基于FOTP-GM(1,1)模型的聚丙烯纤维混凝土劣化过程研究

Degradation law of polypropylene fiber concrete under the freeze-thaw and dry-wet cycle coupling action

  • 摘要: 为研究西北干寒地区聚丙烯纤维混凝土建筑物受到干湿-冻融双因素耦合作用下产生的材料耐久性问题,设计室内加速试验,模拟该地区聚丙烯纤维混凝土在干湿和冻融作用下的劣化过程,并以质量损失率和抗压强度损失率为劣化指标进行研究;选用全阶时间幂灰色预测模型对抗压强度损失率变化过程进行建模,确定了对应试验工况下模型的最优结构形式。研究表明:试件的质量损失率经时变化规律为先减小、后增加、再减小直至试验结束,试件的抗压强度损失率经时变化规律为先减小、后增加直至破坏;在试验所取的纤维掺量范围内,0.9 kg/m3的纤维掺量对试件抵抗干湿-冻融破坏能力的改善效果最为明显,试验结束时该掺量下的试件还未达到破坏标准,而其他掺量下的试件均已破坏;当时间幂项阶数h=3时,全阶时间幂灰色预测模型与聚丙烯纤维混凝土劣化过程的原始数据之间的拟合度达到98%,预测值与实际值之间的相对误差低于0.15。室内加速试验和全阶时间幂灰色预测模型的结合,为混凝土结构耐久性设计及寿命预测提供了理论支持。

     

    Abstract: To study the durability of polypropylene fiber concrete (PFC) buildings in the northwest dry and cold region under the coupling effect of dry-wet and freeze-thaw cycles environment, the indoor accelerated test was designed to simulate the deterioration process of the PFC in the region under the action of dry-wet and freeze-thaw cycles environment. The mass loss rate and compressive strength loss rate were taken as the deterioration indexes. The full order time power grey prediction model was used to model the change process of the compressive strength loss rate, and the optimal structure of the model under the corresponding test conditions was determined. The results show that the mass loss rate of the specimen decreases first, then increases and then decreases until the end of the test, and the compressive strength loss rate of the specimen decreases first, then increases until the failure. In the range of fiber content taken in the test, the fiber content of 0.9 kg/m3 has the most obvious improvement effect on the resistance of the specimen under the coupling effect of dry-wet and freeze-thaw cycles. At the end of the test, the specimen with the fiber content of 0.9 kg/m3 reaches the failure standard, while the specimen under other contents is destroyed early. When the time power order h=3, the fitting degree between the full order time power grey prediction model and the original data of the deterioration process of PFC reaches 98%, and the relative error between the predicted value and the actual value is less than 0.15. The combination of indoor accelerated test and full order time power grey prediction model provides theoretical support for durability design and life prediction of concrete structures.

     

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