Study On The Settlement Characteristics Of Loess Fill Subgrade In Gully Area Under Constraint Conditions

The fill subgrade of loess plateau gully area has a variety of forms of constraint.Fill subgrade deformation law under different constraints influence each are not identical,lead to different forms of differential settlement,and according to the traditional settlement calculation method often cannot accurately calculate the final settlement.In order to study the differential settlement mechanism of subgrade in different constraints and improve settlement calculation precision,this paper compared with deformation differencethe of the soil unit with or without lateral conditions,the differential settlement mechanism of filling subgrade and settlement calculation of subgrade lateral deformation considered was studied based on the national highway 307 Wu Bao to Sui De reconstruction project.First of all,according to analysis the indoor test results of unit soil,the deformation law of the unit specimens under different constraints.The influence of lateral deformation on the vertical deformation of soil unit specimens and the variation of poisson's ratio of soil in the subgrade were obtained by comparing the vertical deformation of the soil unit with the lateral limit condition.From the point of view of unit soil,the differential settlement mechanism of the filling subgrade is studied.Then,according to the results of monitoring and testing of loess subgrade,it is concluded that the different constraint conditions in loess fill subgrade settlement rule,proposed the loess roadbed settlement prediction equation with constraint conditions.The subsidence characteristics of loess filling subgrade settlement were obtained by comparing the difference settlement of loess filling subgrade.Finally,based on the relationship between lateral deformation and vertical deformation increment of soil unit specimens,the settlement calculation formula of soil lateral deformation is established,and the layered summation method is modified appropriately.And calculation have been carried out to verify the formula,the results show that the proposed considering the soil lateral deformation formula can better improve the calculation precision of layered summation method,under different constraints on the loess plateau gully area fill subgrade settlement calculation for reference.