重载车爬坡下的公路临界坡长确定

The Critical Length of Slopes on Highways for Heavy-duty Vehicles

山区公路纵坡坡度和坡长组合设置存在不合理,导致重载车辆爬坡速度下降过快,而诱发长大纵坡路段交通事故。在分析车辆爬坡过程中的受力情况及运行特征的基础上,以某重载汽车为例使用仿真软件建立动力学模型。在约束最大爬坡性能的前提下,对满载时重载车辆爬坡特性及车速衰减规律进行仿真。在车辆功率重量比一定的前提下,设计不同坡度下的重载车爬坡及不同入坡车速的重载车爬坡2种工况,研究车辆爬坡过程中速度衰减规律及入坡车速和纵坡坡度对爬坡稳定车速的影响。车速衰减曲线表明,入坡车速对爬坡稳定车速没有影响,但其与稳定坡长成正比。对于爬坡性能差的重载车辆,当入坡车速为80km/h时,临界坡长小于400m;当入坡车速为60km/h时,临界坡长小于300m,均低于《公路工程技术标准》的相关规定。因此,爬坡过程中当车速衰减超过20km/h时,需设置爬坡车道。最后,结合仿真中合理坡度和坡长的组合,提出具体的爬坡车道设置方法。

The unreasonable combination of length and grades of slopes leads to undesirable reduction of heavy-dutyvehicles^ speeds in mountain areas. Even worse, it would result in serious traffic accidents. Based on force conditions andoperational characteristics in climbing processes, a kinetic model is developed with a case study of a heavy-duty vehicle.With the restriction of climbing abilities, the characteristics of climbing and regulations of speed reduction of a fully loadedheavy-duty vehicle are simulated. With a certain power-to-weight ratio, the profiles of this vehicled climbing speed areexplored, using slope gradients and approaching speeds as two controls respectively. The attenuation curve of speedsshows that the approaching speed is positively related to the critical length of slopes, but has no influence on the steadyclimbing speed. For this heavy-duty vehicle with a low climbing performance〉 when the approaching speed is 80 km/h,the critical length is restricted to 400 m ; while the speed is 60 km/h, the critical length is restricted less than 300 m ,which are less than the corresponding value in current national standard Technical Standard of Highway Engineering.Therefore, when the speed reduction exceeds 20 km/h in climbing processes, it is necessary to set climbing lanes or relevantfacilities, which is also given according to the simulation result.