economic develops so rapidly so it is inevitableto build a project in the vast loess areas.The strength of loess itselt is not enough to meet the demand of engineering construction.Therefore ithas becomes a primary task of the foundation treatment in the loess area to eliminate the collapsible deformation of loess and improve the strength of the loess.Lime soil pile composite foundation is a good way.In addition,the cost of lime and soil is cheap and theconstruction of lime soil pile is convenient.The lime soil pile composite foundation is widely used in loess foundation treatment,its huge social and economic benefits are obvious.Thelawsofcollapsedeformation and compressive deformationare obtained from two aspects of theory and experiment.(1)thewet trappinglaw:The collapsibility of lime soil pile is influenced bypile diameter,pile spacing and lime-soil ratio,etc.pile spacing and lime-soil ratio ranks 1st,pile diameter is in bottom place.Therefore,asmaller pile spacing,a larger soil ratio can achieve the same effect.Pile diamete is limited at the elimination effect of the Loess collapsible.The static load test of large-area soaking shows thattreat foundation or not has a great influence on the collapse deformation of loess foundation.For those loess foundations with smaller processing width and packing forprime soil,the collapse deformation is smaller than those without foundation settlement.That shows the eliminating dampness effect of prime soil is limited.Besides,pile spacing and processing width have a obvious effect on eliminating dampness.Composite foundation with lime-soil ratio 3:7 has a small collapse deformation.That shows lime-soil ratio 3:7 is better than prime soil for eliminating dampness.In 2?4m layer,the collapsible deformation showed the similar rules to2m layer,and is smaller collapsible deformation than 2m layer.This is because 2m layer is the main part of the action of external load,includingvertical and lateral extrusion deformation,butthe lateral deformation of 2?4m layer is very weak.No treatment of foundationinthis layer,the collapse deformation of the ground is close,the deformation of the following sections of the 5m is very large,this part of the soil has a self weight collapse deformation.In short,the foundation treatment can significantly reduce the collapsibility,and the pile distance,width and the ratio of lime treatment can reduce the collapsible effectsignificantly.Plain soil can also reduce the collapsibility,but the effect is limited.(2)the compression deformation law:Based on Qinghai Chuankou-De hejia road project,combined with a large amount of documentsof Qinghai area,compression deformation rules of lime soil pile is found related to many factors.This paper discusses the influence of lime soil ratio,pile spacing and pile diameter on settlement deformation and bearing capacity.The static load experiment is carried out by selecting different pile diameter,pile spacing and lime-soil ratio.The result shows that lime-soil pile settlement deformation and bearing capacity is related to pile spacing and loess-soil ratio,the correlation ofpile diameter is small.The influence of pile spacing is the greatest,followed by lime soil ratio.Therefore,in engineering to achieve the same treatment effect,the first consideration is the design of pile spacing on the effect of compacting effect,followed by lime soil ratio,the lastis pile diameter.