Study of Influential Factors and Measures for Low Carbonization During the Construction of Shield Tunnels
In tunnel engineering at present,carbon emissions are generally estimated during the planning design stage or obtained by statistics of total emissions after completion.However,the difference of carbon emissions in each ring and relevant influential factors are seldom considered.For this paper,based on the emission coefficient method,real-time statistics were determined regarding the in-situ energy consumption of the South Hongmei Road tunnel,and the actual carbon emissions per ring were obtained.Furthermore,the difference of the actual carbon emissions in each ring is analyzed and discussed by considering the parameters of stratum and construction.The results show that:1) the average carbon emission per ring of shield tunnelling is about 56 t,with material-generated carbon emissions being around 93％,and for the studied case the carbon emission was reduced by approximately 12 000 t (corresponding to the total emissions produced by 200 rings) by means of depth grading and steel-bar reduction;2) for construction-generated carbon emissions,shield tunnelling in the ⑦2 silty sand layer features high penetration resistance,high cutterhead torque,and highly damaging effects on the slurry,so its carbon emission per ring is about twice of that of the ⑤3 clayey silt layer,and the carbon emissions can be effectively reduced by avoiding a long-distance tunnel buried in the ⑦2 silty sand layer,while the shield advance distance and the buried depth have little effect;and 3) the carbon emissions generated by a one-day stop of shield driving is about 4 400 kg,it is therefore important to improve the advancing efficiency of the shield and to avoid long shield stoppages during tunnel construction.The daily average shield advance rate should be more than three rings—this can reduce the average emissions per ring by at least 60％ compared with a one-ring advance rate per day.
NETL
NSTL
万方数据
维普
