Study On Structural Optimization Of Rigid Pavement Based On Improving Service Life

In recent years,civil aviation industry has developed rapidly.With the continuous operation of large aircraft and the increase of air traffic volume year by year,runways are also assuming more and more important responsibilities.The runway will inevitably be impacted and damaged when it is used.Compared with the design service life,there are often problems such as structural damage and service performance degradation before withdrawal,and even some airport pavement cracks,voids and even broken slabs after several years of construction This not only affect the way the normal use and safe operation of aircraft,but also seriously shorten the service life of pavement.Therefore,it is necessary to study the dynamic response law of the airfield pavement under the actual state,analyze the factors affecting the pavement life and put forward the corresponding methods to improve the life.Previous studies have shown that the required dynamic response information can be obtained from the corresponding monitoring equipment in field tests.However,the experiment is time-consuming and requires a large amount of manpower and material resources,so it is difficult to use this method in practical conditions.Therefore,the relevant finite element calculation is carried out by computer simulation with reference to the research methods of many scholars.In this paper,with the help of the powerful computing function of the national supercomputer Tianjin Center,combined with the relevant theoretical analysis,the aircraft taxiing and fixed-point impact model under the excitation of pavement roughness is established,and a large number of finite element calculations are carried out.The influence of rigid pavement structure parameters on dynamic response is analyzed,which provides a theoretical reference for improving rigid pavement life from time domain and frequency domain.The main research contents and achievements are as follows:1.Different roughness simulation methods were compared and ANSYS simulation was used to generate the roughness values under different IRI values of the pavement level.A4-DOF aircraft model was obtained through analysis and simplification,and the equations of coupled vibration system were established and solved.2.According to the actual conditions,the rigid pavement structure model of the airport was established by using ANSYS software.Combined with the relevant mechanical analysis,the random maneuver load generated by the roughness of the pavement was loaded onto the pavement,and the dynamic response of the pavement caused by the maneuver load was obtained by simulation.The vibration response of the pavement under different working conditions is analyzed by using the transient dynamics principle.3.By comparing and analyzing a large number of finite element calculation data,the dynamic displacement change law of pavement and surface layer under aircraft dynamic load was obtained and its influencing factors were analyzed.It is found that the modulus of soil foundation has the greatest influence on the reduction of dynamic displacement.When the modulus of soil foundation is more than 100 MPa,the influence on dynamic displacement decreases obviously.The modulus of surface layer and the thickness of surface layer have some influence on the reduction of dynamic displacement,and the reasonable reference values are given according to the calculation respectively.The modulus and thickness of the base have little effect on the dynamic displacement.4.From the perspective of frequency domain,using Matlab software,the frequency spectrum analysis of aircraft random load is firstly carried out to get the load dominant frequency,and the influence of speed on the dominant frequency is studied.Then,transient impact is applied to the model.According to the extracted acceleration signals,spectrum analysis is carried out to obtain the fundamental frequency of the path surface.The influence of the value of the path structure on the fundamental frequency is analyzed.It is found that the soil modulus has the greatest effect on the fundamental frequency,and the fundamental frequency increases with the increase of the soil modulus.The thickness of the surface layer and the base layer also has a certain effect and has an approximate linear relationship.