Design Management And Scheme Evaluation Of Utility Tunnel On EPC Contracting Mode

The utility tunnel is a form of municipal projects actively promoted in China in recent years.It has many advantages such as high degree of intensification,economizing on underground space and facilitating the unified management of municipal pipelines.Meanwhile,it can reduce the repeated excavations resulted from pipeline maintenance or re-construction.The social benefits brought by the utility tunnel are significant.However,the benefits are not so significant as expected from the feedback of different parties involved in the construction of utility tunnels.The main reasons are as follows: because of the high requirements of function and quality of the utility tunnel projects,the technology of construction is difficult.At the same time,it is easily affected by the change of construction environments and the irrational design scheme,resulting in the increase of the project cost.Therefore,for a construction contractor,the increase of the design change will also lead to the increase of the construction cost,finally making the profit of project difficult to be guaranteed.At present,more and more utility tunnel projects are adopting EPC contracting mode,which can effectively reduce the increase of cost caused by the gap between design and construction.The contractor has rich experience of construction technology,and it also has the independent design right.Now the enterprises that intend to participate in the construction of the utility tunnel are trying to find out how to carry out the effective design management and predict the possible risks of the increase of cost caused by the change of design scheme in advance.They would like to strengthen the integration of design and construction in the early stage of the design phase to achieve the function value and maximize the profit of the utility tunnel projects.This paper focuses on the utility tunnel projects that adopt the EPC contracting mode.Firstly,the paper analyzes and summarizes the factors and cost control measures that influence the cost of utility tunnel project and the increase of construction cost.The author finds that strengthening the management of design phase can effectively reduce the risk of increase of cost.In consideration of the huge impact of design phase on the cost of project,the author uses Delphi method and Analytic Hierarchy Process to study and summarize a set of evaluation index system and evaluation process targeted at the design scheme of the utility tunnel.The design scheme is evaluated from six dimensions:the rationality of the horizontal and vertical layout,the rationality of the structure design of the utility tunnel,the function of the auxiliary system,the safety of the utility tunnel,the applicability of the building method and construction technology,and the risk degree of cost control.The subitem indexes and weights are set from above six dimensions to evaluate the design scheme.Then the evaluation on different schemes of design are carried out by the form of experts scoring.The corresponding improvements are made at last.This paper takes the section E of the utility tunnel project of No.C road in someplace as an example.According to the above mentioned advice,the paper analyzes and evaluates the scheme of design of this project including the horizontal and vertical layout,the design of the cross section,structure and waterproof,treatment of earthwork and foundation and auxiliary engineering system of this project.Then on the basis of the results of the experts’ scoring,the optimization points of original project are found out and the corresponding optimizations are made later.At last,the evaluation result of the final scheme is excellent.Through the analysis of the actual construction conditions and cost of the project,the paper shows that the construction drawings of the project are consistent with the design scheme as a whole.The construction process is smooth and the expected benefits are good.It shows that the evaluation index system of the scheme is effective.This method has certain value of application and promotion.