Coupling Analysis Of Seepage Field And Stress Field In The Second Runway Of Lhasa Gongga Airport

With the rapid development of my country’s economy,the airport,as an important facility of my country’s comprehensive transportation system,has entered a stage of rapid development.The second runway of Lhasa Gongga Airport is to be filled in the floodplain area.The surface water system and groundwater of the site are developed.There are a large number of braided rivers near the site,the groundwater level is high,the foundation has strong permeability,and the liquefied soil has a wide distribution range.The problem is extremely prominent.To provide a basis for later engineering construction,this article conducts research on the height of groundwater level and foundation settlement of the second runway under the action of seepage field and stress field.First of all,starting from the geological survey of the site,understanding the relationship between groundwater replenishment and drainage in the entire site,and dividing the site into hydrogeological units.Secondly,considering the establishment of a groundwater numerical simulation model,it is necessary to know the hydrogeological parameters.Starting from the field permeability test,the screening test,water seepage test and pumping test were done respectively.The screening test adopts on-site large-scale particle analysis test to analyze the gradation of sand and gravel soil,naming sand,gravel soil,etc.,and analyze their particle composition and gradation;the single-loop method is used in the seepage test to understand the shallow surface permeability coefficient of the site(The Quaternary artificial fill,Quaternary alluvial silt,silty fine sand,Quaternary alluvial gravel);single-hole and multi-hole pumping are used in the pumping test to understand the permeability coefficient of the pebble layer in the site.Then,on the basis of the above,modflow software is used to establish a three-dimensional numerical simulation model of groundwater,and steady-state flow and transient flow are used to analyze the changes in seepage field in the dry season,wet season and once-in-a-hundred-year flood conditions.Based on the hydraulic slope obtained by the simulation analysis,combined with the results of the stratum screening of the field,it can be judged whether the field will see seepage deformation.Finally,according to the calculated seepage field,Geostudio software is used to couple the stress field to analyze the foundation settlement of the site under different working conditions.According to the analysis results,it can be understood whether the groundwater problem in this area will affect the construction of the airport runway.