港灣碼頭殘留水位之調查研究

Abstract

台灣中西部海岸高低潮差較大，高低潮漲落時，碼頭後線因基礎阻擋效果，常有殘留水位情況發生，造成殘留水壓及滲流力，使基礎土層發生流砂或管湧現象，危害碼頭安全，而目前一般碼頭設計，殘留水位的高度僅係依照經驗法則予以概估，對於殘留水位問題之研究實有其必要性，故本研究擬在已設碼頭後線實施殘留水位調查，利用觀測井現場觀測殘留水位之變化情形，及參考有關文獻所獲得資料，針對碼頭構造型式加以探討，繪出岸壁前後水位關係，探討影響殘留水位之因素及殘留水位之設計基準，並繪出流線網，計算殘留水壓及滲流力，分析殘留水位所產生之外力對碼頭設計之影響，研判是否發生管湧，危害到碼頭安全，以提出預防及改善之對策，並提出碼頭斷面修正設計，以供碼頭設計之參考。

As the fact shows that the tidal range in the mid-west coast of Taiwan is higher than that of the other coast. Each time, at ebb and flow, there usually ocoures residual water level produced by the resistance reaction from quay wall foundation in the back side area of wharf which causes residual water pressures and seepage forces and thus also generates quick sands and boiling affections against the foundation ot quay wall that would damage the safety of the wharf itself. According to current wharf designs, the elevation of residual water level has been estimated by experiences. Henceforth, the research purpose of this thesis was proposed to investigate the residual water level situation presented in the back side area of an established wharf. During this reaearch operation, observation well method was used to observe the variation of residual water level and it accompanled with a lot of references obtained for siudying various structure types of wharf. Tais research was planned to draw out a chart on the relevance of water elevation between the front and back sides of wharf quay wall which was provided for studying the influencing factors and the design criteria on residual water level. Neanwhile, a flow net was drawn for use in calculating the residual water pressures and seepage forces and it was also used for analysing the reaction forces initiated by residual water level in connection with wharf designs. By this research approach, it can help designer to study out the boiling situntion which may endanger the safety of wharf. For safety requirements, some preventive and improvement measures were proposed on the above mentioned problems. Additionally, in this thesis, corrective designs on wharf cross section were also provided for designer as references.