Study On Dust Generation Mechanism And Diffusion Rule Of Earthwork Construction In Xi'an

In recent years,the urbanization of Xi'an has developed rapidly.The large-scale expansion of urban areas has led to an increase in the construction volume of large-scale land development projects.However,the urban ambient air quality in Xi'an in2016-2018 is worrying.In addition,Xi'an City is also a typical collapsible loess area.This kind of soil material is easy to dust in the earthwork construction during the earthwork construction stage of the project construction project.The earthwork filler and the earthwork particles attached to the bare soil surface are easily separated from the original bound surface by the weakening of the viscous force under the external disturbance,and the two-phase flow is formed by the wind field lifting,which causes serious pollution to the local area and even the urban atmospheric environment.In addition,the earthwork particles will also act under the action of external force,such as rolling,when the combined force of the force is greater than the critical anchoring load,it will also rise to form earth dust.Xi'an City actively responded to the policy of curbing flood control and emission reduction.When the pollution came,the construction units of the city stopped production and stopped production.The“one size fits all”shutdown mode made the construction enterprises lose a lot of economic losses,and the“one size fits all”shutdown mode lacked reference and guidance.Standard regulations.The dust emission from the construction of earthwork in Xi'an and the environmental pollution caused by dust have attracted the attention of engineers and environmental protection personnel.It is clear that the mechanism of dust production and its diffusion law in the construction of earthwork in Xi'an has become an important issue to be studied and solved.To this end,the following research work is carried out around the above issues:?1?The nonlinear regression fitting of the soil dust concentration sample data obtained in the test phase is carried out,and the TSP,PM₁₀ and PM_2.5 concentration prediction models are obtained.The reverse prediction results show that the prediction effect is ideal;the PM₁₀ concentration model is taken as an example.y_PM10=-0.2781x⁴+5.045x³-20.98x²-16.031x+342.53.In the particle size analysis study,61.24%of the earth dust particles have a particle size of not less than 10?m.?2?Further research on the correlation between soil dust concentration and meteorological factors,and study on urban environmental temperature,relative humidity,wind direction and wind speed in Xi'an;taking the correlation between PM₁₀0 and meteorological factors as an example,earth dust particles PM₁₀ The concentration and temperature parameters were significantly positively correlated on both sides of the 0.01level;the relative humidity was significantly positively correlated on both sides of the 0.05level;and the wind speed and wind direction parameters were significantly negatively correlated on both sides of the 0.05 level;thus clearing the meteorological factor to the earth dust concentration value Influence characteristics.?3?Defining the dust-producing force and refining the classification,constructing and perfecting the corresponding theoretical numerical model,determining the critical anchoring load of the earth-lifting dust on the basis of the dust-producing force,and using the numerical model to characterize the dust-generating mechanism of the earth.According to the research,the dust-producing force affecting the dust concentration of earthwork construction should focus on the effects and influences of gravity,induced airflow,vibration effect and aerodynamic drag.?4?Establish a corresponding emission model for the dust source points in the earthwork project.The model covers emission factors and emissions.The pollution model is rationally corrected based on the characteristics of nighttime earthwork construction and environmental climate factors in Xi'an.The study found that earthwork loading and unloading operations have the highest dust emission,PM₁₀ emissions amounted to31795.09kg,while earthworks dumps had the least amount of dust emissions,and PM₁₀emissions were only 16.91kg.Based on the above research results,the development of a reasonable and effective dust reduction and dust suppression strategy.