| In recent years,against the background of rapid economic development,greenhouse gases have become a pressing environmental issue due to the large amount of carbon emissions from vehicle exhaust.In this context,the government has accelerated the construction of subways to achieve low-carbon travel and thus achieve "carbon neutrality" and "carbon peaking".Air travel has the advantage of being fast,efficient,and effective in saving time and reducing carbon emissions,so connecting the subway and the airport project becomes an effective measure to optimize urban transportation and form a travel mode that connects transportation modes.In this thesis,the impact of aircraft slip-running on the stability of the tunnel structure under the airport runway is studied as an object of research,and the main research contents and conclusions are as follows:(1)The Mohr-Coulomb principal structure model is used for the soil material,and the linear elastic principal structure model is used for the simulation of the surface and base layers,and the mechanical model of the synergistic deformation of the airport runway-soil-tunnel structure is established.(2)A "five-point contact" type aircraft six-degree-of-freedom dynamics model and mechanical equilibrium equations were established considering the lift effect,and the transformation of the aircraft wheel print was realized.The Dload subroutine was developed in Fortran language to simulate the sinusoidal excitation load of the airplane,and it was applied on the finite element model.(3)The structural model of airport runway-soil-tunnel structure synergistic deformation was studied,focusing on the influence of factors such as tunnel section form,burial depth,lining material,lining thickness and runway type on structural safety.The results show that: as the burial depth of tunnel structure increases,the influence of ground stress on the stability of tunnel structure increases,the impact effect of aircraft load is relatively small,and the structure is attenuated by the interference of aircraft load;the stability of tunnel structure with circular cross-section is the best;the higher the concrete strength of lining structure,the better the stability;the deformation of tunnel structure gradually decreases with the increase of lining thickness,and it is closely related to the position of aircraft Closely related;flexible road surface has a good attenuation effect on the diffusion of forces,the shear stresses on the upper and lower arches of the tunnel structure are different depending on the road surface material,and the deformation of the arches under shear stress is more violent than other parts.(4)Taking an airport project as an example,the mechanical response of the subducted tunnel structure of the airport runway under the action of aircraft load is analyzed.The results show that: the mechanical response of the tunnel structure varies greatly with the change of aircraft load application position;the fluctuation trend of aircraft dynamic load equation will have a significant impact on the structure;the top and bottom plates of the tunnel structure under the runway are in tension under the aircraft load,which are relatively weak parts and need to be considered when designing;the mechanical response index of the structure will change abruptly at the intersection of the airport road surface and the tunnel structure due to the material The mechanical response index of the structure at the intersection of the tunnel structure and the airport roadway will change abruptly due to the difference in material properties,and the degree of aircraft load disturbance decreases gradually with the increase in soil depth,so the impact of aircraft load should be considered at the joint of the tunnel roadway layers.The results of the study can provide theoretical support for the airport construction and can be used as a reference for the study of the safety and stability of the airport runway substructure. |
