多裂纹相互作用下混凝土断裂参量的有限元数值分析

基于虚拟裂纹闭合技术（VCCT），采用有限元分析方法对具有预制中心裂纹的三点弯曲混凝土梁的能量释放率G和应力强度因子K进行了分析计算，应力强度因子的计算结果和相关的理论结果具有较好的一致性，验证了该方法的有效性。然后，考虑2条对称的副裂纹，分析计算了混凝土梁的副裂纹长度对主裂纹应力强度因子的作用效果，获得了副裂纹长度对主裂纹应力强度因子的影响规律。最后，固定主裂纹和副裂纹的长度，改变副裂纹的位置，在多裂纹相互作用下，对混凝土梁副裂纹与主裂纹之间的相对位置对主裂纹应力强度因子的影响进行了计算，得出了副裂纹位置变化对主裂纹应力强度因子的影响规律。该数值方法的建立，对处理和计算混凝土的多裂纹断裂问题具有较好的工程应用前景。

Finite element numerical analysis of fracture parameters of multiple interacting cracks in concrete

The energy release rate and the stress intensity factor for a 3-point bending concrete beam with multiple cracks were(evaluated) using the virtual (crack) closure technology(VCCT)and the finite element method(FEM).Quantitative comparisons between the numerical and theoretical values were made,and the results showed that they were in good agreement.Then,two symmetrical minor cracks were placed in the structure,and the effects of variation in the lengths of the minor cracks on the stress intensity factors of the main crack were analyzed.Finally,if lengths of the main crack and the minor cracks were given,the rule of the stress intensity factors of the main crack with the variation in locations of the minor cracks was obtained.The developed numerical method for fracture(problems) of concrete with multiple cracks was(presented) for engineering application.