Safety Evaluations of Ecological Levee using Numerical Method-A Case Study on Sinsing Levee

• Main Authors: Wei-Jen Chen, 陳韡臻
• Other Authors: Chih-Wei Lu
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/85075521695017922103

碩士 === 國立高雄第一科技大學 === 營建工程所 === 96 === This paper first collected the geography and geological conditions, hydrologic information of the studied site of Beinan River, and also the design drawing of the levee and also investigated vegetation root conditions in this levee by digging out and finally conducted tension tests of the roots. Then this paper used the continuous deformation finite element method analysis, PLAXIS, to analyze the ecological levee. Before a numerical code was directly applied on the levee simulation, sensitive analysis of each element which composed of the numerical model was discussed each by each. It can be stated as followings; (1) Triaxial Test was firstly carried out for understanding stress- strain behavior of soils at drained and undrained conditions. Also both a simpler soil model, Mohr- Coulomb, and a more sophisticated soil model, Hardening Soil model (HS model) were used. (2) Rapid drawdown of water level maybe causes disequilibrium earth pressure and water pressure between soils inside the levee and at river. Therefore the author used C-ψ reduction method to find out safety factors of slope stability of the levee regarding to various drawdown rate. (3) Ecological levee would surfer seepage failure at stream bank. Therefore another assumed case was related to an excavation induced seepage failure. It found out different hydraulic head losses would cause seepage exit at different location with different shape of failure zone in different soil conditions. (4) Grew vegetation stake could provide stability. The author used the numerical simulation on rectangular direct shear test of samples with soils and roots. After changing the 3 dimensional roots into two dimensional for PLAXIS simulation, the author found out roots provided reinforced result and this simulation result fitted with the experimental one. After detailed understandings of the important parameter effects of PLAXIS, more discussion of safety factor change before and after the ecological method was applied on the Sinsing levee, various water table conditions at two sides of the Sinsing levee was analyzed and evaluated.