Study On The Technology Of Extra-long Highway Tunnel Construction Ventilation In Plateau

With the implementation of the western development strategy in our country,the western region's traffic network is being improved gradually.Because there are a chan of mountains in the western region,the quantity of extra-long tunnel increases gradually.The features of high altitude,low air pressure and cold climate in western region cause that there are certain differences in the tunnel construction ventilation between in plateau and in plain,especially the airflow field characteristics and CO migration in the tunnel.This paper relies on a extra-long highway tunnel engineering,using the theoretical analysis,numerical simulation and field test methods,and the extra-long highway tunnel construction ventilation technologies in plateau are studied.The main works of this paper are in the following:(1)The existing construction ventilation methods are analyzed and compared in depth,and advantages and disadvantages of each ventilation method are discussed,which provides the basis for the development of ventilation scheme for highway construction in the plateau area.(2)Theoretical calculation methods are provided for the construction of the key technological parameters,and it creats the theory preparation for extra-long highway tunnel construction ventilation scheme in plateau.(3)For the long distance low air pressure that extra-long highway tunnel construction ventilation in plateau faces,the calculation method and construction ventilation scheme of the construction ventilation parameters suitable for the extra-long tunnels in the plateau area are given.(4)It calculates reasonable duct diameter and distance between duct mouth and tunnel constraint,using computational fluid dynamic software Fluent,in a certain tunnel area.(5)The airflow field characteristics and the law of CO transport in the tunnels during the construction of the extra-long tunnels in the highland area are obtained by simulating the ventilation effect of the five working conditions in each condition.(6)The construction ventilation test work was carried out for extra-long 'highway tunnel construction condition in plateau,and test datum verify that the numerical simulation and actual result are consistent.