本文以 PFC3D (Particle Flow Code in three dimensions)數值軟體進行裂隙
岩體之工程特性模擬，配合改變基礎長軸與不連續面位態之角度(α、γ)、
裂隙程度(P32)、裂隙直徑(D)、費雪常數(κ)等參數研究，進行岩石基礎承載
力異向性與變異性分析。
研究結果顯示上述參數對於裂隙岩體之承載力異向性與變異性有不同
程度影響。承載力變異性方面：(1) 承載力變異係數與傾角(α)具有倒 U 型
關係。(2) 承載力變異係數隨γ（基礎長軸與不連續面走向交角）增加而降
低，當γ=90 ﾟ時變異係數最低。(3) 裂隙程度、裂隙直徑越大，承載力變異
性越明顯。費雪常數越大，承載力隨α改變之變異性與異向性趨勢相反。而
在承載力異向性方面：(4) 裂隙程度、裂隙直徑、費雪常數越大，承載力異
向性越明顯。(5) 承載力隨傾角(α)具有 U 型關係，與單壓強度之異向性相
似。(6) 承載力隨α與γ而變動，而α的影響比γ顯著，且當γ=0 ﾟ時，承
載力最低，故以γ=0 ﾟ進行分析，可獲致偏保守側之承載力。(7) 基於數值
模擬結果，本文提出裂隙位態對基礎承載力分級之建議，可介接 RMR 分類
法針對岩石基礎之評分調整。

The research uses PFC3D (Particle Flow Code in three dimensions)
numerical software to simulate the engineering characteristics of fractured
rock masses, and introduces the discrete element method (Discrete Element
Method) using radial expansion from the Finite Element Method (Finite
Element Method) mesh size concept. Radial Expansion), used to quickly
check the characteristics of large-scale rock foundation engineering, with
orientation of discontinuities, fracture intensity (P32), diameter of
discontinuities (D), Fisher constant (κ) these parametric research and
analysis of the optimal orientation of the rock foundation.
Conclusions: (a) The greater anisotropy ratio, the greater difference
in strength between different orientation. (b) Both dip and dip-direction of
discontinuities have an anisotropic influence on the bearing capacity. (c)
When D and P32 increase, the bearing capacity decreases. (e) When the rate
of bond replacement is over 50% in simulation, the SRM will fail. (f) The
coefficient of variation will increase with greater D、 P32、κ, it presents
the uncertainty of the bearing capacity has the positive relationship with
anisotropy ratio(AR). (g) When the long axis of the foundation is
orthogonal to the strike of the discontinuity, the bearing capacity will
increase and the anisotropy will decrease compared to other orientation.

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