Effect of the Anisotropy of the Layered Rock Mass on the Fracture Behaviours of Its Embedded Cracks

Abstract

The effect of anisotropy of the layered rock on the fracture behaviours of the embedded cracks is analyzed by using dual boundary element method. The layered rock foundation is modeled as transversely isotropic materials occupying semi-infinite extent. The anisotropy of the rock is expressed by ratio of elastic coefficients in directions perpendicular and parallel to the layer. By numerical calculation the effect of the anisotropy of elastic modulus, shear modulus and Poisson’s ratio of the rock on the SIF values of a single rectangular crack and the interaction between two coplanar cracks is obtained. The numerical results show that the SIF values for the crack tip parallel to the isotropic plane decrease with the decrease of the elastic modulus and shear modulus in a direction normal to the isotropic plane and those for the crack tip normal to the isotropic plane are contrary. The anisotropy of Poisson’s ratio has almost no effect on the SIF values and the interaction between the two coplanar cracks.

為探討層狀工程巖體在平行和垂直層面方向的各向異性對其中埋藏裂紋斷裂特性的影響,將層狀工程巖體地基模擬為半無限橫觀各向同性介質,用平行和垂直層面方向彈性系數的比值來表征該類巖體各向異性的程度,采用基于雙橫觀各向同性材料基本解的對偶邊界元方法,分析了該類巖體在平行和垂直層面方向上的彈性模量、剪切模量和泊松比的各向異性對正交于層面的單條矩形裂紋應力強度因子(SIF)和兩條裂紋間相互作用的影響規律。數值計算結果表明:平行層面方向的裂尖SIF值隨垂直層面方向的彈性模量和剪切模量的減小而減小,垂直層面方向的裂尖SIF值變化規律正好相反。泊松比的各向異性對裂尖SIF值和兩條裂紋間的相互作用均基本無影響。