Study On The Treatment Methods Of Land Fill And The Reinforcement Of Subgrade In Highway Engineering

When the road route inevitably passes through the urban landfill,and the mixed filling is highly compressible;the composition of the filling is complicated and the structure is soft,which seriously affects the construction of the highway project.Therefore,the reinforcement of the landfill site is an important measure to improve the strength and bearing capacity of the subgrade.In this paper,the research is based on the project as “Fuyao Highway of Red Tourism”,which focuses on the treatment of landfill and the reinforcement of the subgrade.In this paper,the research was based on the project as “Fuyao Highway of Red Tourism”.The road route passes through multiple landfills.How to deal with the roadbed of the miscellaneous filling area with the landfill`s basic characteristics,economical and on-site construction conditions of the mixed filling is very important.In view of the treatment of landfill miscellaneous fill and the problem of roadbed reinforcement,the following research is carried out:The research has detected the basic physical and mechanical properties of the landfill by analyzing the physical composition,testing the moisture content,testing organic matter content and testing particle sieve,specific gravity and compressibility.According to the difference and particularity of the landfill foundation,the research has studied the reinforcement mechanism,the scope of reinforcement and the reinforcement process,and compared the commonly used methods of mixed soil and subgrade reinforcement.What`s more,the method of combining “cured material treatment of miscellaneous fill and reinforcement of subgrade” is firstly proposed in the paper to solve the problems of high compressibility and low bearing capacity.The core indicator of the reinforcement of the subgrade is to enhance its strength and carrying capacity.In the research,the lime,the cement and the curing agent were taken as the curing materials for the treatment of the mixed filling.According to the mechanical properties test and economic comparison,the most suitable set of curing materials for the field treatment of the mixed filling was selected.Through the comparison of the subgrade reinforcement and the mixed fill treatment method,the research has selected the method of combining “curing agent-dynamic compaction” to strengthen the miscellaneous filling area.In order to detect the reinforcement effect of the dynamic compaction method on the mixed foundation,the soil-based elastic modulus and bearing capacity are used as the evaluation index of the subgrade reinforcement.After the reinforcement,the test results show that the strength and load-carrying capacity of the subgrade are obviously improved with only one time compaction;the modulus value after reinforcement at 18 points are more than 70MPa;the bearing capacity of the foundation is more than 235 kPa,of which 13 points are slammed in advance to end the procedure.Besides that,after curing,the organic content of the soil is <5%,and the compressibility is also significantly improved to meet the engineering standards.The relational equation of the comprehensive settlement and the elastic modulus is proposed for the first time,which is an indicator to reflect the change of the subgrade strenth by the change in the amount of settlement.After the curing and dynamic compaction,the research has found the relational equation between the cumulative subsidence x(cm)and the rebound modulus y(MPa): y = 0.5469 x + 41.542,R2 = 0.9792,which plays a guiding role in the reinforcement of the remaining miscellaneous filling areas.Through the soil test,detecting the changes of organic matter content,void ratio and compression coefficient parameters of the soil before and after reinforcement respectively,then comparing the reinforcement effect of the “curing agent-dynamic compaction” scheme with the traditional reinforcement method.The results show that the “curing agent-dynamic compaction” method not only reduces the organic content in the soil,but also effectively increases the compactness of the soil,enhances the strength and load carrying capacity of the subgrade,simplifies the construction procedure.