Research On Risk Management Of Utility Tunnel PPP Project Based On System Dynamics

In the process of urbanization,the supply and demand for municipal infrastructure is increasing,which is not matched with the current situation that the bearing capacity of existing municipal infrastructure is almost saturated.The government promotes the construction of comprehensive pipe gallery to enhance the supply capacity of municipal engineering related resources transportation system and enhance the comprehensive carrying capacity and safety guarantee capacity of modern cities.In China,the PPP project construction of the utility tunnel is in the initial stage,and the market rules,system standards and charging mechanism are not perfect.There are many problems in the practice of the pilot project,such as the lag of planning,the lack of upper legal basis for compulsory access to the corridor,and the difficulty of coordination among relevant subjects,which seriously affect the implementation and promotion of the PPP project of the utility tunnel.The key to the successful application of PPP mode in the construction of utility tunnel is to accurately identify and evaluate the potential risk factors of PPP project and formulate corresponding risk control measures.In this paper,the hierarchical holographic modeling method is used to build a multi perspective and multi-level risk identification model to identify the main risk factors of the utility tunnel PPP project,and screen out the risk factors outside the boundary to meet the requirements of system modeling.Secondly,according to the successful implementation elements of the PPP project,the risk system structure is analyzed,the system boundary is delimited,the causal loop diagram is drawn,and the system dynamics risk identification feedback model of the PPP project is obtained.Then,determine the variable types of each risk factor,draw the stock flow chart,comprehensively use G1 method and entropy method to calculate the combination weight,and weight the risk factors.Finally,the parameters are input into the dynamic equation to establish the system dynamics risk evaluation model of the utility tunnel PPP project.After debugging and improving,the model is applied to the project example.The Vensim software is used to simulate the risk value of each target risk changing with time,divide the risk level and judge the risk level,Taking the operation management risk with the largest cumulative value of risk at the end of franchise period as an example,the sensitivity analysis is carried out,and the corresponding control measures are put forward,and the implementation effect is verified by simulation.The simulation results show that the risk control measures can weaken the target risks to a certain extent.The study verified the applicability of system dynamics risk assessment model in the actual project,realized the risk cycle management of identification,evaluation and control,applied the risk management theory to the project management practice,and provided decision-making basis for all parties to participate in the PPP project operation.