An Investigation On Mechanical Property Of Expansive Soil Subgrade And Influence On Pavement Structure Performance

Expansive soil has many engineering properties including water-swelling,dry-shrinkage without water and various fracture pore.Therefore,it can cause subgrade expansive and settlement,imperil road traffic safety and decrease the durability.The existences of the expansive soil reduce the construction quality and usage capability of road seriously.Based on the damages of the road in high-tech zone,the characteristics of expansive soil were investigated through soil test.The effect of the expansive force generated by expansive soil on semi-rigid pavement structure was also studied.The subgrade treatment scheme was put forward and economic comparison was also conducted,the conclusions are as follows:1 The regularity of pavement deformation was obtained from field tests,by analyzing the behavior of pavement layers filling,the major cause of differential settlement in this section was proposed.2 Compaction test,free swell test,expansive force test of compacted soil was conducted,the expansive capacity and the range of expansive force of the soil sample was obtained from these tests.3 Based on the elastic layer system theory,BISAR program was employed to investigate the relationship between different expansive force,base modulus and mechanical and deformation characteristics of pavement layers,the failure mechanism of expansive soil subgrade and pavement structure was revealed.4 The treatment measure and scheme for expansive soil subgrade was put forward.Numerical calculations and analysis were performed to compare the mechanical and deformation characteristics of subgrade under different treatment conditions,economic analysis was performed to determine the optimal treatment scheme.In this study,the failure mechanism of expansive soil subgrade was revealed,the effect of expansive soil subgrade imposed on upper pavement structure was put into deep study,treatment scheme and measures for expansive soil subgrade were proposed,and economic analysis and comparison was used to determine the optimal treatment scheme.Current study provided theoretical and experimental basis for there in forcing treatment of expansive soil subgrade under water-rich condition.