| In recent years,with the development of urbanization,impermeable surface of urban increased,which damaged the original hydrological cycle system.The groundwater runoff increased,causing the city waterlogging.China’s scholars learned the concept of Low Impact Development(LID),then proposed the construction of sponge city strategy,which aimed to solve the urban waterlogging problem with technical means of Low Impact Development.The central concept of LID is the source control,which means control most of the runoff at the beginning of the drainage system,thereby reducing the load in the drainage network system.Residential area,as an important land type in the city,is one of the starting points of urban rainwater drainage system.Residential area plays an important role in urban rainwater control system.This paper took the fenghuayuan community as an example,and studied the planning and design method of reconstructing the original greenbelt to sunken greenbelt which can improve the waterlogging capacity of the area.On the one hand,the infiltration performance of the sunken greenbelt is calculated: the upper limit of the design height of overflow inlet is calculated according to the duration of submergence tolerance of the grass and the formula of rainwater infiltration.Sunken area is calculated according to the annual runoff control rate and the water balance model.The depth of sunken greenbelt and the number of overflow inlets is calculated according to the drainage performance of overflow inlet and designed rainfall intensity.On the other hand,the priority distribution of the sunken-reconstruction area is discussed by analyzing the shape and position of the sunken greenbelt,and the grade of reconstruction property is put forward by analyzing the influencing factors of the modified area arrangement.Then,based on the characteristics of greenbelts,propose the principle of planning and design of sunken-reconstruction.Combined with the above two aspects of the study,analysis the relationship between the various factors,then propose the procedure of the reconstruction planning of sunken greenbelt in residential area.The studies indicate that the calculation of design height of overflow inlet is mainly affected by the duration of submergence tolerance of the grass and the soil permeability.Sunken area is mainly affected by the height of the overflow and the designed rainfall.The depth of sunken greenbelt is mainly affected by the designed rainfall intensity and the spec of the overflow inlets and the number of overflow inlets.The sunken greenbelt should be given priority to the belt shape,and close to the rainwater pipe and the impervious surface.Suggest the procedure of the reconstruction planning.Firstly,calculate the height of overflow inlet and sunken area.Secondly,planning the distribution of sunken-reconstruction area.Thirdly,calculate the depth of sunken greenbelt and the number of overflow inlets and locate the overflow inlets.Based on the parameters and distribution of the sunken greenbelt,this paper propose a completely method of the reconstruction planning of sunken greenbelt in residential area,and raise some suggestions on strategy and implementon and management to the construction of sunken greenbelt.Wish to provide some reference for related researchs and projects. |
