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为研究混凝土动态力学性能、解释混凝土材料动力破坏机理,该文基于颗粒元(PEM)建立细观模型,模拟混凝土动力弯曲试验,并进行率效应研究。数值仿真中以不同加载速率进行弯曲试验,得到混凝土抗弯强度的率相关强度增长系数(DIF),再现了不同应变率下弯曲破坏模式。数值仿真模拟得到的弯曲应力-应变结果和破坏现象与试验吻合良好,证明了数值模型的有效性。通过对破坏过程进行分析,高应变率条件下混凝土梁产生多条裂纹,表现出与低应变率条件完全不同的破坏形式,这是混凝土动强度提高的主要机理。
In order to study the dynamic mechanical properties of concrete and explain the dynamic failure mechanism of concrete materials, this paper establishes a mesoscopic model based on Particle Element (PEM), simulates the dynamic bending test of concrete, and studies the rate effect. In the numerical simulation, the bending test was carried out at different loading rates to get the rate-dependent strength growth coefficient (DIF) of flexural strength of concrete, and the bending failure modes under different strain rates were reproduced. Numerical simulation results show that the bending stress-strain and failure phenomena agree well with the experimental results, which proves the validity of the numerical model. Based on the analysis of the failure process, the concrete beams with a high strain rate produce a series of cracks, which show completely different forms of failure with the low strain rate conditions, which is the main mechanism for the increase of the dynamic strength of the concrete.