斜拉桥全寿命周期碳排放计算模型

Carbon Emission Calculation Model over the Life Cycle of Cable-Stayed Bridges

为助力建筑业实现“双碳”目标,对斜拉桥的碳排放量化模型展开研究.将斜拉桥的全寿命周期划分为设计规划、建材准备、施工、运营维护以及拆除报废5个阶段,界定其碳排放边界,梳理碳排放源.采用碳排放因子法逐一建立各个阶段的碳排放计算模型,并对宁波杭州湾新区杭州湾大道跨十一塘江斜拉桥进行定量分析.计算结果表明,案例斜拉桥全寿命周期碳排放量为185900.41 t,主要在运营维护阶段和建材准备阶段产生.各阶段碳排放占比分别为0.04%、45.34%、0.58%、50.75%和3.29%.就综合质量碳排放量而言,案例斜拉桥建设期上部结构最大,为0.78 t(CO_(2)e)/t;附属设施次之,为0.34 t(CO_(2)e)/t;下部结构最小,为0.23 t(CO_(2)e)/t.通过不同桥型间的碳排放对比(设计规划阶段除外)可知,案例斜拉桥与其他3种桥型的全寿命周期碳排放规律略有不同,占比最大的是运营维护阶段,占比最小的是施工阶段.就桥面单位面积碳排放而言,悬索桥最大,为11.22 t(CO_(2)e)/m^(2);混凝土梁桥为6.48 t(CO_(2)e)/m^(2);斜拉桥为4.96 t(CO_(2)e)/m^(2);钢混组合梁桥最小,为4.45 t(CO_(2)e)/m^(2).本文建立的碳排放计算模型可用于指导桥梁选型、运维策略,同时为后续相关标准的出台提供了科学依据.

In order to help the construction industry achieve the“double carbon”goal,a carbon emission calculation model was developed for cable-stayed bridges.The life cycle of a cable-stayed bridge was divided into five stages,namely the design,materials preparation,construction,operation and maintenance,and demolition stages.The carbon emission boundary was defined,and the carbon emission sources were sorted out.The carbon emission factor method was used to establish the model for calculating the carbon emission for each stage.The life cycle carbon emissions of the Hangzhou Bay Avenue Cable-Stayed Bridge across the Eleven Tangjiang River in Hangzhou Bay New District of Ningbo were estimated to be 185900.41 t,and the contributions of five stages were 0.04%,45.34%,0.58%,50.75%,and 3.29%,respectively.Thus,the bulk of the estimated carbon emissions was attributable to the operation and maintenance and the materials preparation stages.In terms of the share of comprehensive mass carbon emissions,the superstructure of the case cable-stayed bridge was the largest during the construction period at 0.78 t(CO_(2)e)/t,followed by the ancillary facilities with 0.34 t(CO_(2)e)/t,and the lower structure had the smallest share with 0.23 t(CO_(2)e)/t.A comparison of the carbon emissions(excluding the design stage)among different bridge types showed that the distribution of the life cycle carbon emissions of the case cable-stayed bridge was slightly different from those of three other bridge types considered in this study.The largest proportion of emissions for the cablestayed bridge was attributable to the operation and maintenance stage,and the smallest proportion to the construction stage.Among the various types of bridges,the suspension bridge had the maximum carbon emission per unit area of the bridge deck,with 11.22 t(CO_(2)e)/m^(2),the concrete girder bridge had 6.48 t(CO_(2)e)/m^(2),the cable-stayed bridge had 4.96 t(CO_(2)e)/m^(2),and the steel-concrete composite girder bridge had the least,with 4.45 t(CO_(2)e)/m^(2).The carbon emission calculation model established in this study can be used to facilitate bridge design and development of a strategy for its operation and maintenance,and provide a scientific basis for the subsequent introduction of relevant standards.