本文以PFC3D（Particle Flow in 3 Dimension）及FracMan建立正交性合成岩體（synthetic rock mass, SRM）之模擬技術，並探討不同裂隙程度（P32）、取樣體積、裂隙直徑（D）及費雪常數（κ）對正交性岩體力學性質及其變異性之影響。本文亦針對類橫向等向性岩體進行相關模擬，並與前人研究之橫向等向性岩體進行比較。透過一系列SRM模擬結果顯示：裂隙程度、取樣體積、裂隙直徑及費雪常數皆對岩體力學性質及其變異性有所影響。隨著岩體裂隙程度、裂隙直徑增加，其正規化力學性質將降低，力學性質變異係數則隨之增加。岩體力學性質變異係數（CV）與取樣體積開根號成反比，並遵守中央極限定理。費雪常數增加，岩體之正規化力學性質平均值將隨之上升，變異係數則隨之下降，岩體行為逐漸由等向性轉為異向性。最後，本文以數值模擬獲得正交性合成岩體之應力應變組成律，其組成律柔度矩陣（compliance matrix）符合Amadei （1987）之正定性（positive definite）檢核。

This paper uses Particle Flow in 3 Dimension (PFC3D) and FracMan to establish a simulation program of synthetic rock mass (SRM) for orthotropic cases. Besides, this paper discusses the effects of fracture intensity (P32), sampling volume, fracture diameter (D) and Fisher constant (κ) on the mechanical properties and the variation of orthotropic rock mass. In addition, this paper conducts numerical simulations for transversely isotropic rock mass and compares them with previous research results. Based on the SRM numerical simulation results, the fracture intensity, sampling volume, fracture diameter and Fisher constant all have strong effects on the mechanical properties and variation of rock mass. The normalized mechanical properties of rock mass decrease with the increase of fracture intensity and fracture diameter. Conversely, the variation increase with the increase of fracture intensity and fracture diameter. In addition, the coefficient of variations (CV) of mechanical properties of rock mass are inversely proportional to the squared root of sampling volume, which conforms the central limit theorem. As the Fisher constant increases, the mean value of the normalized mechanical properties of rock mass will increase, the coefficient of variation will decrease, and the rock mass behavior will gradually change from isotropic to anisotropic. Finally, the composition law of orthotropic rock mass via conducting a series of numerical tests, and the compliance matrix was validated with the positive definite of Amadei (1987).

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