粗骨料嵌锁型混凝土的细观断裂机理研究

Research on Mesoscopic Fracture Mechanism of Coarse Aggregate Interlocking Concrete

摘要:

粗骨料形成的骨架对混凝土的宏观力学性能，特别是断裂性能有重要影响。基于细观力学和断裂力学，对粗骨料嵌锁型混凝土的力学性能和断裂特性进行了理论模拟和实验研究。通过理论计算，建立了粗骨料嵌锁型混凝土的断裂机理。同时，通过试验测试不同粗骨料增加率的嵌锁型混凝土的力学性能，并且结合压汞法测孔试验,分析粗骨料体积对嵌锁型混凝土力学性能和断裂特性的影响。最后，通过对比分析理论计算与实验结果之间的误差，建立了粗骨料嵌锁型混凝土的断裂机理。结果表明：混凝土的力学性能和断裂特性随着粗骨料体积的增大均呈现先增加后减小的趋势，当粗骨料体积增加一定量时，混凝土的抗压强度、抗折强度和断裂能得到显著提高。通过理论计算发现，当粗骨料增加率小于20%时，随着粗骨料体积的增大，抗压强度和弹性模量模拟结果与试验结果的计算误差逐渐趋于稳定，断裂能的模拟结果和试验结果具有相同的变化规律。故所提出的细观力学计算模型，对于预测粗骨料嵌锁型混凝土的断裂特性具有较高的精度。

Abstract:

The skeleton formed by coarse aggregate has an important influence on the macroscopic mechanical properties of concrete， especially the fracture properties . Based on meso-mechanics and fracture mechanics， this study conducted numerical simulation and experimental analysis on the mechanical and fracture characteristics of coarse aggregate interlocking concrete. Through theoretical and numerical analysis， the fracture mechanism of coarse aggregate interlocking concrete was established. Meanwhile， through testing the mechanical and fracture properties of the interlocking concretes with different increase rates of coarse aggregate， the influence of coarse aggregate volume on the mechanical and fracture properties of interlocking concrete was analyzed. Finally， the theoretical and experimental results were comprehensively discussed and analyzed. This study is beneficial for understanding the fracture mechanism of coarse aggregate interlocking concrete. The results showed that the trend of the fracture strengths of the coarse aggregate was increased and then decreased when the volume of the coarse aggregate was gradually increased. The fracture energy and ultimate strength of concrete were significantly improved by increasing the volume of the coarse aggregate. Through analyzing the simulation results of the compressive strength， elastic modulus and fracture energy， it was found that when the increase rate of coarse aggregate was less than 20%， the of compressive strength and elastic modulus between simulation and experiment were similar. The numerical and experimental results on the fracture energy were also similar . The proposed meso-mechanics calculation model has a high accuracy in predicting the fracture characteristics of coarse aggregates interlocking concrete.