以盤剪方式改良砂土相對密度之研究

A Study on Plate shear to Improve Relative Density of Sand

楊佳勳(Chia-Shun Yang)

指導教授 ： 馮道偉

中原大學/工學院/土木工程研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200471

摘要

中文摘要
工程界不斷地在研究發展新的地盤改良工法，盤剪能提供一水平向剪力使得土壤顆粒造成側向的位移，對顆粒與顆粒間的緊密結合應有很大的幫助。
本研究的主要目的是探討盤轉剪力行為對土壤相對密度的影響情形，並藉由改變含水量、載重、土樣粒徑、初始相對密度及盤轉方式等不同條件，去探討各條件在盤剪作用下土壤相對密度的改變，並進一步探討盤剪所能改良的深度及相對密度隨各深度的改變情形，期能了解盤剪在地盤改良應用的可能性。
本研究利用可施加盤轉剪力並同時記錄扭力與沉陷的圓盤剪力儀，土樣環半徑為10 cm，土樣高度為10.5 cm，進行初始相對密度為30％及50％、載重為7 kPa~150 kPa、含水量為0％~10％的麥寮砂、越南砂、標準砂試樣單向及往復盤轉剪力試驗，並量取剪動面深度及分層測定各層相對密度，以得知所能到達的改良深度。
研究結果顯示，改良效果隨著載重增加及含水量減少而漸增，且麥寮砂約為越南砂及標準砂的兩倍，往復轉動約為單向轉動的兩倍；改良深度則隨載重的增大而越深，而最終相對密度受含水量、載重、土壤粒徑及盤轉方式所影響，而與初始相對密度無關。盤剪可高度提升試體之相對密度，對淺層土層之相對密度改良情形較佳，對深層土層相對密度之改良則較為有限。
在現地應用上，可修改能施加扭力及軸力的預壘樁施工機具來進行盤剪，假設扭矩為25 kN-m、軸向壓力為100 kPa、土壤摩擦角為 、圓盤半徑為55 cm時，改良深度可到達55 cm。

關鍵字

盤剪 ； 相對密度

並列摘要

英文摘要
Researching new methods continuously in engineering. Excepting to find the better ground improvement method having superior effects. Plate shear could provide the horizontal shear, and it causes grain of soil to displace aside. It should be helpful to combine grain closely.
The purpose of study is to probe into how the action of plate shear influences on the relative density of the soil. And by way of changing water content、normal stress、grain、initial relative density、method of plate shear to probe into the influence of each term on the changing of relative density of the soil after plate shear. Besides, they probe into how plate shear could improve the depth and how the relative density may change with different depth. Excepting to understand if plate shear is possible to put in situ.
According to the result of the study, plate shear could promote the relative density of the ground. But it is better to improve of low ground than of deep ground. The depth of improvement will increase with the normal stress. But finally, the relative density will be influence by water content、normal stress、grain、initial relative density、method of plate shear, having no relationship with the initial relative density.

並列關鍵字

plate shear ； relative densit

參考文獻

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