Experimental Study On The Characteristics Of Expansion Soil Weathering Sand Modified

It often needs to improve the expansive soil when we construct highway with it.Atpresent,we use inorganic binder such as lime, fly ash and cement to improve expansive soilin engineering practice.Using inorganic binder modified expansive soil,while it is possibleto improve the engineering properties of expansive soil,but difficult in construction control,environmental pollution and the high cost of shortcomings.In this paper,based on thecharacteristics of Weathered sand widely distributed in Yichang city,relying on the firstgrade highway rebuilding project from Xiao xita to Ya queling,we studyed on physicalproperties,swelling and shrinkage properties and mechanical strength characteristics ofimproved expansive soil with weathered sand in laboratory.We find that differentproportion of expansive soil modified with different sand weathered sand ratio,and theinfluence law of sand ratio on improved soil characteristics,at the same time,the stabilitycalculation of subgrade slope which filling with weathered sand soil is conducted.The mainresearch work of this paper can be summarized as follow:Study on physical properties,swelling and shrinkage properties and mechanicalstrength characteristics of improved expansive soil with weathered sand,based on theresearch of physical properties,the incorporation of weathered sand can improve the watercharacteristics,compaction characteristics,and over consolidation of expansive soil,theimproving effect increases at first and then gradually flatten with the increase of sandproportion;the rasearch of swelling and shrinkage properties shows,the incorporation ofweathered sand can effectively inhibit the expansion,and improve the shainkagecharacteristics of expansive soils,shrinkage index of improved expansive soil decreasedgradually with the increase of sand ratio,free swelling ratio showed a linear change withthe change of sand ratio;when the sand ratio is greater than20%,the swell shrink totalrateof improved expansive soil is less than0.7%,the free expansion rate is less than40%,whichmeet requirements of the relevant technical;The research results on mechanical strengthindex show that,the incorporation of weathered sand can improve the strength of expansivesoil,achieve the subgrade filling requirements,the incorporation of weathered sand has littleeffect on the expansion of the internal friction angle of soil,the viscosity of expansive soilcohesion increases with larger influence; sandratio,with out first increases the compressivestrength and rebound modulus side limitdecreases after improved soil,when the sand ratiois10%,at this time nomaximum compressive strength and elastic modulus of lateral confinement;with the increasing sand ratio,the improvement of expansive soil CBR valueincreased gradually,and the growth trend of faster and slower.Comprehensive technical analysis of economic indicators and determine the mix ofconstruction,the test road paving and field test monitoring have been done at the sametime.Considering the technical and economic indicators,determined the construction ofweathered sand mix is20%.After three consecutive months of observation Settlement onthe first grade highway from Xiao xita to Ya quelling which the improved expansive soilused,observations showed that the monthly average settlement rate2.1mm,which meet thedesign requirements of less than3mm,The subgrade settlement of the test road tends to bestable from the third week,the feasibility of expansive improved by weathered sand isverified in practical engineering.