Stability Analysis Of Airport Subgrade Under Groundwater Seepage

With the continuous progress of our society and the continuous development of the economy,China's aviation industry has also continued to develop at a high speed.The passenger and cargo transportation volume is increasing day by day,and the aircraft load is constantly increasing.The periodic changes of the tide,the tide changes in the coastal area,rainfall,groundwater extraction,etc.also have a certain impact on the airport roadbed.During the construction and operation of the airport subgrade,its stability is closely related to groundwater seepage and aircraft load.Therefore,it is of great significance to analyze the stability of the airport subgrade under the action of groundwater seepage and aircraft load.This article selects the following two aspects to study the stability of the airport subgrade.The first aspect is the subgrade settlement of the airport subgrade caused by the combined effect of aircraft load and groundwater,including the accumulation and dissipation of pore water pressure under the effect of aircraft load The long-term effect can be regarded as the complete dissipation of pore water pressure)and the deformation settlement caused by consolidation settlement and strain accumulation;the second aspect is the effect of groundwater level changes on the stability of airport subgrade.Aiming at the research contents of the above two aspects,the results achieved in this paper are as follows:(1)Abaqus was used to simulate the aircraft load,and the additional stress of the airport roadbed under the aircraft load was obtained,which laid the foundation for the next calculation of the pore water pressure accumulation-dissipation settlement and strain accumulation settlement caused by the aircraft load.(2)Using the GDS hollow cylindrical torsion-shear instrument,a circular stress path was selected to perform an undrained cyclic load test on soft clay near an airport,and the pore pressure accumulation data and strain accumulation of soil under different confining pressures and cyclic stress ratios were obtained Based on the data and analysis of the above data,the relevant parameters suitable for the empirical model were obtained on the basis of the pore pressure cumulative experience model and strain cumulative experience model established by the predecessors.By layering the soil of the airport subgrade,the average consolidation stress of different soil layers is obtained.Combined with the additional stress data of the subgrade soil under the load of the aircraft in the previous step,the cumulative pore water pressure of the different soil layers of the airport subgrade is calculated— Dissipative settlement and cumulative strain settlement,the above two settlements are layered and superimposed,and the pore water pressure accumulation-dissipative settlement,strain cumulative settlement and total settlement generated by the airport roadbed under the long-term action of aircraft load and groundwater are obtained.(3)A brief introduction to the theory of seepage consolidation,through the method of secondary development of subroutines,the self-defined change of groundwater level and the non-linear definition of permeability coefficient in the process of seepage consolidation of groundwater are realized.The groundwater changes uniformly and unevenly lays the foundation.(4)The groundwater seepage model of the airport subgrade is established,and the stability of the airport subgrade is simulated under the uniform and uneven changes of the groundwater level.The results show that: the decline of the groundwater level will cause the settlement of the airport subgrade.When the groundwater level remains unchanged,the airport The roadbed hardly settles,and the rise of the groundwater level restores the settlement;uneven changes in the groundwater level will cause uneven settlement of the airport roadbed,causing the concrete panel to produce tensile stress on the side with the higher water level,and the soil porosity is no longer It is evenly distributed and affects the stability of the airport roadbed.