污水下水道系統已成為不可缺之公共建設，其功能已由傳統目標，逐漸轉變為多目標效益，不僅提升水資源再利用之可行性，且被先進國家列為評定都市環境重要指標之一，為現代化都市所必備之公共設施，具有提升生活文化及水環境美質之功能。 污水下水道分管網工程多採用小管推進工法，此種方法已被廣為運用且取代傳統明挖工法，污水下水道分管網工程之推進施工皆於地面下作業，若現地狀況不明確時，其所面臨之施工階段風險因素更是不可容忽視，應對其面臨之風險加以分析並管理風險，而施工風險因素造成之主要影響為「成本」及「進度」兩大部分。故於施工前詳加考量風險因素對進度及成本造成之影響，將是編列施工預算及工期時之考量依據。 本研究擬探求污水下水道分管網施工時可能遭遇的各種施工不確定性因素，並建立合適之風險量化評估模式與風險量化分析，希冀風險量化評估結果可做為編列施工預算及制定施工工期之參考依據，其做法為將各種影響因素對預算及工期造成之間接影響，反應到實際執行之預算及工期上，使實際之預算及工期趨於合理化。本研究經系統性歸納整理後，將施工不確定性因素分成五大主層面及十四項子層面影響因子，並藉本研究建立之量化評估模式，以專家問卷調查方式由工程主辦單位、工程顧問公司及專業營造廠商等對於風險因素之發生機率及衝擊影響損失之評估，並計算風險值以期作為後續相關研究之風險管理策略擬定參考依據。 The sewage system has become an indispensable public works. Its function has gradually evolved from its traditional goals to having multi-purpose benefits; it not only elevates the feasibility of water recycling, but is also listed by advanced countries as an important indicator of the urban environment. It is an indispensable public works in the modern city, and has the functions of elevating the culture of living and improving the water environmental aesthetic. Sewage pipe network engineering usually uses tunnel jacking construction method, which is widely used and replaced the traditional open cut dredging method. The pipe jacking construction of sewage pipe network engineering is all conducted underground. If on-site conditions are unclear, the risk factors upon construction cannot be overlooked. Such risks should be analyzed and managed. The main effects caused by construction risks are “cost” and “progress.” A detailed consideration of the influence of risk factors on progress and cost before construction would be a basis for evaluating the construction budget and the construction period. This study seeks to explore the various construction uncertainties while constructing a sewage pipe network, and establishes an appropriate risk quantification evaluation model and analysis, in hopes that the results of the risk quantification evaluation model can be used as a basis of reference upon establishing the construction budget and period. This method reflects the indirect effects caused on budget and construction period on the practically executed budget and construction period, so that the actual budget and construction period become reasonable. After systematic summarization and organization, this study divides construction uncertainty factors into five main aspects and fourteen sub-aspects of factors. It uses the quantification evaluation model established by this study in expert questionnaires for main sponsors of construction, engineering consulting firms, and professional construction companies to make assessments on the chances of occurrence of risk factors and impacts on losses, and calculates risk values as a reference basis for future studies relating to risk management strategies.
