盤轉影響砂土相對密度之研究

An experimental study on the effect of disc shearing on the relative density of sands

李尚杰(Shang-Jie Li)

指導教授 ： 馮道偉

中原大學/工學院/土木工程研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100943

摘要

摘 要

盤剪工法係以圓盤施加一正向應力於砂土，再轉動圓盤以施加水平剪力，可使砂土顆粒產生側向位移而錯動，促使砂土顆粒間結合更為緊密，進而提高砂土強度。
本研究以麥寮砂及渥太華砂二種不同顆粒特性之砂土為土樣，試驗土槽內徑為600 ㎜，盤剪圓盤直徑分為150 ㎜和200 ㎜，土樣厚度為150 ㎜，土樣初始相對密度為50 %。試驗中施加靜壓載重10~90 kPa，盤剪單位轉角為5°和15°，紀錄圓盤沉陷量和土樣表面隆起量，並進相對密度試驗，以推估影響效果。
試驗結果顯示，相對密度改變量隨靜壓載重增加而增加，但過大靜壓會產生承載力破壞而使砂面隆起，且相對密度變低；於承載力破壞前進行盤轉，改良效果明顯。麥寮砂和渥太華砂試體在靜壓後盤轉，於深度50 ㎜、90 ㎜和130㎜處，往復式盤轉較單向式盤轉效果佳。在承載力破壞前的靜壓和盤轉下，直徑200 ㎜圓盤相對密度改良效果優於直徑150 ㎜圓盤，且直徑200 ㎜圓盤影響區域和引響深度都優於直徑150 ㎜圓盤。麥寮砂靜壓時相對密度最大可提升10%左右，盤轉相對密度可再提升5%左右，渥太華砂靜壓時相對密度最大可提升15%，盤轉相對密度可再提升5%左右；另外進行四點盤轉試驗，麥寮砂相對密度最大提升20%左右，渥太華砂相對密度最大提升28%左右。

關鍵字

盤剪 ； 相對密度 ； 細料含量

並列摘要

Abstract
Disc shearing induces a normal stress and a horizontal shear force on the sand samples. This may produce lateral displacement of sand particles to enhance the sand strength and make the sand grains closely packed.
In this study, Mailiao sand and Ottawa sand are used as soil samples to include two different grain characteristics. The inside diameter of the test tank is 600 ㎜, the diameter of the shearing disc is 150㎜or 200㎜, the height of the soil sample is 150 ㎜, and the initial relative density of the soil sample is 50%. The normal stress varies from 10 to 90 kPa, the shearing unit angle varies from 5 to 15 . The disc settlement, the amount of sand surface heave, and the relative density are observed.
The results show that relative density of sand increases with increasing normal stress and is a function of grain characteristics. But too much load will induce a bearing failure. Reversal disc shearing is better than one-way disc shearing in depth 50 ㎜、90 ㎜、130㎜ with Mailiao sand and Ottawa sand.
Disc shearing with 200㎜ diameter relative density better than the 150㎜ diameter disc improver disc,and the 200㎜ diameter disc induce greater gone of influence than the 150㎜ diameter disc. Under static load,the relative density of Mailiao sand increase by up to 10% and disc rotation increases the relative density by 5% the most. For Ottawa sand, static load increases the relative density by up to 15% and disc rotation increases the relative density also by 5% the most.
When disc shearing is executed at four points , the relative density of Mailiao sand sample increases by up to 20%, whereas for Ottawa sand sample by up to 25%.

並列關鍵字

Plate Shearing ； relative density ； Sands with Fines

參考文獻

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