###### Abstract  
The inhomogeneous settlement of subgrade seriously affects the safety of aircraft operation. To investigate the mechanical response of pavement slabs supported on an inhomogeneous settlement, a three-dimensional model of aircraft load-pavement structure-heterogeneous pavement was established; then, the inhomogeneous settlement conditions were simulated by setting a different reaction modulus between adjacent subgrades. Finally, both numerical simulation and experimental study methods were used to analyze the flexural tensile stress and vertical displacement of the pavement slab in inhomogeneous settlement conditions under the loading effects of typical aircrafts (A320 and B737-800). The results indicate that the strain of pavement slabs increases as the change rate of an inhomogeneous subgrade support increases. Increasing the thickness of the pavement slab and reducing the inhomogeneous subgrade support can effectively improve the mechanical performance of the pavement structure. For B737-800, with the change rate of the inhomogeneous subgrade support increasing from 0% to 85.71%, the amplitude of the flexural tensile stress of the pavement slab increased by 34%. The pavement slab with a thickness of 0.36 m experienced flexural-tensile failure. For pavement slabs with thicknesses of 0.38 m and 0.40 m, the maximum inhomogeneity of the subgrade roof support should not exceed 33% or 62%, respectively. Therefore, the effect of the horizontal inhomogeneous subgrade support caused by long-term environmental action should be considered when designing pavement slabs. inhomogeneous settlement; mechanical response; aircraft operation; flexural tensile stress; vertical displacement +
Footnote †: journal: Applied Sciences  
0000-0002-3313-3300][PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON]. reconstruction and expansion projects. This has caused the differential settlement of foundations, which is reflected in the top surface of the subgrade, and eventually causes the longitudinal cracking of the road surface [1; 2; 3; 4]. [PERSON] used a centrifuge model test combined with a finite element method (FEM) to investigate the development law of transverse differential settlement between the modern tram pile-plank-supported subgrade and the surrounding pavement subgrade and suggested a critical transverse differential settlement rate according to the requirements of allowable tensile stress [5]. [PERSON] studied the influence of stress on pavements based on granite residual soil subgrade, investigating the effects of stress-dependent water retention on settlements during rainfall and evaporation [6]. [PERSON] discussed ground settlement and pavement tensile stress under different tunnel depths and proposed displacement and stress control limitations to meet the structural stability requirements of the pavement [7]. Existing research on the settlement of transport infrastructure has tended to focus on railway, highway, pipeline, and tunnel engineering, while few studies have analyzed the inhomogeneous settlement of subgrade in runway engineering. In fact, runways have a larger aircraft load and cause greater disturbance to rigid pavements. Thus, the runways are different from railway, highway, pipeline, and tunnel engineering. Due to the difficulty in obtaining an analytic solution for dynamic problems, standard and modified finite elements are widely used in this field [8; 9; 10]. [PERSON] simulated the settlement of a soft soil foundation and the construction process using elastic-plastic finite element analysis software [11]. [PERSON] used the finite element method (FEM) to determine the surface settlement and deformation laws under different construction conditions, including the change law of longitudinal and lateral pavement settlement following the progress of excavation [12]. [PERSON] studied the dynamic response of airport pavement with various temperature and aircraft loading conditions [13].