Research On Low Impact Development Technology Of Expressway Service Area Under The Concept Of Sponge City

Service area is one of the important ancillary facilities on the expressway,and its large area has high requirements for stormwater discharge.Under the background of China's vigorous promotion of "sponge city" construction with low impact development(LID)as the core concept,how to integrate the new concept of sustainable stormwater management into the planning and design of service areas,increasing the level of conservation of soil and water,advocating green development concepts,and demonstrating a higher level of public image have gradually become one of the industry's concerns and efforts.This paper firstly analyzes the connotation of sponge city and low impact development system,drawing lessons from several low impact development system cases at home and abroad,combined with Sponge City Development Technical Guide: Low Impact Development,the idea of constructing a low impact development system for expressway service areas under the concept of sponge city was put forward.Then the Pu'er tunnel service area is taken as the research object,and the rainfall characteristics of the study area are analyzed and the surface rainfall model is constructed.The surface runoff model in the study area was built based on SWMM,the parameters of the model were calibrated by observed rainfall events,the NSE was used to verify the reliability of the model,the results show that model reliability is high.Considering the site conditions,the nature of the underlying surface of study area,the spatial requirements and economic efficiency of LID facilities,the functional zoningand traffic characteristics of the service area,the selection principles of LID facilities in the service area are proposed.Based on the established surface rainfall model and surface runoff model,the parameter range with better runoff control effect of each LID facility under different rainfall return periods in the study area was obtained through model simulation.In order to compare the combined effects of different LID facilities,the evaluation system of low impact development of service area was established by using analytic hierarchy process.Finally,two low impact development schemes with different intensities are proposed for the Pu'er tunnel service area.The runoff control effect,economy and node overflow situation of the two schemes are analyzed,combined with the expert score,the calculation of the evaluation system shows that the second scheme is better.Compared with the traditional development,the reduction of the runoff peak flow and the runoff volume is 72.09% and 70.53% at 0.1-year rainfall return period,67.90% and 59.98% at 2-year rainfall return period,67.08% and 56.38% at 5-year rainfall return period,and 63.27% and 52.62% at 15-year rainfall return period,respectively.Taking Pu'er tunnel service area as the research object,this paper applies the sponge city concept to the rainstorm control of the service area of expressway,constructs a low impact development system for service areas under the concept of sponge city.It provides an important reference for the promotion and application of the sponge city concept in the service area,enriches the design and evaluation system of the low impact development system in the service area,and provides a relatively complete solution for the construction of the highway sponge service area.