端部摩擦约束对混凝土单轴动态压缩强度影响分析

Effect of end friction confinement on uniaxial dynamic compressive strength of concrete

混凝土宏观力学行为与其微/细观结构密切关联,考虑内部结构非均质性的影响,假定混凝土是由骨料、砂浆基质及界面过渡区组成的复合材料,建立了考虑端部摩擦约束的混凝土细观力学模型。以单轴压缩情况为例,针对不同的端部约束条件,模拟了中低应变率水平下混凝土的动态压缩行为,分析了端部摩擦约束对混凝土动态压缩力学特性尤其是动态强度的影响机理。数值结果表明:1相同加载速率下,混凝土动态压缩强度随端部摩擦因数的增大先增大,后逐渐趋于平稳;2端部摩擦约束效应改变了混凝土的单轴受力状态及损伤分布,对混凝土单轴压缩强度的提高有明显的贡献;3端部摩擦约束条件相同时,摩擦贡献因子随应变率的增大呈减小趋势,且端部摩擦因数越大,减小的趋势越明显。

Macro mechanical behavior of concrete is closely related to its micro-/meso-scale structure. Consideringthe influence of heterogeneity of interior structure , a meso-scale mechanical model was established end friction confinement , concrete was composed of aggregate particles , mortar matrix and the interfacial transition zonesbetweenthe two phases. Aiming at different end friction confinements , the uniaxial dynamic compressive mechanicalbehaviors of concrete subjected to different medium and low strain rates were simulated. Furthermore , the influencemechanism of end friction confinement on the uniaxial dynamic compressive mechanical properties , especially , thecompressive strength of concrete was analyzed. The simulation results indicated that ① with increase in end frictioncoefficient , the uniaxial compressive strength of concrete increases firstly and then becomes flat under the same loadingrate; ② the end friction confinement changes the local stress state and damage distribution of concrete , and it contributesto the increase in compressive strength of concrete obviously; ③ the friction contribution factor with increase in the strain rate , and it decreases obviously when the end friction friction confinemeer.