A System To Evaluate The Suitability Of Integrating A Water Supply Pipe Into The Utility Tunnel:from Research To Application

With the rapid urbanization in recent years,China has comprehensively promoted the construction of utility tunnels.By integrating the water supply pipes into the utility tunnel,we can save the space and improve the management of urban underground.However,when the pipe diameter gets large,a larger cross-sectional area of the utility tunnel is required,which demands high cost.Moreover,the accidental pipe bursting cases of water supply pipeline will result in the harmful influence and economic loss to the whole city.Hence,the technical and economic comparisons are essential before making a decision of whether integrate a water supply pipe into the utility tunnel,or not.From the previous studies,the effective evaluation methods are rarely reported.To solve this issue above,an evaluation system is proposed and applied to the real cases in this study,aiming at analyzing the suitability of integrating the water supply pipelines into the utility tunnels.The main contents are summarized as follows:Three primary aspects are analyzed for their effect to the suitability: safety,economy and social environment.Factors with significant influence for the suitability in each aspect are selected as the evaluation indexes.A hierarchical structure model is established using the Analytic Hierarchy Process(AHP).Based on the consulting reports from many experts,the weightings of different index were assigned,so that the evaluation system was constructed for the suitability of integrating the water supply pipe into the utility tunnels.For a specific case study,the weightings of index can be scored according to the actual circumstance.Finally,the evaluation result can be calculated.The evaluation grade can be divided into three levels:prior,suitable,and unsuitable.Three typical cases were selected from the pending construction projects of utility tunnels in a city at southern China,and the applications of the established evaluation system were analyzed..The result of the first example is “suitable”,and the other two are“unsuitable”.The reasons causing different results of the three examples are discussed by further analyzing the overall evaluation scores and detailed evaluation reports.The evaluation indexes can be divided into subjective and objective categories.The subjective indexes can be changed by technical means,and objective indexes cannot be changed by the objective or the environmental conditions.The evaluation result can be improved by optimizing those subjective indexes.In some cases,the evaluation result of“suitable” can be reached by increasing the weighting factors of objective indexes.The framework and outcome of this study provide a useful tool for the decision-makers in urban design and construction fields.