Study On Urban Surface Rainwater Infiltration Capacity In The Guanzhong Area

With the accelerated pace of urbanization, increasing urban harden the ground,reducing the amount of rainfall runoff infiltration, there was a series of urban flooding problems. Guanzhong area is located in the distributed collapsible loess area. Urban surface inevitably encounters the problem of collapsible deformation eroded by rain.Therefore, combined with infiltration law of urban surface of Guanzhong area to solve the urban rainfall infiltration problems is imminent.At present, foreign scholars put forward the concept of low-impact development,the purpose is to solve a series of environmental problems such as urban rainfall infiltration, etc. The core of the successful implementation of LID is adopted to local conditions, now develping LID in the losse region is unprecedented. In this paper,through rain infiltration test and variable head infiltration test to study the sunken green space technology, analyze the role of sunken green space to increase rainfall infiltration,reduce urban flood disaste. At the same time, under conditions of increased rainfall infiltration, calculation the effect depth of urban green space surrounding loess subgrade by the rainfall.The results showed that:(1) Different types of underlying surface infiltration test results show, the law of infiltration rate index show: Residential Green(7.02×10-2 cm/min) > Campus Green(6.48×10-2cm/min) > Treading road(2.79×10-2cm/min) > Park Green(2.55×10-2cm/min) > municipal Green(2.25×10-2 cm/min) > Compacted soil(0.9×10-2 cm/min);90min cumulative infiltration show: Residential Green(5.27 cm) > municipal green(2.35 cm) > Campus Green(1.98 cm) > Park Green(1.73 cm) > Compacted soil. Cause infiltration rate differences include soil bulk density, porosity, soil texture, soilconfiguration, it was found that the existence of large pores and cracks significantly improve soil infiltration capacity;(2) Surface soil infiltration rate restricts the overall soil infiltration capacity; Heart soil infiltration rate does not increase more than top soil infiltration capacity of the entire soil. But it can be inferred from theory: When the heart of the soil infiltration capacity is less than its upper topsoil can impled water infiltration and makes the soil infiltration capacity of the entire decline;(3) The depth of sunken green space is generally 5 ~ 25 cm, its storage capacity is proportional to the concave depth(infiltration Head). Under the same infiltration rate,sunken green space storage infiltration much more than ordinary green;(4) Infiltration depth with increasing duration of rainfall increases gradually, The results show: Within 12 hours different types of urban green space, loess rainfall infiltration depth presented: Residential Green(1.79 m) > municipal Green(1.43 m) >Park Green(1.39 m) > loess(0.35 m);(5) The depth of rainwater infiltration impact loess roadbed is approximately 2m.The depth of the low order story is 5m,ande high order story is 1.79 m,at the xi’an urban area, collapsibility loess present lenticular discontinuous distribution,in the measures of LID,we can apply ‘Deep penetration intubation’keep the stable of the roadbed without contacting the story of collapsibility loess;...