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為了深入瞭解垂直載重基樁在砂土中之力學行為，本研究以有限差分法程
式一FLAC為分析工具，冀期探討基樁之Q-S曲線、Q-D曲線、t-z曲線、q-z
曲線及樁身摩擦力曲線等之關係，並與試驗數據加以比較。本研究莫爾─
庫倫土壤模式之分析成果顯示(1) 基樁邊界影響的範圍在底部約為 4倍樁
徑，側邊約為16而倍樁徑。軸對稱模式較平面模式之分析成果較正確
。(2) 基樁之包松比ν值對基樁整體力學行影響不大。在樁頭沈陷量小於
直徑之十分之一範圍內，遵守上述規則時可以FLAC程式精確預測樁徑和長
度之基樁之力學行為。但樁與沈陷量大於直徑之十分之一時，本分析模式
會略為低估沉陷量。
In order to understand the stress behavior of vertically loaded
piles in sand, the study used a finite difference program-FLAC
as a tool to write the analysis program. The Q-S curve, Q-D
curve t-z curve, q-z curve as well as f-D curve were studied
and were compar edwith the test results. By using the Mohr-
Coulomb model for soil elements, it is found that the square
element is the best for these cases, and the assymetric model
is bettr than the plain model. The boundary effect distances
are then four times of pile diameter from the bottom of the
pile tip and sixteen times of pile diameter form the side of
the shaft. The Poesson''s fatio of pile shaft has little
influence on the stress behavior of piles. Once using FLAC and
following the rules describde above, one can prdeict the stress
behavior of piles with any size of diameter and length in sand
when the settlement of the pile top is less than ten percent of
the pile diameter. However, the estimation fo pile top
settlement will be a little bit conservative when it is larger
than ten percent of the pile diameter.
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