## 1 Introduction  
At present, the study of wind parameters in valley areas is one of the hot spots of wind engineering research. In mountainous valley areas, the temporal and spatial variations of wind parameters are complex, and there is no uniform law. The influence of wind on the design, construction, and service of long-span bridges cannot be ignored, and are even among the controlling factors. Research on the wind characteristics of a valley is mainly based on field measurements [1,2], wind tunnel tests [3], and numerical simulations. Although field measurement can directly obtain the wind parameter data at the measured position, it is time-consuming, labor-intensive, and requires huge investment, and the obtained wind parameters are limited in quantity, time, and space. On the other hand, the wind tunnel test is widely used, but there are some problems with the accuracy of feature flow simulation and scale model production. Finally, with the development of computer technology, computational fluid dynamics (CFD), the convenient operation and lower cost, numerical simulation is more widely used, and the reliability has been verified [4,5]. In terms of CFD simulation, [PERSON] and [PERSON] [6] discussed the application of three turbulence models--modified k-\(\epsilon\) model, standard k-\(\omega\) model, and the standard--and it was found that was more consistent with the experimental data than the other two models. [PERSON] and [PERSON] [7] used the pseudo-compressibility approach, large eddy simulation (LES), an arbitrary Lagrangean-Eulerian (ALE) formulation, and an explicit two-step Taylor-Galerkin method to simulate two-dimensional viscous turbulence. [PERSON] et al. [8] combined the weather model, RAMS, and the computational fluid dynamics model, FLUENT, into a one-way offline nested modeling system. [PERSON] et al. [9] proposed a phase delay spectrum model to represent the spatial coherence of random wind fields. [PERSON] et al. [10] used numerical simulation to study the neutral stratified turbulent boundary layer on a two-dimensional hill. [PERSON] et al. [11] proposed a method of fine-tuning observations based on spatial correlation, which could consider the impact of complex terrain. [PERSON] et al. [12] proposed an improved scheme involving only a basic random variable dimensionality reduction mode and non-uniform wavenumber interval. [PERSON] et al. [13] used the RANS/LES hybrid model to numerically analyze the external flow field of the terrain, studied the wind speed amplification factor and the change law of wind parameters along the height, and discussed the canyon effect and thinning effect of the wind field. Based on the twisted wind profile conditions of the quasi-steady state theory, [PERSON] et al. [14] evaluated the influence of wind field characteristics on the buffeting response of a variable cross section bridge tower, where the bridge is located in a trumpet-shaped mountain pass. [PERSON] et al. [15] used the CFD-based numerical simulation method to establish a numerical model of the canyon bridge-tunnel junction. [PERSON] et al. [16] analyzed the wind directions' effect on wind characteristics over complex terrain by CFD. [PERSON] et al. [17] also discussed the influence of wind direction on wind speed along the bridge axis. In summary, scholars have undertaken many numerical studies on wind parameters at mountainous bridge sites, but only one or two of the factors such as oncoming wind direction, inlet wind speed, wind speed profile, or surface roughness were considered. However, the simultaneous influence of these initial conditions on wind parameters has not considered, and their influence degree of initial conditions remain unexplained. On the other hand, the analytic hierarchy process (AHP) is a combination of qualitative and quantitative decision-making methods that are widely used in safety production technology evaluation, reliability evaluation, water quality index research, and other areas.