節瘤型土釘與灌漿釘之三維數值模擬

Three-dimensional numerical analysis of knotted and grouted-soil nails

曹祖文(Tsu-Wen Tsao)

指導教授 ： 洪勇善

淡江大學/工學院/土木工程學系碩士班/碩士(2021年)

https://doi.org/10.6846/TKU.2021.00189

摘要

本研究主要以三維數值分析方法分別建立傳統灌漿釘、螺桿釘與節瘤釘拉出數值模型，與實驗室拉出試驗結果進行比較，並探究土釘於拉出期間周圍土壤所發展的漸進式破壞機制與應力影響範圍。
分析結果得知：(1)傳統灌漿釘數值模擬拉出力與實驗室拉出結果十分貼近，傳統灌漿釘不同釘徑其周圍土壤發展之漸進式破壞行為相似，由釘尾處的土壤開始產生解壓破壞，之後是土釘兩側之釘土界面與土壤發生剪力破壞，接下來釘土界面破壞逐漸發展到土釘頂部以及底部；當土釘拉出力達到尖峰值，緊鄰土釘頂部以及底部的土壤元素發生剪力破壞，破壞的趨勢由釘尾往釘頭發展，釘尾處的破壞區域約為0.5倍的灌漿釘直徑（2）螺桿釘周圍土壤破壞機制，是由釘尾和緊鄰釘身幾處的土壤開始產生破壞，之後再由釘身週圍慢慢擴大破壞區，最後相連完成破壞。當拉出力達尖峰值時，釘尾處的破壞區域約為2倍螺桿釘直徑。（3）節瘤直徑80 mm之節瘤釘周圍土壤的破壞過程為，尾端土壤元素開始產生解壓破壞，之後沿著節瘤表面逐漸向外擴張形成球狀剪力帶，隨拉出位移增加，節瘤前方土壤剪力破壞區域分別往前與往外漸增約1.7倍節瘤直徑。（4）雙節瘤間距240 mm之土釘拉出力會比節瘤間距80 mm來的大，拉出位移10 mm時，節瘤間距240 mm之土釘相較於節瘤間距80 mm，拉出力提升了12%。

關鍵字

三維分析 ； 土釘 ； 節瘤 ； 數值模擬 ； 周圍土壤之漸進式破壞行為

並列摘要

In this research, three-dimensional numerical analysis methods were used to establish the numerical models of grouted,knotted and screw-soil nails. Compared with laboratory pull-out test results, it also explores the progressive failure mechanism and stress influence scope of soil nails during the pull-out period.
The analysis results show that:
(1) The pullout force of grouted nails is very close to the pullout result in the laboratory. Grouted nails with different nail diameters have similar progressive failure behavior to the soil development around the nails.
(2) The soil failure mechanism around the screw nail is begin from the soil behind the nail tail and nail body and then gradually expands the failure area ,finally connects to complete the destruction,when the pull-out force reaches the peak value,the failure area at the nail tail is about 2 times the diameter of the screw nail.
(3) The progressive failure behavior of single knot nails with the knot diameter of 80 mm is begin from the soil behind the nail tail, when the pull-out displacement is 10 mm, The soil shear failure area in front of the knot gradually increases about 1.7 times the the diameter of the knot.
(4) When the pull-out displacement is 10 mm,the pull-out force of the soil nails with the knots spacing 240 mm is increased by 12% compared to the knots spacing 80 mm.

並列關鍵字

three dimensional simulation ； soil nail ； knotted ； numerical analysis ； progressive failure

參考文獻

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