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    Please use this identifier to cite or link to this item: https://tkuir.lib.tku.edu.tw/dspace/handle/987654321/74496

    Title: 山谷崩坍模擬堆積體之顆粒分佈與孔隙率
    Other Titles: Study on the grain distribution and porosity of landslide mass in a valley model
    Authors: 鄧芸浩;Dung, Yun-Haw
    Contributors: 淡江大學土木工程學系碩士班
    Keywords: 天然壩;Landslide dams;堆積體;顆粒分佈;谷型;孔隙率;Mass;Grain distribution;Valley;Porosity
    Date: 2011
    Issue Date: 2011-12-28 18:44:45 (UTC+8)
    Abstract: 堰塞湖的壽命及壩體潰決方式與崩塌堵江之岩屑或土砂的材料特性有關,如壩體透水係數與壩體強度,而天然壩體的強度及透水性則與其組成壩材之顆粒分佈有密切相關性。由文獻可知:天然壩體的組成顆粒大小變化範圍極大,且天然壩體上部常具一粗顆粒或碎石組成的外殼,底部組成顆粒卻是極細小,故天然壩體各部位力學性質是不均質,其顆粒大小成分及堆疊排列方式有關。
    The lifetime and dam breach modes of landslide dams are related to the material characteristics of the rock debris or the sediment which collapsed to block rivers, for example, the permeability coefficient of the dam and dam strength, and the strength of natural dam and their permeability are closely related to particle distribution of the dam material composition. According to literature, the particle sizes of dam material composition vary greatly, and the upper part of natural dams often contains a shell made of coarse particles and gravels, the bottom is composed of very fine particles. Thus, the mechanical properties of various parts of natural dams are not uniform, they are related to particle sizes, composition and mode of stacking and arrangement.
    This research used the v-shaped slope apparatus to simulate the valley terrain. Tests of slope collapse accumulations were carried out through changing the various influencing factors such as particle sizes, slope, and distances. The accumulations were treated with solidification. Blocks of materials were removed to take photos to build a profile for imaging analysis. Finally, a test of mechanics was performed on the accumulations.
    The following conclusions have been obtained through the research results: (1) The angle of repose did not show a significant difference due to different testing methods, the angle of repose became more gradually fixed after the particles exceeded a certain count. The shape of valley bottom does not affect the naturally stabilized angle of repose to maintain the final landslide mass. (2) In a valley landslide process, after the particles fell to the valley bottom, they often hit the other side and bounced back to cover the landslide lass or mixed with the particles that came down later. Because the natural landslide mass formed went through the dynamic compaction effect, its slope stability is higher than its static angle of repose. The primary factors in order of significance that affect the slopes of landslide mass were long drop distance, steep slope, and coarse particles. (3) The porosity of landslide mass reduced slightly as the sliding distance increased, the higher the fine particle count the lower the porosity. In addition, it was found out through imaging analysis and sieve analysis that the coarse particles of landslide mass were mostly located in the upper layer, and the fine particles in the lower layer. The distribution of coarse and fine particles became more uniform as the sliding distance increased. (4) The porosities differed between the upper and lower layers in the landslide mass. When applied in the analysis of permeability of natural dams, it differed from the traditional single permeability coefficient, the correction made to the calculation of seepage volume due to the upper and lower permeability coefficients caused a somewhat different result from the traditional single seepage volume. This can be used as a reference to estimate the dam breach time in the future.
    Appears in Collections:[Graduate Institute & Department of Civil Engineering] Thesis

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