## 1 Introduction
For the purpose of decreasing MPW, installing transverse branches [12; 13], optimizing the opening area [14; 15], cutting angles of tunnel hood [16], and hood length [17] are also proved to be effective. Research with respect to the pressure spread and waveform of the pressure waves inside tunnel predominately focus on two aspects, i.e., the prediction of compression waves and the reduction method. Field tests from three Shinkansen tunnels were earlier carried out by [PERSON] et al. [18], according to which the pressure history at different longitudinal locations and the pressure gradients in slab and ballast track tunnels were compared. Measurements denote that the strength of compression waves exponentially attenuate with the spreading distance in ballast track tunnels while the compress wave is likely to be steepened in the slab track tunnel. Through theoretical and experimental means, [PERSON] [19] and [PERSON] [20] respectively investigated the influence of tunnel length, intersection of trains, train length, and nose shape designs. Aerodynamic effect caused by the intersection of HSTs was then studied by [PERSON] et al. [21] and [PERSON] et al. [22], respectively addressing the influence of train nose length and tunnel cross-section area. Inaddition to the research focusing on the pressure wave calculation, damage evaluation of tunnel linings subjected to the pressure load induced by tunnel aerodynamic effect was studied by [PERSON] et al. (2013) and [PERSON] et al. (2014). Without doubt, tunnel aerodynamic effect has been investigated by many scholars in the past few decades by conducting full-scale test, moving model test, and numerical simulation. There is still a shortage regarding field measurements. Research in this field is restricted due to following shortcomings: (1) speed level of previous field test is relatively low (approximately 300 km/h). For example, test speed in the Terranuova Le Ville tunnel at Italian high-speed line by [PERSON] et al. (2015), Shinkansen tests by [PERSON] et al. (2016) in Japan, is relatively low. (2) testing scenarios are limited as geometry/dimension of the moving rig is predetermined; (3) most studies were conducted by simulation means while measurements from field test are still insufficient. Motivated by such gaps, the present study combined field test with numerical means. Crucial parameters, namely the transient pressure load (tunnel surface and train body) and amplitude of micro-pressure wave are both investigated. Train speed in the field test is very representative as they are regularly operated speed in Chinese high-speed railways. Higher velocities, ranged within 400-495 km/h, is simulated through numerical means which has been validated by field measurements. Correspondingly, tunnel aerodynamic effect was investigated with a wide range of train speed (250\(\sim\)495 km/h) being considered. Besides, test condition contains both train's passage and intersection, providing reliable results for various scenarios. Outcomes of the present study are expected to help improve the understanding of tunnel aerodynamic effect caused by HSTs and the pressure spreading characteristics inside and outside the tunnel.