混凝土破坏特征试验与PFC仿真技术研究

Research on Concrete Failure Characteristics Test and PFC Simulation Technology

为研究PFC仿真技术在混凝土中的应用,设计了不同应变速率下混凝土的室内单轴压缩试验,对混凝土pfc模型进行了优化,分析了主要细观参数对优化模型力学特性的影响,结合室内试验验证了所用细观参数的合理性,最终分析了混凝土的破坏特征,分析发现:①混凝土模型试样的峰值应力随法向-切向刚度比增大而逐渐降低,峰值应变随法向-切向刚度比增加先增加后降低;混凝土模型试样的峰值应力、峰值应变随粘结法向强度增大而线性增加;随颗粒粘聚力增加,混凝土模型试样的峰值应力、峰值应变整体上均呈现先增大,后趋于平稳的变化趋势;②数值模型和混凝土试样单轴受压的破坏形式都为剪切破坏,骨料的分布是影响混凝土试样的破坏面形态的主要原因;③混凝土的强度主要取决于水泥砂浆的强度及其与骨料表面的黏结强度。

In order to study the application of pfc simulation technology in concrete,the designed indoor uniaxial compression tests of concrete at different strain rates,optimized the concrete pfc model,and the influence of main micro parameters on the mechanical characteristics of the optimized model was analyzed.Combined with laboratory tests,the rationality of the micro parameters used was verified.Finally,the failure characteristics of concrete were analyzed,analysis found:(1)The peak stress of the concrete model specimen gradually decreased with the increase of the normal-tangential stiffness ratio,the peak strain increased firstly and then decreased with the increase of the normal-tangential stiffness ratio;the peak stress and peak strain of the concrete model specimens increased linearly with the increase of the bond normal strength;as the particle cohesion increased,the peak stress and peak strain of the concrete model specimens increasd firstly and then tended to A steady trend of change;(2)The numerical model and the failure mode of the concrete specimen under uniaxial compression are both shear failures,and the distribution of aggregate is the main reason affecting the shape of the failure surface of the concrete specimen;(3)The strength of concrete mainly depends on the strength of cement mortar and its bonding strength with the aggregate surface.