Analysis Of Post-construction Uneven Settlement Of High Fill Runway In A Relocated Airport

In the process of high fill of an airport,the physical and mechanical properties of the original site and foundation soil are changed by excavation and filling.After artificial disturbance,the structure of the soil is damaged,the mechanical properties are quite different,the degree of compaction is difficult to control,the filling quality is uneven,and the excavation and filling surfaces of the airport runway interact,resulting in uneven settlement and excessive settlement of the high fill.In this paper,through on-site survey of the high fill project of relocated Ankang Airport,14 drilling holes were selected according to the site conditions,and on-site water level monitoring was carried out.Indoor geotechnical tests were carried out on the soil samples taken,the physical and mechanical properties of the foundation soil were monitored.Based on the results of field exploration and indoor geotechnical test,the filling quality of high fill is evaluated,and the backfill in the fill section is layered on the basis of settlement monitoring at the initial stage of construction completion,which provides the material parameters of each layer of backfill for later calculation.According to the layered situation,the settlement deformation and expansion deformation of high fill are calculated,and the deformation of high fill foundation of expansive soil is analyzed comprehensively.The main research results are as follows:(1)After the completion of construction,the groundwater level of the fill section is significantly higher than that of the original foundation before construction.However,the rise of the water level in the fill section may lead to the decrease of the soil strength of the high fill foundation and the failure of the site.Therefore,it is necessary to monitor the groundwater level continuously and take necessary engineering measures to reduce the groundwater level.(2)According to the physical and mechanical properties test of the actual dug soil and the remolded soil prepared according to the design compaction degree,it was found that the compaction degree of the backfill soil in the fill section did not meet the design requirements,there was a large difference between the actual water content and the optimal water content,and the compressibility of the backfill is obviously greater than the compressibility of the remolded soil,which is also the cause of uneven settlement after construction of high fill(3)Combined with the field settlement monitoring,according to the physical and mechanical properties of the soil samples of different depths obtained from the tests,the soil layers in the filling area are more reasonable layered(4)Using ABAQUS software and he layer wise summation method,the long-term final settlement value of high fill is calculated and analyzed,and compared with the field monitoring settlement value in the early stage of high fill construction,it is found that the settlement trend of fill is reduced,but the total settlement is still large,so further treatment of high fill is needed to avoid continuous settlement and uneven settlement(5)The expansion of expansive soil has little effect on the settlement of the middle part of high fill,but due to the cracks and expansibility of expansive soil,it is necessary to strengthen the slope protection and maintenance.