【摘要】 动弯拉强度是高拱坝抗震设计中的控制性指标之一。有关试验发现一定预静载水平对混凝土动弯拉强度有强化作用,因此,对这一试验现象的探究具有工程应用价值。本文基于混凝土细观力学方法,对湿筛和全级配混凝土梁进行三分点冲击弯拉数值模拟,试图在不同随机骨料模型和不同静预载作用下寻求混凝土梁动弯拉强度的变化规律。计算结果显示,不同细观骨料模型具有相似的规律,即随预静载增大,混凝土动弯拉强度上升,至一定峰值后回归到静载强度。取跨中不同细观区域宽度和具有不同变异性的细观界面单元材料参数,对梁进行三分点弯拉数值模拟发现,动弯拉强度受混凝土细观结构不均匀性的影响,不均匀性越强动载增强系数越大。更多还原

【Abstract】 The concrete dynamical bending strength is one of the control parameters in high arch dam design. So, an investigation on the dynamical bending strength enhancement under static pre-loading would be of great potential engineering value. The different aggregate distributions are used to a numerical simulation of the dynamical bending strengths of concrete tri-section beams subject to impact load, which results in an almost similar law. The law shows that, along with the static pre-load increasing, the dynamical bending strength of concrete would go up to a peak value and then move downward to the static strength. The simulation executed for different meso-structure areas of the mid-beam and different variances of elemental mechanical parameters reveal that the more heterogeneous of the concrete meso-structure, the higher enhancing factors of the dynamic bending strength of concrete.更多还原