| With urbanization’s continuous advancement,the impermeable area of surface increases rapidly,which affects rainwater’s normal seepage.When the rainstorm occurred,traditional pipe network system’s drainage capacity is limited,and it will make nodes overflow.In order to avoid waterlogging,we can use storm-water management measures to increase the efficiency of infiltration and storage through reducing rainwater from the source,control runoff in the process and dispose rainwater in the end.It can also reduce runoff,recharge groundwater,improve natural water cycle and etc.This paper takes frequent flood disasters as background,carries out the transformation research of traditional rainwater pipe network system,Based on Fuzzy Analytic Hierarchy Process(FAHP),we choose the highest score of transformation plan,and carry out the research of construction site’s risk analysis.This paper’s main research work is as follows:Firstly,based on the concept of low impact development planning ideas and technical measures,this paper carries out the comprehensive theoretical study on all kinds of low impact development measures.It uses SWMM to simulate and experiments to research,analyzes low impact development measures’ effects from return periods,depth,vegetation density and slope.Research’s results show that runoff’s reduction rate decreases with return periods’ increase and increases with the increase of the other three.The comparison between experimental and simulated values shows that the change trend is the same,and the error is within 10%.Secondly,based on building site’s geographical location and climate characteristics,this paper carries out the research of rainwater pipe network’s reformation schemes.It analyzes different schemes’ hydrologic and hydraulic conditions under different return periods with SWMM.This paper studies fuzzy analytic hierarchy process’ s theoretical meaning and application steps,obtain different schemes’ final scores through weight and standardized value obtained by this method,and then select the best scheme.Research’s results show that the environmental index is 0.503,the weight of the economic index is 0.190,and the weight of the social index is 0.307.The low impact development scheme’s total score is 82.55,and the deep tunnel scheme’s total score is 65.4.Therefore,this paper selects the low impact development scheme.Finally,this paper summarizes rainwater pipe network system’s research progress at home and abroad,and it also introduces risk analysis’ s steps and methods.Based on the optimized transformation scheme,we simulate the hydrological and hydraulic conditions from system and nodes,and get system’s risk factors.This paper uses fuzzy comprehensive evaluation method to calculate different nodes’ risk coefficient and obtains risk evaluation matrix,so we can achieve the purpose of making risk research specific.Research’s results show that return period,rainfall peak coefficient and the rate of impermeable area are system’s risk factors.Factors’ risk matrix B=(0.135,0.788,0.865,0.226),the risk level is medium risk,and it is worth more attention in the later operation management. |
