Study On Calculation Method And Prediction Model Of Carbon Emission From Highway Tunnel Construction

In recent years,China's road tunnels have developed rapidly in recent years in China.The ever-increasing tunnel construction consumes a lot of resources and energy,and at the same time,emits abundant greenhouse gases into the environment.The construction of large-scale transportation facilities has increased the emission reduction pressure of China's road tunnel industry.However,the current research on energy saving and emission reduction in tunnels is concentrated in the operation stage.Green technologies such as smart ventilation and lighting technology,and geothermal heating are continually developing.In contrast,research on emission reduction in the construction stage is relatively limited.Relevant scholars have carried out calculations on the carbon emission level of road tunnel cases.Still,they have not conducted in-depth research on the calculation methods,influencing factors,and carbon emissions uncertainties.Considering the massive scale of tunnel construction in China,emission reduction during the construction phase will result in significant environmental benefits,which is of great significance to realizing China's national strategy for energy conservation and emission reduction.Based on the Doctoral Innovation Fund of Southwest Jiaotong University,"Research on the Impact Mechanism,Prediction Model and Emission Reduction Strategy of Mountain Highway Tunnel Construction Carbon Emissions(2019-2020)",this thesis studied the calculation methods and prediction models of carbon emissions for highway tunnel construction.The main works include:1.The tunnel quota system was used and combined with the modular LCA method.Aiming at the flaw of low utilization rate and high cost of traditional calculation data,a carbon emission calculation path oriented to unit engineering volume was proposed.A modular calculation method of carbon emissions for tunnel excavation and support was established.An inventory of primitive inputs and carbon emissions for tunnel construction under the baseline scenario were provided.Through the sensitivity analysis of the carbon emission calculation of the engineering case,the author found the key influencing factors of the carbon emission of material transportation and collection and processing during the construction phase: material recycling and material transportation from the market to the tunnel site.2.To further excavate the impact mechanism of carbon emissions for tunnel construction,the author used the modular calculation method and inventory to calculate the carbon emissions from excavation and support of the actual tunnel lining design cases per linear meter.The carbon emission characteristics of different modules or collections of modules were analyzed.The geological conditions of surrounding rock involved in the cases include rock mass grade,buried depth,and rock mass subgrade.The key factors influencing carbon emissions from tunnel excavation and support were excavated with correlation analysis methods.The theoretical prediction formula of carbon emissions was obtained by regression fitting.3.Based on China's highway tunnel design specifications and existing cases,typical engineering quantity calculation models for highway tunnel lining construction were established.The modular carbon emission calculation method was used to analyze tunnel design parameters' influence on the carbon emissions from tunnel excavation and support.It makes it easier for tunnel designers to estimate the emission reduction potential brought by optimizing design parameters in the design stage and provides an empirical reference for clarifying the optimal low-carbon design plan.4.To analyze the uncertainty of carbon emissions from tunnel construction,firstly,through data quality evaluation and literature research,the authors determined the distribution types and value intervals of the input parameters.A reasonable sample capacity of Monte Carlo simulation was given based on the calculation results' convergence effect.Then the uncertainties of the primitive carbon emissions of tunnel construction were analyzed.Moreover,fitting models of primitive carbon emissions through the preprocessing and fitting of carbon emissions samples were established.Finally,the analysis scenarios were set according to the current optimization for tunnel design parameter and the emission factor trend,the uncertainties of overall carbon emissions from tunnel lining construction were analyzed.