Study On The Stability Of The High Fill Slope Of An Airport In A Mountainous Area In Southwest China

The terrain and geomorphological conditions in the southwest region are complex and the terrain is undulating,and the construction of a mountain airport will inevitably form a large-area,high-fill slope that spans multiple geological units.Therefore,the stability of the high-fill slope of the newly built mountain airport has always been the southwest airport Research focus of the project.In this paper,through field investigation of the proposed airport and collect field engineering geological survey and special survey data in the study area,and analyzes the environmental geological conditions of the research area in combination with the actual conditions of the project.The slope stability will be analyzed and evaluated from aspects: the natural unstable factors of slope,the deformation of fill body and the stability of high-fill structure.(1)According to the geological conditions of the natural slopes in the study area and the physical and mechanical properties of the rock and soil,the deformation and failure forms of the natural slopes are analyzed through geological analysis.Using the Flac-3D software,the stress distribution and deformation of natural slopes under natural conditions and rainfall were analyzed and calculated.The Mohr-Coulomb yield criterion was used to circle the plastic failure area of the slope.The analysis shows that the natural slope is stable under both natural conditions and rainfall conditions;the impact of the bedding layr(G1)squeeze zone on the natural slope is limited,and no deep slip surface is formed.(2)Using the software Geo-studio / Sigma module,taking the typical profile of the high fill slope in the study area as the basis of the geological model,and in accordance with the finite element modeling principles,establish a finite element calculation model to analyze the weight of the fill body Deformation failure mode of slope under action.The analysis results show that the fill slope will form a shear stress concentration at the foot of the slope and where the thickness of the fill body is the largest,resulting in settlement deformation accompanied by a certain displacement deformation outside the slope;the shear strain mainly occurs in the fill body and the Quaternary cover surface of the layer or the quaternary covering layer may form a slip surface that penetrates through.(3)By applying the software Geo-studio / Slope module to the two-dimensional typical profile under different working conditions,the limit equilibrium principle is applied,and multiple methods are used for calculation and comparison to find the most dangerous sliding surface.Combined with the analysis of Flac-3D software,the stress distribution of different parts of the high fill slope and the plastic failure zone of the fill body and the G1 compression zone were circled.The comprehensive calculation results of the 2D and 3D of the high fill slope show that the high fill slope is basically stable in the natural state,and damage will occur under rainfall and earthquake conditions.The deformation and instability of the strong weathering layer occurred;but the compression zone was basically under shear,but its plastic zone was not penetrated,so it was difficult for the overall slope deformation and instability to occur.(4)Based on the results of the above-mentioned slope stability evaluation,specific prevention measures are proposed for the high-fill slope.