Experimental Study On Base Treatment Techniques And Reinforcement Effect Of Highway Subgrade In Hetao Irrigation Area

The Hetao area is an important irrigation area with a large number of cultivated land.In the season of irrigation,the groundwater level will increase greatly.In this area,the settlement control problem caused by the main existence of groundwater and soft ground in the highway,the surface water problem of spring ploughing and autumn irrigation and flood irrigation,and the instability of the subgrade uneven settlement are also existed.The treatment of bad foundation in Hetao irrigation area is usually strengthened by the method of drainage consolidation and composite foundation,but the previous engineering practice shows that some conventional foundation reinforcement technology(pile composite foundation)has high cost and poor economy,and the hard shell layer of the ground base is fully utilized in some projects without destroying the hard shell layer.On the basis of filling the applicable road materials and reinforcing the roadbed,good settlement control after construction is achieved.The project is derived from the Inner Mongolia transportation and transportation department.Based on the Beijing new high speed Shaanxi dam connection line project,it is carried out jointly by the Inner Mongolia Traffic Design Institute and the Shandong Jiaotong University.The research on the treatment technology of the poor subgrade base treatment in the Hetao irrigation area along the line can provide reference for the design and construction of similar projects in the future.It has important guiding significance for the construction of Hetao area.Firstly this project carried out the analysis and Research on the treatment plan of the bad roadbed in Hetao area of Inner Mongolia.After referring to a large number of related literature,we summarized the physical and mechanical properties and engineering characteristics of silt in Hetao silty area.To investigate the project along the irrigation area bad foundation sections,put forward five kinds of substrate solution studies.They are gravel filling,single geocell and sand cushion,double geocell joint single-layer sand cushion,geogrid with sand cushion,double layer geogrid combined with sand cushion studies.In addition,using PLAXIS software to establish the finite element model of subgrade,the thickness of the cushion structure parameters and cohesion,internal friction angle,elastic modulus of three kinds of material parameters and other factors on subgrade settlement and stability,respectively for five schemes of the subgrade were analyzed base treatment effect,feasibility of the five schemes bad foundation treatment section of subgrade is theoretically verified.Finally,in the test section buried soil pressure box,pore water pressure gauge,layered settlement meter,flexible displacement sensor and the settlement plate to obtain the test data,replacement,single geocell combined with sand cushion,double geocell joint single-layer sand cushion,geogrid with sand cushion,double soil the grille combined with sand cushion five kinds of substrate treatment scheme of subgrade stress and deformation distribution and variation of comparative analysis of gravel,selected the best basal treatment scheme of settlement control.The measured results show that the settlement of the Subgrade after five schemes can meet the requirements of the relevant specifications,especially the strengthening effect of the base treatment section of the lithotripsy cushion.