Case Analysis Of Construction Ventilation In Long Railway Tunnel

With the continuous increase of railway construction in central and Western China,the coverage of road network and the density of road network are increasing,and the railway transportation network is gradually improving.The mountain ranges in Western China are various in vertical and horizontal directions and geology.Railway construction planning inevitably develops towards high altitude long tunnel project.It is precisely because of the progress of long tunnel and complex geological tunnel construction technology that the necessary construction experience and technical reserve are provided for high-speed railway to cross mountains.Different from the climate conditions in the central and Eastern plains,the high altitude,low air pressure,cold climate and thin air in the western region,highland construction ventilation has always been a major technical problem in tunnel engineering,and is a key technical problem restricting the construction of long tunnels.Because of its complex influence factors and higher technical requirements,it is impossible to simply copy the research results of tunnel construction ventilation in low altitude areas.Efficient ventilation circulation system and good tunnel working environment are the necessary conditions to maintain the normal operation of machinery and equipment,ensure the duration,safety and quality of the project,and are the safety baseline related to the health and life of the workers.Therefore,the suitability and rationality of the ventilation scheme and the actual ventilation effect are of great significance to the smooth and safe construction of the tunnel.Based on the construction ventilation case of Dangjinshan Tunnel on Dunge Railway,this paper analyzes and studies the ventilation technology and auxiliary safeguard measures during the construction of long tunnels in plateau area by means of literature study,qualitative theoretical analysis,quantitative ventilation calculation and case study.The main contents are as follows:This paper focuses on the characteristics and difficulties of ventilation in the construction of long and long tunnels in Plateau areas;systematically discusses the operation principle,advantages and disadvantages of main ventilation modes during tunnel construction under the existing technical conditions,analyses the applicable conditions and key points of construction layout,and provides a reference basis for the selection of ventilation modes;and summarizes and sorts out the guidance for tunnel construction.Relevant fluid mechanics theory and principle of ventilation design make theoretical preparation for construction ventilation calculation;summarize and summarize the calculation methods of air volume and pressure under different ventilation modes as the basis of ventilation equipment selection,and consider the calculation and selection of relevant technical parameters.On the basis of the above research work,combined with the documents of Dunge Railway Dangjinshan Tunnel such as Design Instructions,Construction Organization Design and Constrution Ventilation Scheme,this paper analyzed and explained the general situation of the project,engineering characteristics and difficulties of construction ventilation,and then carried out a detailed study on the five-stage layout of construction ventilation in 2#inclined shaft area.The ventilation calculation and equipment selection are strictly deduced.2#Inclined shaft construction is divided into five stages.Ventilation roadway includes inclined shaft,horizontal guide,cross passage,main tunnel and shaft.Each working face is opened in sequence according to construction sequence,and tunnel ventilation is arranged in five stages according to the advance of working face.Because of the interference of multi-working face and multi-working procedure in limited space,ventilation organization arrangement should be considered in accordance with the principle of economy and feasibility,which is a complex and arduous system engineering.In addition to summarizing the control points of dust removal measures for special ventilation schemes,the paper further supplements and improves the auxiliary measures such as dust reduction and dust reduction,and puts forward suggestions for tunnel ventilation management.While continuously adjusting and optimizing the construction ventilation scheme,other auxiliary measures such as construction technology innovation and the use of large supporting machinery are also effective ways to reduce dust pollution and improve the tunnel environment,which should be integrated into the unified consideration of tunnel environmental protection during construction.The ventilation scheme for the construction of the 2#inclined shaft area of Dangjinshan Tunnel has received good ventilation effect in the practical application of the whole project period.The ventilation requirements of each working face have been met.The working environment of the tunnel basically meets the standard.It effectively guarantees the smooth passage of the tunnel in the aspects of workers’health,project quality and safety,schedule and so on.Inclined shaft,main tunnel and parallel guide tunnel shoulder the heavy burden of ventilation in single heading excavation.The vertical shaft and cross channel share the ventilation pressure of each working face at the same time.They ingeniously use each ventilation roadway to form local ventilation cycle,coordinate and connect the ventilation work in each stage of construction,thus forming a dynamic and orderly ventilation circulation system in complex construction environment.Through case study,it is concluded that long-distance single-headed excavation is the difficulty and key point affecting the ventilation of long and long tunnel construction.It is an effective method to solve the environmental problems of tunnel construction by using auxiliary tunnels(parallel guide tunnels,inclined shafts and vertical shafts)to promote the ventilation organization in stages during the construction period,which can be used for long and long tunnels in plateau.It can be popularized to draw lessons from the formulation of special construction ventilation scheme and site construction organization arrangement.