# Study of the Dynamic Response of a Rigid Runway with Different Void States during Aircraft Taxing
## 1 Introduction  
China is one of the countries with the highest number of airports, and civil transport airports completed 907.483 million passengers and 9.777 million aircraft movements in 2021 [1]. While the number and frequency of large aircraft takeoffs and landings continue to rise, the dynamic interaction between aircraft and runways has become more obvious. The void of the cement concrete slab on the runway surface is an issue that easily occurs when the rigid pavement is in service, which aggravates the continuous damage to the runway structure [2] and poses a significant threat to the taxiing safety of the aircraft. The traditional means of void detection can only be carried out when the airport is out of service, and they are labor-intensive, material-intensive, and time-consuming. The runway health condition cannot be known in real time. Therefore, if the relationship between the runway dynamic response and pavement slab void can be obtained under the action ofaircraft taxiing load, runway response information can be collected using a reasonable arrangement of sensing devices, and the pavement slab void can be grasped in real time. In airport engineering research, relevant institutions and researchers have analyzed the pavement response caused by aircraft load and environmental impact by deploying sensors on the runway, thus promoting the development of airport runway health monitoring [3; 4; 5; 6]. [PERSON] et al. proposed a method for predicting the performance changes of airport concrete pavement slabs when subjected to temperature and humidity using the measured runway strain response data from sensors [7]. However, measured data are not easily available and can be distorted [8]. Therefore, runway surface unevenness is used as the vibration excitation source to establish the aircraft-runway coupled vibration relationship, which is required for the further analysis of the vibration response. It has been found that runway surface unevenness has a significant effect on the vibration response of the airframe when the aircraft taxies [9]. [PERSON] et al. proposed a calculation method for the transient response of a runway structure under aircraft moving load by using the aircraft-runway coupled vibration relationship [10]. Many scholars have studied runway structure dynamic response and specific vibration law under complex moving loads by establishing reasonable runway finite element models [11; 12], as well as the response of rigid pavement of conventional and snow-melting airports under aircraft loads, temperature loads, and their coupling effects [13]. In a study of the dynamic response of rigid runway pavements, [PERSON] et al. found that the skidding speed significantly affects the dynamic response when skidding lift effects and vibration effects are considered [14]. It is necessary to analyze the lift effect of the aircraft. Meanwhile, according to the stochastic nature of pavement unevenness variation under dual main landing gear, the fuselage rollover rotation needs to be considered when modeling aircraft-runway vibrations. In concrete road panel debonding identification studies, the traditional falling weight deflectometer (FWD) is still an effective device for road panel void detection [15]. Due to the relative safety, high efficiency, and strong observability of airport pavement defect evaluation conducted using ground-penetrating radar (GPR), GPR has been used to identify different the void states of pavement structures [16; 17; 18]. It has been shown that the structure's material properties, stiffness, and other parameters under real-time dynamic loading directly affect the vibration response of the structure [19; 20]. When a wavelet packet transform is used to analyze vibration signals, the energy distribution in each frequency band is susceptible to the structural parameters of the vibration source [21; 22]. It also has good robustness to noise [23; 24]. Therefore, analyzing vibration signals makes it feasible to analyze the structural health condition.