The Research Of Dust Emission Flux And Control Measure In Building Groundwork Of Xi'an City

In the method of comparing and analyzing the model value with the observation value, the study based on DPM(Dust Production Model) is carried out in the article and sampled the building groundwork surface in Ji tai village of Xi'an City.The article mainly uses the dry filter analysis to measure the micro-aggregates size distribution, and the micro-aggregates size distribution parameter for simulating the dust emission flux;According to the micro-aggregates size distribution parameter, roughness length from the simulation of ground situation threshold friction velocity and friction wind speed;Obtain the observation dust emission flux from the experiment;Establish the parameter scheme to modify DPM model which can be used on building site of Xi'an City.For building groundwork surface of Xi'an City, The micro-aggregates size distribution can be expressed as a mixture of two lognormal mass size distribution populations, which correspond to very fine sand, medium fine sand, the mass median diameter of them is respectively 61μm and 192μm, and standard deviation of them is respectively 1.21 and 1.13, proportion of the micro-aggregates mass is respectively 44% and 56%.The roughness length of the soil surface is between 0.00015~0.00348m, average roughness length is 0.00093m, and it is similar with the roughness length of less vegetation dune, sand cropland, less than the surface covered with most vegetation and large particle.Wind velocity and roughness length influence the friction velocity, the range of average friction velocity is 0.058~0.092m/s. The threshold friction velocity of the soil surface is about 0.082m/s, less than the surface covered by vegetation, sand, large particle. It is easier to produce dust emission.The dust emission flux of building groundwork in Xi'an is l~33μg/m~2s, the simulation dust emission flux is about 0~97μg/m~2s. While the friction velocity is between 0.108~0.136m/s,though the simulation one is 2 —6 times more than observed dust emission flux, it can reflect the reality best.According to the results, the parameter project basing on the dust emission flux of building groundwork in Xi'an, and original DPM model can be modified as follows: Fh =3.4*l()-8/t/*3 f {\ + i)According to the research of dust threshold mechanism and DPM model, the efficiency methods to decrease dust emission flux are watering intermission to increase the surface roughness length, setting separation wall to reduce wind velocity, enhancing integration administer of government and establishing corresponding criterion.