围压对岩石裂纹扩展影响的颗粒流模拟研究  

Particle Flow Simulation on the Influence of Confinement on Crack Propagation in Pre-cracked Rock

作　　者：唐谦[1,2] 李云安[1] 

机构地区：[1]中国地质大学工程学院,武汉430074 [2]江汉大学文理学院,武汉430056

出　　处：《长江科学院院报》2015年第4期81-85,共5页Journal of Changjiang River Scientific Research Institute

基　　金：湖北省自然科学基金重点项目(2012FFA047)

摘　　要：采用颗粒流数值软件PFC模拟预设单裂隙岩石在双向压缩状态下裂纹的扩展过程和特征。首先利用黏聚颗粒模型建立岩石试样,并在岩石试样中预置非贯通单裂隙;为研究围压对岩石裂纹扩展的影响,分别在5种围压作用下对预设裂隙岩石进行双轴压缩试验。结果表明:在围压为0(单轴压缩)时,翼裂纹扩展方向与预设裂隙基本垂直,随着加载进行沿着主压力方向扩展,而当围压增加时,翼裂纹扩展方向与预设裂隙的交角增大,且长度变短直至围压到达一定值后不再发育;次生裂纹的扩展方向不仅与材料的性质有关,同时受到围压值的影响;围压增大对张性裂纹扩展产生限制,并促进剪性裂纹的扩展和合并,且最终剪切破坏面的宽度随着围压的增大而增大;次生裂纹可以由拉应力产生,但其进一步发育和扩展受到剪应力的控制。Confining pressure significantly affects the crack propagation in pre-cracked rock.Particle flow simulation is a frontier approach of researching the features and mechanism of crack propagation.In this paper we present a numerical procedure for the analysis of crack propagation in rock-like materials under compressive biaxial loads. Rock specimens with intermittent single cracks were built by a bonded particle model （BPM）and biaxial compres-sion tests under five different confinements were modeled in PFC2D （2 dimensional particle flow code）.Results re-veal that when the confining pressure is 0 （which means uniaxial compression）,wing cracks initiate perpendicular to the pre-existing cracks and propagate towards the direction of principal stress;however,when confining pressure increases,the angle between wing cracks and pre-existing cracks gets larger,and the wing cracks get shorter and stop developing until confining pressure reaches a certain value.Also we conclude that in addition to material type, the direction of secondary crack propagation depends on the confining pressure,too.Besides,secondary cracks can be triggered by tensile stress but the further development is affected by shear stress.The increase of confining pres-sure poses constraints to the development of tensile cracks,but promotes shear cracks,and the width of shear plane gets larger with confinement increasing.

关 键 词：裂隙岩石 裂纹扩展 双轴数值压缩试验 PFC 黏聚颗粒模型 

分 类 号：TU45[建筑科学—岩土工程]