粉質砂土中傾斜2*2陣列式群錨之受力行為

Anchorage Behavior of Inclined 2*2 Arrayed Anchors in Silty Sand

游姍儒(SHAN-RU YU)

指導教授 ： 許世宗

朝陽科技大學/理工學院/營建工程系/碩士(2018年)

摘要

本文採用數值分析方法來探討粉質砂土中傾斜2*2陣列式群錨之錨碇行為，再以現地試驗驗證數值分析的正確性。現地試驗位於鹿港彰濱工業區，數值分析是使用SHASOVOD模式(A Strain Hardening-Softening and Volumetric Dilatancy Model)進行分析。數值結果顯示，數值分析結果與現地試驗的結果一致。

當間距為4D (D為地錨直徑)時，群錨效益係數為88%，地錨周圍土壤的降伏區會產生重疊。當間距為10D時，群錨效益係數為99%，群錨中的每支地錨行為也接近於單錨的行為。

因為竹北某建設公司背拉支撐系統設計錯誤導致工安意外，所以本文研究了最小覆土深度及最小自由段長度。為了避免地錨降伏範圍可能會發展至地表與擋土壁體，本研究建議地錨最小覆土深度Hmin應大於2m，最小自由段長度Zmin應大於2m。

關鍵字

數值分析 ； 粉質砂土 ； 2*2陣列式群錨 ； 群錨效益係數

並列摘要

This study adopts the numerical method to investigate the anchorage behavior of 2*2 arrayed anchors in silty sand. The numerical results are verified by in-situ results. The field anchor tests are conducted at Jhangbin Industrial Park in Lukang, Changhua. A strain hardening-softening and volumetric expansion model (SHASOVOD) is carried out to perform the numerical analysis. The numerical results reveals that the numerical analyzed results are consistent with in-situ test.

When the spacing between neighboring anchors is 4D (where D is the anchor diameter), the efficiency of an anchor group is approximately 88%. The yielding zones of soil around the anchors are highly superposed. When the spacing is 10D, the efficiency of anchor groups is about 99%; the behavior of each anchor in the anchor group is similar to the behavior of a single anchor.

Because the inaccurate design of tieback system in deep excavation in Zhubei City which constructed by a certain company had induced site disaster. For avoiding the yielding zone of anchor develops to ground surface and diaphragm wall, this study suggested that the overburden depth and free length all exceed 2m.

並列關鍵字

Numerical analysis ； Silty sand ； 2*2 arrayed anchors ； Efficiency of anchor groups

參考文獻

1. 許世宗，「以現場足尺寸試驗和全非線性三維數值分析探討陣列式傾斜群錨互制行為與地錨設計規範之挑戰」，國科會計畫，台中，2018。

2. British Standards Institute (BSI), British Standard Code of Practice for Ground Anchorages, England, 1989.

3. S. T. Hsu, “A Constitutive Model for the Uplift Behavior of Anchors in Cohesionless Soils” Journal of the Chinese Institute of Engineers, Vol. 28, No. 2, pp. 305~317, 2005.

4. 許世宗，「砂土中垂直地錨之錨碇行為」，國立台灣工業技術學院博士學位論文，台北，1995。

5. Itasca Consulting Group, Inc, FLAC3D：Fast Lagrangian Analysis of Continua in 3 Dimensions, Version 2.0, Vol. 1~4, Minnesota, 1997.