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  • 學位論文

往復盤轉改良砂土密度之室內實驗研究

An Experimental Study of Reversal Disc Shearing for Sand Density Improvement

指導教授 : 馮道偉

摘要


盤轉工法係以利用圓盤施加一垂直正向應力和水平向之盤剪應力於疏鬆砂土之水平表面,可使得砂土顆粒發生側向位移,使得顆粒排列更為緊密,也因而提高相對密度。 本研究以麥寮砂與渥太華砂及各混合10%細白雲母(通過#325)四種不同顆粒特性之砂土為土樣,試驗土槽內徑為600 mm,盤轉圓盤直徑分為150 mm,土樣厚度為75 mm,土樣初始相對密度為35 %。試驗中施加靜壓載重11~42 kPa,盤剪單位轉角為5°和15°,藉由施加靜壓載重和圓盤轉動使試體壓縮,進而量測圓盤沉陷量。之後於試體中心位置進行靜壓載重試驗來評估改良成果。 試驗結果顯示,相對密度改變量隨靜壓載重增加而增加,且改良效果與砂土顆粒特性有關。在11 kPa的圓盤靜壓加載後,渥太華標準砂比麥寮砂的相對密度約高了3 ~ 4%,可能的原因是渥太華標準砂粒徑較大且呈現次圓狀,具較低之最大孔隙比,因而些微的壓縮量會造成較大的相對密度增加;麥寮砂及渥太華標準砂試體經由圓盤靜壓及盤轉後,麥寮砂比渥太華標準砂的相對密度約高了3~4%,可能的原因是麥寮砂顆粒較小且形狀多為板狀,具較高之最大孔隙比經過盤轉後顆粒重新排列之程度較高,使得相對密度增加較多。渥太華標準砂與麥寮砂各混合細白雲母時,靜壓與盤轉的結果皆比未加細白雲母時相對密度還要低,可能的原因是細白雲母添加後造成麥寮砂與渥太華標準砂的最大孔隙比變大與最小孔隙比變小而造成相對密度變低。若以砂土相對密度75%以為最低門檻,麥寮砂及渥太華標準砂及各混合10%細白雲母在11~42 kPa靜壓改良後的相對密度皆不合格,而在11~42 kPa盤轉改良後相對密度皆在75%以上,且在42 kPa的壓力下都高達95%以上,效果可以說是頗佳。

關鍵字

相對密度 變形模數 盤轉

並列摘要


Disc Shearing construction method based on the use of a vertical disc applied normal stress and shear stress horizontal to the disc on a horizontal surface of loose sand, sand particles can make lateral displacement occurs, so that the particles are arranged more closely, and thus also improve the relative density. In this study, there are four different particle characteristics of soil samples which are MaiLiao sand, Ottawa sand, MaiLiao sand mixed with 10% of Musco fine sand and Ottawa mixed with 10% of Musco fine sand. The inner diameter of bin is 600 mm and the Disc Shearing is 150 mm, the thickness of soil samples is 75 mm, the relative density of the initial soil was 35%. In this test will apply a static loading of 11 ~ 42 kPa, the angles of Disc Shearing will be 5 ° and 15 °. To measure the amount of Disc settlement by applying a static load and rotate so that the specimen disc compression,. After the above test, we will make another static loading test which specimens will be in the center to investigate and improve the effect of soil density Disc Shearing. The test results showed that the change in the relative density increases with static load, but the effect will be improvement due to the different characteristics of sand particles. Under static load of 11 kPa, the relative density of Ottawa standard sand is higher than Mailiao sand about 3-4%, possibly because of the Ottawa standard sand is larger and showed sub-rounded, with a lower Maximum Void Ratio thus a slight of compression will cause to the amount of increase in the relative density; After the disk static and disc shearing, the relative density of Mailiao sand higher than the Ottawa standard sand about 3-4%, the possible reason is that the particles of Mailiao sand is smaller and most of its shape look like a plate, the re-arrange degree of Mailiao sand is higher after the Disc Shearing, so that the relative density increased considerably. Ottawa standard sand and Mailiao sand mixed with fine Musco separately, the results of the static pressure and disc shearing showed that the relative density are lower, the possible reason is to add 10% of fine Musco sand. The lower relative density which may caused from the differences of Maxmum and MinmumVoid Ratio.

參考文獻


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被引用紀錄


林子傑(2017)。飽和疏鬆砂土盤轉改良效果之研究〔碩士論文,中原大學〕。華藝線上圖書館。https://doi.org/10.6840%2fcycu201700620
詹皓然(2015)。轉盤粗糙度影響砂土盤剪行為之實驗研究〔碩士論文,中原大學〕。華藝線上圖書館。https://doi.org/10.6840%2fcycu201500730

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