A Quick Evaluation Method for Impact Range of River Dredging

• Main Authors: Yang, Min-Ying, 楊旻穎
• Other Authors: Lu, Chih-Wei
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/w7qza3

碩士 === 國立高雄第一科技大學 === 營建工程系碩士專班 === 106 === Taiwan is located at the junction of the earth's crust. Large terrain changes lead to steep slopes in mountain rivers. River water flow rate is fast and plus over-development of topography. In the mountainous areas, whenever typhoons and heavy rains are encountered, a lot of topsoil loss and move to the lower part, even directly into the stream channel, blocking flood passages seriously affects river drainage capacity. There are often public and private property on both sides of the river. Therefore, it is necessary to maintain proper drainage capacity of the river. The purpose of the study is to discuss the influence of river/ stream dredge on the adjacent soil slope. The analysis program used herein is both STABL coded by the limit equilibrium concept and analysis program SEEP/W of GEOSTUDIO coded by the concept of finite element method. By these two different programs, the study aimed at establishing relationship between the different soil friction angles and the dredge width on safety factors under different periods of dredge. It is hoped to provide a reference for the preliminary safety evaluation of the slope or river/ stream channel as long as that is of a similar terrain with a similar demand. Findings of this study are: STABL and GEOSTUDIO present that in the same one stratum S_U and compound stratum G_U, G_DH (when the dredge surface does not coincide with the stratigraphic surface), the safety factor of the dredged slope filled with soils of friction angle 35 degree is reduced 3 to 4 times than that of 10 degree. In terms of a certain safety factor, the reaction speed of friction angle 35 degree soils is only 1/3 to 1/4 times to that of 10 degree. After comparing the quick evaluation method with the numerical analysis that is to conduct GEOSTUDIO program in the compound stratum (the dredge surface coincides with the stratigraphic surface) is consistent to each other in the actual case study. It showed that the proposed method can be used effectively for preliminary assessment. Last but not the least, this study established a relationship between the soil friction angle and the total dredge ratio within a specified safety factor, which can be used as a reference for the dredging width of the river channel in planning.