Numerical Study On Spatial Diffusion And Hierarchical Control Measures Of Construction Dust

The construction dust can not only cause serious pollution to the urban environment,but also affect the growth of vegetation and lead to various respiratory diseases,which harms the health of people and the progress of economy.The study of the spatial diffusion of construction dust can help to develop management and control measures for construction dust prevention and control,and promote green urban development.Based on the theory and technology of Computational Fluid Dynamics(CFD),the following research work has been done on the spatial diffusion of construction dust and the hierarchical control measures.(1)There may be significant differences in the characteristics and distribution of construction dust in different areas at different construction stages.Taking the actual construction project as the research object,detailed measurements of construction dust concentrations are made for the earthwork stage et al.The construction dust concentrations in each area of each stage before and after dust suppression measures are compared and analyzed.The study identifies the most polluted construction phases and construction areas,which paves the way for the study of dust spatial dispersion characteristics.(2)The spatial diffusion pattern of construction dust may be similar in different construction stages.The accuracy and applicability of the power function,Gaussian function and exponential law models in describing the diffusion of construction dust in horizontal and vertical directions are compared and analyzed,based on the monitoring data of construction dust concentration in horizontal direction of 21 groups of construction sites and vertical direction of 36 groups of construction sites.The results show that the proposed exponential model is applicable to describe the diffusion of construction dust in both horizontal and vertical directions.The spatial diffusion of construction dust is reproduced based on the CFD simulation,and the applicability of the proposed exponential model on spatial diffusion of construction dust is verified based on the CFD results.(3)The incoming wind velocities and fence heights are the key factors affecting the spatial diffusion of construction dust.Taking a construction site as an example,the construction dust data of a certain period is selected for CFD simulation.By analyzing the meteorological wind velocity data during the construction period of the site,6kinds of incoming wind velocities with exponential law are selected,and 6 kinds of fence heights are chosen.The CFD simulations of construction dust spatial dispersion are carried out to compare and analyze the spatial diffusion characteristics of construction dust under different fence heights and incoming wind velocities.In order to comprehensively evaluate the impact of construction dust on human body and external environment,and the effects of incoming wind speed and fence height on dust pollution are quantified and analyzed.(4)According to the influence degree of construction dust,the pollution severity grading standard of construction dust is proposed.Based on the horizontal distance from the construction site,the area around the building construction is divided into 3 pollution level zones.The graded warning method and detailed process for the severity of construction dust pollution are proposed according to the construction dust concentrations,and a construction dust pollution hierarchical control approach is developed for different pollution levels.This study can provide a reference for the spatial dispersion analysis of construction dust,and the proposed graded control measures for construction dust can effectively reduce the concentration of construction dust,while controlling the cost of dust suppression,maximizing the ambient air quality and improving the living and traveling environment of residents.