水岸堆積土砂邊坡之穩定性研究

Study of the Slope Stability of Deposition Sediment on the Waterfront

10.29417/JCSWC.201009_41(3).0004

陳晉琪(Jinn-Chyi Chen)；呂家豪(Jia-Hao Lu)

水岸破壞 ； 堆積土砂 ； 張力裂縫 ； 臨界關係式 ； riverbank instability ； deposition sediment ； tension crack ； critical stability equation

中華水土保持學報

41卷3期（2010 / 09 / 01）

231 - 242

繁體中文

本文透過理論與實驗，研究由堆積土砂所形成之水岸邊坡的穩定性。理論部份，以靜力學觀點，考量水岸邊坡中土層含水並形成張力裂縫，進而建立水岸發生平面破壞之臨界關係式。水岸破壞之臨界關係式與水深、土壤單位重、土壤凝聚力、土壤內摩擦角、張力裂縫深度及水岸幾何形狀（水岸高變與坡度）有關。依據此關係式，本文探討相對水深、水岸幾何形狀及張力裂縫深度等變化對水岸穩定條件的影響，並說明如何利用此臨界關係式來評估水岸是否發生破壞。實驗部份，觀察水岸在邊坡形狀改變與水位緩增下之破壞型態。研究結果顯示，水岸坡度增大、水深增加或裂縫深度增加時，會降低水岸之穩定性；理論所推算之水岸穩定條件並與實驗結果大致相符。

This study examines the stability mechanism of a riverbank formed from deposition sediment on the waterfront through theoretical and experimental analysis. In the theorem, a critical stability equation of the riverbank with tension crack under water level variation is developed based on the concept of statics. The critical equation of the riverbank stability depends on the water level, soil unit weight, soil cohesion, internal friction angle, and the shape of the riverbank (riverbank slope and riverbank height). Several factors influencing riverbank failure, including water level variation, riverbank height, riverbank slope, and tension crack, are also presented. In addition, the behaviors of riverbank failure under various cross sections of riverbank and water level variations are examined by experimental investigation. The analytical results show the instability of the riverbank increases with increasing riverbank slope, water levels, or tension cracks. The experimental results agree with the predictions of the critical equation proposed in this paper.