双孔洞式双裂隙类岩石力学特性及裂纹扩展分析

Analysis of Mechanical Properties and Crack Propagation of Rocks with Double Holes Type Double Fissures

为了研究单轴压缩下含有双孔洞和双裂隙缺陷岩石的力学响应,通过完整类岩石室内单轴压缩试验和颗粒流程序PFC2D模拟试验试样的弹性模量和峰值强度等相关参数及破坏形态的对比分析,最终选取一组合理的细观参数,对双孔洞、双裂隙和双孔洞式双裂隙试样进行单轴压缩模拟试验。研究表明:双孔洞和双裂隙缺陷显著弱化了岩石抗压承载的力学特性,双孔洞缺陷的弱化效应大于双裂隙,随裂隙的倾角增大,双裂隙对岩石的弱化作用逐渐减小,且双孔洞和双裂隙对岩石产生的共同弱化效应小于叠加弱化效应;当裂隙的倾角较小时,试样的初始裂纹萌生于裂隙尖端和孔洞与裂隙的岩桥,孔洞与裂隙较容易贯通,随倾角增大,孔洞的上下部开始萌生初始裂纹,且当倾角为90°时,初始裂纹仅萌生于孔洞的上下部,孔洞与裂隙不贯通;双孔洞式双裂隙试样的破坏模式主要为拉伸破坏,且拉伸破坏主要发生在孔洞的上下部、外侧和裂隙的尖端,剪切破坏主要在孔洞与裂隙的岩桥产生。

In order to study the mechanical response of rocks with double cavities and double fissures under uniaxial compression,through the comparative analysis of the complete rock-like indoor uniaxial compression test and the particle flow program PFC2D simulation test sample's elastic modulus,peak strength and other related parameters and failure modes,a reasonable set of meso-parameters is selected to perform uniaxial compression simulation tests on double-holes,double-fissures,and double-holes type double-fissures specimens.Research indicates:the double-cavitys and double-fissures defects significantly weaken the mechanical properties of rock compressive bearing,the weakening effect of double holes defects is greater than double fissures.As the inclination of the fissure increases,the weakening effect of double fissures on the rock gradually weakened,and the common weakening effect of double cavities and double fissures on the rock is smaller than the superimposed weakening effect.When the inclination angle of the fissure is small,the initial cracks of the specimen sprout from the tip of the fissures and the rock bridge between the hole and the crack,holes and fissures are easier to penetrate,as the inclination angle increases,initial cracks begin to grow on the upper and lower parts of the hole,holes and fissures are not connected.The failure mode of the double-hole type double-fissures specimen is mainly tensile failure,and tensile failure mainly occurs on the upper and lower part,outside of the hole and the tip of the fissure,shear failure mainly occurs in the rock bridges of holes and fissures.