摘要:
为研究加载速率对试件强度、变形以及破坏形式的影响,利用刚性试验机对类煤岩试件进行了不同加载速率的单轴压缩试验。借助于颗粒离散元程序PFC建立了煤岩平行黏结颗粒模型,并对不同加载速率下试件内部损伤破裂的声发射信息进行了实时记录;基于数值模型的声发射信息建立了煤岩损伤演化方程。结果表明:随着加载速率的增大,试件单轴抗压强度增大,并且试件破坏形态从多宏观断裂面的Ⅹ形、V形、Y形向单一宏观断裂面转变,整体破碎程度降低;随着加载速率的增大,试件变形破裂过程中,应力峰值附近的声发射率明显升高,表现出声发射活动更为剧烈;试件损伤演化过程基本上分为初始损伤阶段、损伤稳定发展阶段和损伤迅速发展阶段,加载速率对损伤演化的影响主要集中于损伤稳定发展阶段,即加载速率越大,试件越早进入损伤稳定发展阶段。
Abstract:
In order to study the influence of loading rate on the strength, deformation and failure modes of specimens, the uniaxial compression tests of coal-rock-li ke specimens at different loading rates are carried out by stiff testing machine. A parallel bonding particle model of coal and rock is established by means of the particle discrete element program ( PFC) and acoustic emission information of specimens damage under different loading rates is recorded in real time. Based on the acoustic e mission information of numerical model, the evolution equation of coal and rock damage is established. The results showed that uniaxial compressive strength continual ly increases with the increase of loading rate; with the increase of loading rate, specimen failure mode transforms from X、V、Y types to a single macro fracture; with th e increase of loading rate, the acoustic emission rate is obviously higher near the peak stress; damage evolution process is basically divided into the initial damage pha se, damage stable development phase and damage rapid development phase; the influence of loading rate on the damage evolution is mainly focused on the stable dev elopment phase.
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