Analysis And Evaluation Of Embodied Carbon Footprint Of Subway Station Construction

With the rapid development of urban rail transportation,in addition to carbon emissions from the embodied phase of the subway,carbon emissions from the subway construction process cannot be ignored.In 2022,803.12 kilometres of new subway lines had been built in China,with 544 new subway operating stations.The energy-consuming and consumable construction methods of subway underground stations put enormous pressure on the environment.Implementing the concept of green,low-carbon and efficient construction in the whole process of subway planning and construction,and carrying out metrological assessment of the carbon footprint of the embodied phases of subways can help promote high-quality development in the transport and construction sectors.This study conducts relevant research in the following areas:Firstly,this research reviewed and analyzed related thesis on the carbon footprint of buildings and carbon footprint in the field of subway construction at home and abroad,established the theoretical basis of carbon footprint analysis in the embodied phase of subway station construction,clarified the system boundary,evaluation steps and index system of carbon footprint in the embodied phase of subway stations,delineated the scope of engineering volume data to be included in carbon footprint measurement,and constructed a subway station carbon footprint measurement model and a database of carbon footprint factors in the embodied phase of subway stations with the characteristics of timeliness and locality.Secondly,taking a station of Guangzhou Metro as an example,a carbon footprint measurement model was used to measure,compare and analyse the carbon footprint of the embodied phase of the three construction methods of the case station,namely,open excavation method,cover excavation method and cover excavation reverse method.The results show that（1）the embodied phase footprint of the cover excavation method of the case station is3.46tCO_2e/m²,which is relatively more low-carbon than the other two methods;（2）the material production phase of all three methods accounts for more than 84%of the embodied phase carbon footprint,which is the main source of the embodied phase carbon footprint of the subway station;（3）for the same cost of the subway station,the carbon footprint of the open excavation method is 13.77%higher than the cover excavation method.（3）for the same cost of subway stations,the carbon footprint of the open excavation method is 13.77%higher than the cover excavation method and 10.18%higher than the cover excavation reverse method;（4）the carbon footprint of the embodied phase of subway stations under different methods is more sensitive to changes in the carbon footprint factors of reinforcement and concrete.Finally,a comprehensive evaluation index system for low-carbon construction of subway stations is established by combining PSR theory,and a low-carbon construction evaluation model based on PSR-TOPSIS is constructed to evaluate the low-carbon construction level of cases and conduct barrier degree analysis.Through the empirical study,the validity of the evaluation model is verified,and targeted suggestions are made to improve the low-carbon construction level of subway stations.