## 1 Introduction  
It is known that the existing structural design theory of asphalt pavement is mainly based on the multilayer elastic system theory, and the interlayer interface is assumed to be completely continuous or completely smooth [1, 2]. Certainly, each country has its own design criteria and specifications for road design. In China, based on Specifications for Design of Highway Asphalt Pavement [3], the pavement structure is also considered as a layered elastic continuous system to solve the interlayer contact problem of asphalt pavement. Additionally, a further regulation on the construction between layers is proposed in Technical Specification for construction of Highway Asphalt Pavement [4] to make the actual working state of the asphalt pavement conform to the ideal state as much as possible. The asphalt mixture layer, semirigid base layer, and structural layer of each asphalt mixture are closely combined into a whole. However, asphalt pavement is layered and rolled in layers, which leads to the fact that the contact between layers cannot be completely continuous [5]. In addition, owing to the structural depth of the surface, the surface texture of aggregate and the adhesion between asphalt films, the interlayer contact cannot be completely smooth [6]. Therefore, it is not accurate to simply regard each structural layer of asphalt pavement as completely continuous or completely smooth. To improve the understanding of the interlayer interface model, avoid the early interlayer slip failure, and establish a set of standards for evaluating the bond ability of asphalt pavement, some researchers have done much work through software modeling calculation and laboratory experiments. In 1962, the research results of [PERSON] and [PERSON] [7] showed that the interlayer interface would cause crescent-shaped or semicrescent-shaped slip cracks, which had a serious impact on pavement performance. Immediately, extensive research on the problem of interlayer bonding was performed, and many interlayer interface models were also put forward to analyze the reasons for interlayer diseases. Among them, the Goodman model is the most widely used. In 1968, the famous Goodman model was put forward by [PERSON] and [PERSON] [8] to solve the contact problem of jointed rock. They found that the interlayer shear stress is proportional to interlayer relative displacement. With continuous optimization of the Goodman model, it has become the first choice for researchers to study interlayer interface problems. Based on the Goodman model and by numerical simulation and direct shear test, [PERSON] et al. [9] analyzed and calculated the stress and strain of pavement structure with the change in the interlayer bond coefficient. The results showed that the interlayer shear strength decreases with the decrease in vertical compressive stress or the increase in temperature when the interlayer adhesion coefficient is \(10^{8}\)-\(10^{12}\) N/m\({}^{3}\), and the interlayer shear strength reaches a maximum when the amount of adhesive oil is in an optimal range. [PERSON] and [PERSON] [10] described the interlayer interface behavior through interlayer reaction modulus, shear strength, and friction coefficient after instability. In addition, [PERSON] et al. [11] studied the interlayer stiffness of different interlayer bonding materials, and believed that the material of double-layer structure has a greater impact on interlayer bonding strength than that of interlayer bonding material, and the interface bonding between the base and subgrade had the most adverse impact on pavement life. [PERSON] et al. [12] found that the type and temperature of hot mix asphalt mixture has a strong influence on the interlayer bond strength, and there is an optimal oil spread rate of viscosity-level. However, [PERSON] et al. [13] hold the opposite view that the adhesive material of interlayer interface has more influence than the amount of spread and interface conditions (roughness, etc.).