近年來公共工程大量需求興建，但公務預算卻逐年降低且用地取得愈來愈困難，為節省工程用地之費用及確保公共工程有效之施行下，使用河川公地並與堤防共構之機會愈來愈高，本研究以台灣電力公司嘉名～南科345KV輸電線路鐵塔沉箱基礎施工期間，堤防道路與前坡裂縫產生之案例，針對公共工程與堤防共構下施工期間堤防發生異狀，進行現場調查與試驗分析的方式對堤防共構後災害過程與原因進行探討。
實驗成果共指出，堤防與其他結構物共構施工時，採用沉箱基礎之施工方式，堤防彎道段與直線段均會造成堤防內地下水滲流之水力梯度上升，且彎道段之水力梯度值、地下滲流特性較直線段複雜，堤內側設擋土牆之區段更甚，使得彎道段施工之過程中，發生堤內沉陷形成空穴及堤防前坡之裂縫等異常現象與災害之機會增大，此項研究探討之結果，可作為日後堤防與其他結構物共構施工時應注意事項。對於人為施工所造成堤防災害的救災措施之研擬，本研究之緊急處理為現場實際實施所得之經驗，以曾文溪寮廍堤防於輸電線路鐵塔沉箱基礎施工期間發生災害為對象之實行成果證明，堤防災害的緊急處理可以防止災害擴大與減少後續復舊工程的難度。

In recent years, a great number of demands for public constructions have been claimed. Two things, however, make it difficult to fulfill the demands. One thing is that the official budget has gradually been reduced year by year, and the other is the acquisition of the land, which is quite unobtainable. To reduce the expenses spent on the land and to ensure that public constructions can be put into effect, many constructions are expected to be built on the common land as an appropriate site, which would be even better if it is combined with the bank.
This paper aims to analyze, under the condition of a combination of caisson foundation and bank structure, the field investigations and the experiments conducted at the Jarmin~ Nancole 345KV pylon of Taiwan power company, where cracks are found between the road upon the bank and the front incline.
The results indicate that, as the bank and other structures are combined together with caisson foundation, the hydraulic gradient of groundwater seepage tends to go up either on curved zones or straight zones. In addition, the conditions of hydraulic gradient and groundwater seepage are much more complicated on curved zones than those on straight zones, especially on those where there are retaining walls inside the bank. As a result, the situations mentioned above cause cavities and cracks in the bank slope. This study can provide the guidance of constructions based on the combination of the structure and the bank. In redacting the expedients to reduce the harm done to the bank by artificial constructions, the field work done at Laokwo bank on Tseng-Wen River is used as the example. The work proves that the expedient can prevent the disaster from worsening and help lower the difficulty of the following restoring works.

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