高寒地区后张PC梁孔道冻胀损伤研究

预应力孔道内压浆料浆液及自由水冻胀致使混凝土沿纵向开裂，是高寒地区后张预应力混凝土（PC）梁特有的病害，严重影响结构的安全性、适用性、耐久性.为了明确病害特征，对冻胀受损梁体进行钻孔和解剖检测，进一步精细定量地研究冻胀效应，采用有限元软件ABAQUS建立孔道冻胀非线性模型，开展压浆料浆液冻胀行为分析和自由水冻胀参数分析，研究孔道内压浆液冻胀率和自由水体积的控制指标.研究结果表明：高寒地区后张PC结构孔道压浆后，受冻并先后发生压浆料浆液冻胀和自由水冻胀，致使孔道周围混凝土反复受拉而沿纵向开裂；压浆料浆液的体积膨胀率宜控制在0.80%以内，最高不得超过1.73%；泌水体积比宜控制在0.04%以内，最高不得超过0.52%，由此可有效降低孔道内压浆液及自由水冻胀的风险.

Damage of Post-Tensioned PC Girders in Alpine Regions Due to Frost Heaving in Ducts

Longitudinal cracks of concrete caused by frost heaving of grouting slurry and free water in ducts is a special damage of post-tensioned PC girders in alpine regions, which affects the safety, serviceability, and durability of the structures significantly. In order to study damage characteristics, borehole and anatomical detections were conducted on damaged girders. The finite element software ABAQUS was used to establish the nonlinear models of frost heaving. Frost heave analysis of grouting slurry and parametric analysis of free water were carried out to study frost heave effects quantitatively. Control indexes of the frost heave ratio of grouting slurry and the volume of free water were obtained. The results show that the frost heaving of grouting slurry and free water occurs successively after grouting the ducts of the post-tensioned PC structures in alpine region, causing concrete to be tensioned repeatedly and cracked along the longitudinal direction. The volume expansion ratio of grouting slurry needs to be controlled within 0.80%, and the maximum should not exceed 1.73%. The volume ratio of bleeding water should be controlled within 0.04%, and the maximum should not exceed 0.52%. Thus, the frost heaving risk of grouting slurry and free water in ducts can be reduced effectively.