The restrained ring test recommended by AASHTO and ASTM has been used for assessing the crack resistance of early-age concrete .In order to investigate the fracture mechanics of concrete in the ring test ,shrinkage was simulated through applying the fictitious temperature filed on concrete based on thermal and structural analysis module in ANSYS . Combining with the stress analysis results ,the crack location of concrete ring was determined ,combining with the ficti-tious crack model ,the crack propagation after initiation of ring specimens with circumference exposed was simulated .At the same time ,the proposed method is proved feasible because concrete cracking time from numerical results and experi -mental results agree well .It was found that concrete directly go into unstable propagation stage after crack initiation in the restrained circular ring test ,and the sudden drop of steel compressive strain represents onset of crack unstable propaga -tion .%美国国家公路与运输协会（AASHTO）及美国试验材料学会（ASTM）推荐约束圆环试验为评估早期混凝土抗裂性的标准试验方法。为了更好地研究约束圆环试验中混凝土的破坏机理，利用 ANSYS 有限元软件热学分析和结构分析模块，在混凝土上施加虚拟温度场来模拟收缩作用。结合应力分析结果确定混凝土的起裂位置，并引入虚拟裂缝模型，模拟外圆周干燥的圆环试件收缩裂缝在起裂后的扩展过程。通过对比混凝土开裂时间，预测结果和试验结果吻合良好，验证了数值模拟中提出的计算方法的可行性。结果显示，在约束圆环试验中，限制收缩裂缝形成后直接进入失稳扩展阶段，试验中钢环压应变的突然滞回反映了混凝土限制收缩条件下的失稳扩展。
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