Research On Foamed Light Weight Soil Subgrade In BinLai Expressway Reconstruction And Expansion Project

With the rapid development of urbanization in China and the rise of new logistics industry,the links between different regions are more closely linked.Because of the advantages of fast,smooth,convenient and fast,the traffic volume of expressways increases year by year.Many important highways built early have entered into the state of saturation and overload operation.In China,the original expressway is implemented to improve the road transport capacity to meet the increasing demand for transportation.Firstly,the disease types and disease mechanism of expressway have been studied.In light of the domestic and foreign experts' measures for widening the differential settlement of subgrade,it is proposed to use foamed lightweight soil as widening roadbed filler.The basic characteristics,material design,preparation technology and engineering application of foamed lightweight soil were investigated at home and abroad,and detailed research outline was formulated.The formula of the traditional mixing ratio in the technical specification for the lightweight soil of cast-in-situ foam CECS249:2008 is revised.The moisture content of the soil is considered,and the content of the materials in the foam light soil is standardized.The foam light soil with different soil content was prepared,and through physical and mechanical properties test and durability test,it was proved that when the foam light soil was used as subgrade filler,the dosage of low liquid limit clay should be within 33%.Adhering to the concept of industrial waste recycling,we have developed foam lightweight soil mixed with red mud.When the same proportion(40%)of red mud and low liquid limit silty clay were mixed,the performance of the foam lightweight soil mixed with red mud was better than that of the light soil filled with soil.Therefore,when the foam light soil is used as the subgrade filling of the site engineering,the red mud can be considered as a substitute for some of the cement,and the cost of the engineering is saved as well as the utilization of industrial waste.Based on the site renovation project of binlai expressway,the interaction between new and old roadbed is studied by Plaxis.The variation trend of vertical and horizontal displacement of subgrade is widened,and the mechanism of widening the differential settlement mechanism of subgrade is explained,which proves the feasibility of foamed light soil as a widening subgrade filling.At the same time,through the analysis of the differential settlement of the density and modulus of the foam light soil with different subgrade filling,the optimum density of the foamed light soil widening subgrade is 8kN/m3 and the optimum elastic modulus 470MPa,and the proposed mix ratio of the foam light soil mixed with raw soil and red mud is put forward.Combined with the actual project in the field,the site test section was selected,and the construction plan of the foam lightweight soil roadbed widening was written.