模糊層級分析法應用於高雄地區深開挖擋土工法之評選

Selection of Deep Excavation Methods Using Fuzzy Hierarchy Analytic Process

深開挖施工易發生人員傷亡、工期延誤與成本增加的重大損失，故安全性為深開挖施工評選適當深開挖工法的首要考量因子。然而，除了安全性外，其他如工期、成本與品質亦為重要的工法評選因素而須予以納入考量。欲避免或降低開挖工程失敗之風險，首要工作在於正確地評選最適於工程所在地之工法。然而，由於評選的因子（準則）繁多，使得選擇工法的過程具有高度的複雜性與不確定性，而難以正確地選擇最適的工法。本文提出模糊層級分析法(FAHP)，將工法評選的複雜過程予以系統化，以期協助規劃人員能正確地評選適當的工法。此分析法藉由因子（準則）間相對重要度的問卷結果，可針對在不同資訊掌握度下（α值）評估各準則間之相對權重。最後，本文以高雄地區之四種常用之深開挖工法（包括地下連續壁工法、鋼版樁工法、預壘排樁工法與主樁橫板條工法）之評選為案例，來說明此模式的分析程序，並以Buckley所提之FAHP法進行比較，其結果驗證了本模式之準確性與有效性。

Deep excavation operations of building foundations often cause construction accidents that bring about substantial fatalities or injuries of workers, competition delay and cost overrun, thus safety is a primary consideration in selecting an appropriate construction alternative among the deep foundation excavation methods. Although safety is the most important criteria, other important decision criteria such as cost, duration, and quality of the construction task also need to be considered in the process of selecting an optimal excavation method. To effectively avoid or reduce failure risk, the primary task is to accurately plan and determine the most appropriate deep excavation method for the associated site environment. However, the process for determining the most suitable alternative contains a great deal of complexity and uncertainty due to numerous decision factors or criteria, so that it is difficult to correctly make a right decision. This paper presents a fuzzy analytical hierarchy process (Fuzzy AHP) which can be used to systematize the complex evaluation process so as to assist project planners towards an accurate method decision. This model is capable of dealing with uncertainties regarding the varied degrees of believe (α value) and analyzing relative weights among criteria from questionnaires. Finally, a case study for selecting the most suitable alternative among the most commonly used deep excavation methods including Slurry-wall method, Sheet pile method, Boring piles method and Guide pile method in Kaohsiung area, is presented to illustrate the procedure of this model, and to demonstrate its accuracy and effectiveness by comparing the results of the model with those of Buckley’s FAHP. The comparison results validate the accuracy and effectiveness of the model.