Analysis And Research On The Performance Of Subgrade Filling In The Condition Of Freezing And Thawing Cycle

The marine sedimentary soft clay layer widely distributes in the coastal areas of Tianjin,and the marine sedimentary soft clay was characterized as high porosity,high pressure,high water content,low permeability,low bearing capacity,etc.Because Tianjin is located in the seasonal frozen and higher water table area,the road structure is subject to be thawed and frozen.Freezing and thawing may greatly cause the destabilization of subgrade filler,and even seriously affect the life and quality of road.Therefore,it is very important to make the marine sedimentary soft clay a good roadbed filler by improving its properties,which also has momentous practical significance for the construction of engineering economy in Tianjin area.In the current study,basing on the characteristics of subgrade defects in Tianjin area,we improved the marine sedimentary soft clay to be a better subgrade filler by mixing lime into the clay in the roadbed.By combination with the project of Jinbei Road in Tianjin Aviation Industry Zone,we first analyzed the physical and mechanical properties of marine sedimentary soft clay and tested the improving methods of subgrade filler in our lab,We carried out different modification with adding series dosage of lime into the marine sedimentary soft clay to explore the variation of properties of the mixtures before and after freezing and thawing under wet and dry condition by coMParing with appropriate indicators of the prime clay.The Mechanical properties of modified clay can meet the requirements of road subgrade filler after mixed with lime.The temperature and humidity sensors were buried into the structure of subgrade filler of the section of Jinbei Road’s project,then we found that first 40 cm underneath of the subgrade surface is a very important parameter for choosing the subgrade filler that can reduce the subgrade’s frost heave value and force.Based on the laboratory experimemts results,regularity of the stress distribution and deformation of lime modified soil subgrade in freezing and thawing were analyzed by finite element theory and ANSYS software.It indicated the lime can reduce the occurrence of the phenomenon of frost heave,and reduce the subgrade uneven settlement.