| Since the reform and opening up,my country’s urbanization has made rapid progress under the joint efforts of government policies at all levels and the active participation of the whole people,and has achieved world-renowned results.Urban metabolism is one of the basic functions of the urban ecological system.The input and output of material and energy in the urban system supports the operation and development of the city on the one hand,and on the other hand,it is accompanied by a series of problems that violate the laws of urbanization and ecological development.For example,excessive growth in energy consumption will lead to resource shortages,and excessive emissions of construction waste and carbon dioxide will cause environmental pollution.As an important part of the development of urbanization,the metabolism of the road system itself plays an important role in the material metabolism of the entire urban system.The research object selected in this paper is the road system in the Beijing-Tianjin-Hebei region,using a bottom-up material flow analysis method,focusing on the main road types and the total material stock and input and output of main building materials in the region from 2000 to 2018.Analyze its change characteristics during the study period,and conduct a preliminary analysis of its resource and environmental effects,and then further analyze the resource and environmental benefits generated when construction waste is recycled and reused as a resource.It is hoped that this Provide support for the sustainable development of the road system in the Beijing-Tianjin-Hebei region.The main conclusions of this study are as follows:(1)From 2000 to 2018,although the physical inventory of the road system in the Beijing-Tianjin-Hebei region fluctuated,it showed an overall upward trend.As of 2018,the total inventory increased from 341.11 million tons in 2000 to 1063.72 million tons,an increase of 3.12 times.The total material input was 836.31 million tons,and the total waste output increased to 862.11 million tons.The material input and output trends are similar to the total stock trends.(2)In this paper,among the four types of roads in the Beijing-Tianjin-Hebei region,the main urban roads account for the largest proportion of the stock,followed by expressways,secondary highways and primary highways.As of 2018,the total stock of the four types of road types is 673.1 million tons,164.58 million tons,123.71 million tons,and 102.33 million tons.The proportion of road material consumption structure is relatively stable,with gravel consumption and metabolism being the largest,followed by cement,asphalt and steel.(3)From the view of road system metabolic resources and environmental effects in the Beijing-Tianjin-Hebei region,the exploitation of resources and the discharge of wastes are fluctuating,but on the whole,they are on an upward trend.There has been an overall upward trend in the extraction of limestone and iron ore and in the crude oil and stone required for the processing of asphalt and gravel,from 2000 to 2018,the demand for four types of resources increased from 1,937.761 million tons,2.513 million tons,170.046 million tons and 100.62 million tons to-1.585 million tons(of iron ore),2,309.291 million tons(of Limestone),206.079 million tons(of crude oil)and 116.96 million tons(of stone).Total carbon dioxide emissions increased from 62,132,200 tons in 2000 to 195,401,700 tons.(4)Under the condition of construction rubbish is recycled,road construction for iron ore,limestone,demand for crude oil,stone four types of resources are not less than cycle through resource demand,road material of carbon emissions is also less than not circulation situation of emissions,dropped sharply increased along with the construction waste and trends.This indicates that the recycling of construction waste has a positive effect on the resource and environment effect of road system. |
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