沉泥質砂土中傾斜摩擦型雙錨之受力行為

A Study on the Dual-Inclined-Friction Anchors in Silty Sand

顏明弘(MING-HONG YAN)

指導教授 ： 許世宗

朝陽科技大學/理工學院/營建工程系/碩士(2013年)

摘要

本研究利用數值分析與現地試驗的方式探討傾斜摩擦型單錨與雙錨之受力行為。數值分析的方式係利用三軸試驗結果，套用SHASOVOD模式(A Continuous Strain Hardening Softening and Volumetric Dilation Model)的架構

，求取該模式所需之參數，再利用數值分析軟體FLAC3D進行單錨與雙錨之受力行為分析。並以現場地錨試驗結果驗證數值分析之正確性，再進行各項地錨影響參數之研究，以瞭解傾斜摩擦型雙錨之錨碇行為。

由數值分析發現，對於傾斜摩擦型雙錨，水平間距Sh=4D (D：地錨直徑)時，群錨效益係數僅約80%，顯示其受群錨效應影響較大；但水平間距大於8D後，群錨效益係數達95%。群錨效應隨覆土深度增加而略為減少。由傾斜摩擦型雙錨發現，無論是改變覆土深度或是自由段長度，當水平間距Sh大於10D時，大致可忽略群錨效應對錨碇力之影響。無論是增加自由段深度或覆土深度皆可提升地錨之錨碇力，其中以增加覆土深度來提升錨碇力之效果為最佳。

關鍵字

數值分析 ； 三向度分析 ； 群錨效應 ； 沉泥質砂 ； 傾斜摩擦型雙錨

並列摘要

To evaluate the uplift behavior of single- and dual-inclined-friction anchors installed in silty sand, a series of triaxial test results were utilized to obtain the parameters of a continuous strain hardening-softening and volumetric dilation model, SHASOVOD. In conjunction with FLAC3D, a numerical study was carried out to analyze the behavior of vertically pulled out behavior of inclined friction single anchor and dual anchors in silty sand. A field test program was conducted in silty sand within an excavating site to verify the applicability of the numerical program. Finally, parametric studies on the factors affecting the anchorage behavior were executed.

According to the numerical results, when the dual-inclined-friction anchor installed in silty sand with a spacing Sh of 4D (D is the anchor diameter), efficiency of the anchor group was calculated to be approximately 78%~ 80%. As the Sh equals 8D, the efficiency of an anchor group exceeds 95%. The interference of a dual anchors decreases with an increase in overburden depth. However, interference almost can be eliminated as the anchor spacing exceeds 10D. Either embedded depth or overburden depth of an anchor increase, the anchorage capacity also increase. Increasing overburden is more efficient on increasing the anchorage capacity.

並列關鍵字

Numerical analysis ； Three-dimensional analysis ； Efficiency of an anchor group ； Dual-Inclined friction anchors ； Silty sand

參考文獻

4.許世宗和郭芷伶「沈泥質砂土中錐形擴座地錨錨碇行為之影響參數研究」，朝陽學報，第六期，第375-401頁，2001。

3.Hsu, S. T., “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.

11.Littlejohn, G. S., “Design Estimation of the Ultimate Load-holding Capacity of Ground Anchors.” Ground Engineering, Vol. 13, No. 8, pp. 25~39, 1980.

14.Thorne, C. P. “Penetration and Load Capacity of Marine Drag Anchors in Soft Clay., ” Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 124, No. 10, pp. 945~953, 1998.

15.Littlejohn, G. S., “Design Estimation of the Ultimate Load-holding Capacity of Ground Anchors.” Ground Engineering, Vol. 13, No. 8, pp.