Study Of Structural Design & Hydrological Properties Of Large Permeable Parking Lot In Sponge City

With the continuous advancement of urbanization and the rapid development of economy and society in China,the number of car ownership has increased exponentially,and the area of car parking has increased continuously.A large number of impervious materials have been used in urban construction which blocks the exchange of material and energy between soil and environment,resulting in the destruction of urban ecological environment such as"urban heat island effect",urban waterlogging,air pollution and other issues.Based on this,the structure of large-scale permeable parking lot in sponge city is proposed in this paper to solve the problem of rigid pavement impervious to water in traditional parking lot and the contradiction between bearing capacity and planting plants in common permeable pavements.This paper studies the hydrological characteristics of permeable pavements,the permeable function design indexes of permeable parking lot are put forward according to the seepage mechanism of permeable pavements.The permeable function requirements and structural strength requirements of permeable parking lot are combined to design permeable parking lot structure.The structure consists of150 mm cement concrete face slab(the opening rate is 53%),30 mm coarse sand leveling layer,300mm graded macadam base and soil foundation,and the reinforcement ratio is 0.63%.Use the software ABAQUS to model the parking space of the permeable parking lot under static load.The change rule of stress and strain of the structure layer of the permeable parking lot is studied.When carrying 18 tons,2 axes and 6 rounds of bus,the bottom tension stress of concrete slab in permeable parking lot is 0.8025MPa,and the displacement of concrete surface is 0.7075 mm,which meets the strength design requirements.Artificial rainfall simulation experiments were carried out for permeable parking lot,and the role of permeable parking lot in runoff control was quantified by means of SWMM model.SWMM simulation results show that the permeable parking lot has a good effect on rainwater runoff regulation and storage,mainly reflected in the reduction of total runoff,peak flow,runoff generation time,peak time delay.The LID model reduces the total runoff volume at 1a,10a,20a,50A and 100a,respectively,541 m~3,1082 m~3,1243 m~3,1297 m~3 and 893 m~3.The total runoff reduction rate is 100%,100%,100%,81.16%,57.12%.The peak runoff volume is reduced by 0.232 m~3/s,0.461 m~3/s,0.522 m~3/s,0.583 m~3/s and 0.307 m~3/s,and the runoff yield time is delayed by 36 min,31 min,256 min,5 min,respectively.The time was delayed 109 minutes,102 minutes,95 minutes,9 minutes and 6 minutes respectively.In addition,whether for the reduction effect of total runoff and peak flow,or the delay effect of runoff generation time and peak-to-peak time,the operation effect of permeable parking lot structure model is better.The research in this paper can provide theoretical support for the structural design of large-scale permeable parking lot in sponge city.It can improve the durability of parking lot structure and meet the requirements of permeability and ecology.