Rain Osmosis System Of The Under Concave Green Space

As issued by the general office of the state council "the guidance about promoting the sponge city construction, the prelude about domestic advancing the sponge city construction has begun. The under concave green space as one of main engineering measures in the low impact development technologies, can accumulate, permeate and purify rainstorm runoff by effective using soil and vegetation seepage system. But The under concave green space has the characteristics of aboriginality, and at present, domestic related research is very limited, so it is great significant that we research the osmosis system of the under concave green space for increasing urban groundwater infiltration recharge, purifying the runoff pollution, cutting flood peak flow and reducing the urban flood disaster.This topic mainly researched the design of the under concave green space in Kunming from the outdoor green space test, indoor soil column test, simulation analysis and calculation, green space system integrated design four aspects. First by testing the outdoor green space got the infiltration rate of undisturbed soil in kunming city; then by indoor soil column experiment with different sand ratio improved soil, concluded the related parameters of the modified soil (including infiltration rate, porosity, for each pollutant removal rate, etc.); then use a variety of indoor and outdoor data, through the model simulation and hydraulic calculation analyze the permeability efficiency, the flood volume, the peak of overflow, peak reduction effect, flooded after the rain, water purification which of the under concave green space before and after improvement; finally combining with the existing engineering examples at home and abroad, the integrated design of the under concave green space and other infiltration facilities is discussed.The main research results:(1) Three steady infiltration rate of green space soil in Kunming are 0.942 mm/min,0.838 mm/min,0.739 mm/min;(2) the steady infiltration rate of soil is mainly affected by the moisture content, the degree of human trample, porosity, factors such as plant roots; (3) with the increase of sand content in the soil, the steady infiltration rate of soil will gradually increase, but the removal rate of pollution will gradually decrease; (4) Choosing the proportion of 70%～80% of sand and soil to improve is the most suited; (5) the steady infiltration rate of soil has much effect on the permeability and storage efficiency, concave depth has a certain influence on permeability and storage efficiency of green space, the size of green space area is important to cities’ permeability and storage in rain flood runoff; (6) after the under concave green space are improved, reducing quantity and reducing the peak efficiency increase; (7) the under concave green space and other permeability facilities combined with design can use the under concave green space -permeability tube (canal) system, the under concave green space - infiltration shallow groove, the under concave green space - infiltration pool system, etc.