Study On Carbon Emission Measurement And Characterization Based On LCA Expressway Tunnel Traffic

With the acceleration of urbanization and the constant growth of transportation demand,expressway tunnel,as an important part of expressway network construction,not only carries a large amount of traffic,but also produces a large amount of greenhouse gas emissions.Aiming at the current situation that there is little research on greenhouse gas emissions generated by tunnel traffic activities at home and abroad,this thesis takes Huaying Mountain expressway tunnel traffic as the object,based on the life cycle evaluation framework,uses the carbon emission factor method of H-LCA to clarify the range of tunnel carbon emissions from the metering object,system boundary,metering gas and metering unit.The calculation method of tunnel carbon emissions is proposed,and the carbon emissions are quantitatively analyzed and compared to study the characteristics and influence mechanism of tunnel carbon emissions.On this basis,the energy-saving and emission reduction strategy based on carbon emission assessment is proposed to reduce the carbon emissions of tunnel traffic and provide scientific basis for the development of urban tunnels.Firstly,the whole life cycle of the tunnel is divided into the stages of tunnel planning and design,construction and operation and maintenance,and the carbon emission of the tunnel project is analyzed,the direct and indirect influencing factors of the carbon emission of the tunnel project are summarized,and the main sources of carbon emission in each stage are determined.This thesis reveals that the carbon emission source of expressway tunnel has the characteristics of extensibility,concealment,low carbon and safety balance,constructs the common carbon emission factor database in tunnel traffic construction projects,and establishes the carbon emission calculation model at each stage of the tunnel.Secondly,combined with the existing carbon emission inventory,the carbon emission of each stage of the tunnel was calculated,the contribution of raw materials and energy in different construction stages to carbon emission was analyzed,the influencing factors of carbon emission in each stage were clarified,and the carbon emission characteristics and their interaction in different stages were revealed.According to the calculation results of carbon emission,the total carbon emission of the tunnel construction stage,operation stage and maintenance stage accounted for 32.26%,56.54%and 11.20%of the whole life cycle of the tunnel.The tunnel body engineering contributes the main carbon emission in the whole life cycle and is the main source of carbon emission in the whole life cycle of the tunnel.In order to further explore the influence mechanism of carbon emission in the tunnel construction stage,sensitivity analysis of carbon emission calculation in the tunnel construction stage shows that when the carbon emission factor of pumped concrete and steel is changed by 10%,the increased amount accounts for 4.81%and 2.98%of the carbon emission in the base period of the tunnel construction stage in the whole life cycle,respectively.It provides an empirical reference for determining the optimal low-carbon parameter design scheme.Finally,based on the establishment of vehicle speed-carbon emission model,the influence rule of design parameters on the carbon emission of mobile source in tunnel was analyzed based on different scenarios.It is found that the carbon emission of mobile source in tunnel is related to tunnel infrastructure conditions,traffic flow,vehicle speed,tunnel control measures and other factors,and has a certain regularity of influence.Under the circumstance of 24-hour vehicle flow in the tunnel,when the proportion of new energy minibuses increases by 10%,the tunnel carbon emission decreases by 765.52kg＿CO₂,that is,the carbon emission in the tunnel operation stage decreases by 3.92%.On this basis,through the calculation and characteristic analysis of tunnel traffic carbon emissions in the whole life cycle,it is convenient for relevant tunnel construction and transportation departments to estimate the emission reduction potential brought by design parameters in tunnel construction and supervision,so as to promote the sustainable development of energy conservation and emission reduction of tunnel engineering.