Analysis On Raised Dust Pollution Emission During Road Subgrade Construction

Raised dust pollutant is one of the most basic and most widely distributed common air pollutants. With the rapid development of the construction of infrastructure in our country, raised dust pollution produced by road construction is increasingly serious, bringing negative effect to ecological environment and people's health. There is no systematic research on raised dust produced during the construction of road engineering (especially subgrade) until now. What's more, few reports about researches analyzing raised dust emission according to the different constructing characteristics of each section during the process of subgrade construction can be found.With the current situation in mind, taking in construction of freeway between Binzhou-Dezhou as an example and beginning with the constructing characteristic of each section of subgrade construction, this dissertation investigates the intensity and concentration distribution of raised dust emission during each stage of subgrade construction based on atmospheric diffusion theory, putting forward the engineering measures which control pollution.Firstly, through material study and field survey, the dissertation analyzes the generation mechanism of raised dust during the road construction. Based on the characteristic of raised dust emission during each stage of subgared construction, the construction process of subgrade is divided into three phases:filling, compaction and deposition, which are further divided into the following operating units:soil material loading and unloading, vehicle transportation (including constructed subgrade, construction access road, publicly paved road and unpaved road), wind erosion dust (including constructed subgrade, construction access road, publicly paved road and unpaved road, soil borrowing ground and transport vehicle loaded soil)Secondly, based on "operational unit" Emission Factor method during constructing recommended by AP-42 of U.S. Environmental Protection Agency, the dissertation put forwad the calculating models of raised dust factor suitable for each operational unit in subgrade construction and the estimation methods of emission during different constructing stage. After analyzing the atmospheric diffusion and dilution pattern of pollutants, for each operational unit during each stage of subgrade engineering, different Gaussian diffusion models are chosen respectively according the transmission and diffusion of raised dust from different source (point source, line source and area source).Finally, based on Al contract section on freeway between Binzhou and Dezhou, the raised dust emission factor of operational unit during each stage of construction of subgrade is calculated, as well as the total emission during filling, compaction, and placement. The result shows that filling>compaction>placement. And the concentration distribution is calculated using atmospheric estimation software in different pattern of point source, line source and area source. It is shown that with the increasing of distance, point source and area source emission increase to the maximum value and then decrease to the stable value, while line source emission presents a distribution pattern which change decreasingly.The research method in this dissertation helps to understanding the characteristics and emission of raised dust pollution, and can guide the quantitative calculation of emission of raised dust pollutant and analysis of spatial diffusion pattern, which can not only provide for environment protection agency the emission inventory of raised dust pollutant on the construction site of subgrade, but also provide technical methods for estimating pollution degree and making prevention measures which are effective and suitable to local technique and economical conditions.