含弧形裂隙花岗岩裂纹扩展特征PFC模拟  

PFC simulation on crack coalescence behavior of granite specimens containing an arc fissure

作　　者：武世岩 黄彦华 WU Shiyan;HUANG Yanhua(School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China;State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]中国矿业大学力学与土木工程学院,江苏徐州221116 [2]中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州221116

出　　处：《中南大学学报（自然科学版）》2023年第1期169-182,共14页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51909260);江苏省自然科学基金资助项目(BK20221547);中国博士后科学基金资助项目(2021M693424)。

摘　　要：为了研究非直裂隙对岩石强度及破裂特征的影响,对含弧形裂隙岩样进行单轴压缩模拟,探讨弧形裂隙几何参数对试样宏细观力学行为的影响规律。首先,利用颗粒流程序(PFC)构建花岗岩试样数值模型,通过与完整和含单直裂隙试样室内试验结果进行比较,标定1组能够反映花岗岩力学特性的细观参数。在此基础上,对含不同裂隙倾角α和裂隙长短轴比γ的弧形裂隙试样进行单轴压缩模拟。研究结果表明:1)含弧形裂隙试样的峰值强度和弹性模量随着α增大而增大。当α=0°和45°时,试样的峰值强度和弹性模量随着γ的增大而增大;当α=90°时,试样的峰值强度和弹性模量随着γ的增大而减小。2)含弧形裂隙试样主要发生拉伸破坏,初始裂纹在裂隙尖端萌生,随着α增加,试样的破坏程度逐渐增大;γ主要影响裂纹类型、数量和萌生位置。3)首先在弧形裂隙尖端出现应力集中,初始裂纹产生后在裂纹尖端附近出现应力集中,微裂纹逐渐聚集、连通形成宏观裂纹,宏观裂纹的不断扩展导致试样破坏。In order to study the influence of non-straight fissures on rock strength and fracture characteristics, the simulation of specimens containing an arc crack under uniaxial compression was carried out to explore the influence of geometric parameters of arc fissure on the macro-and micro-mechanical behavior. Firstly, a simulation model of granite sample was established in particle flow code(PFC). Based on the experimental results of intact and single-straight-fissured granite specimens, a set of microscopic parameters that can reflect the mechanical properties of granite were obtained. Then, the uniaxial compression tests of the specimens containing an arc fissure which has different fissure angle α and the ratio γ(γ represents the ratio of semi-minor axis of ellipse to semi-major axis of ellipse). The results are as follows. 1) The peak strength and elastic modulus of granite specimens containing an arc fissure increase with the increase of α. When α is 0° or 45°, with the increase of the γ,the peak strength and elastic modulus of the specimens increase. And the peak strength and elastic modulus decrease with the increase of γ when α is 90°. 2) Tensile failure occurs in most specimens and the initial crack initiates at the fissure tip. With the increase of α, the damage extent of the specimen increases gradually, and the change of the γ mainly affects the type, number and initiation positions of cracks. 3) The stress concentration areas mainly appear at the prefabricated fissure tips before cracks initiation. After the initial cracks are generated, the stress is concentrated at the cracks tip. The coalescence of micro-cracks results in the formation of macro-cracks,and the continuous expansion of macro-cracks leads to the failure of the specimens.

关 键 词：岩石力学 花岗岩 弧形裂隙 裂纹演化 颗粒流程序 

分 类 号：TU45[建筑科学—岩土工程]