分数阶黏弹塑性蠕变模型试验研究

EXPERIMENTAL STUDY OF FRACTIONAL VISCOELASTIC-PLASTIC CREEP MODEL

现行利用等时曲线求长期强度的方法往往有以下两点不足:一是曲线上拐点不明显,确定长期强度带有一定的随意性;二是试验时间偏短、加载级数偏少,结果不够准确。针对湖北江汉盐岩进行为期约5个月的蠕变试验研究,获得较好的试验结果。试验得出的等时曲线上出现明显拐点,由此确定其长期强度。试验时间长和加载级数多有力地保障了试验结果的精度,可为实际工程提供参考。在前人研究成果基础上,通过两点改进建立新的分数阶黏弹塑性蠕变模型。并从推导过程、拟合结果和理论分析3个方面证实了改进后的模型更加简单、合理。

There were usually two drawbacks in calculating the long-term strength through isochronal curves. One was that the inflection point of the isochronal curve was generally not so apparent leading to the determination of the long-term strength with uncertainties. The other was that the testing time was usually short with only few loading steps,so the test results were not accurate enough. Therefore, the creep test to the salt rock from Jianghan in Hubei province in this study was carried out for about five months long. There was an obvious inflection point on the isochronal curve plotted according the test data and the long-term strength was thus determined without uncertainty. The longer testing time and the more loading steps were proved to be the vital measure to guarantee the credibility of the test results. A new fractional viscoelastic-plastic creep model was established according to the experimental results together with the improvements in two aspects. The proposed model was proved to be simpler and more reasonable in terms of the process of derivation,the outcome of test data fitting and the results of theoretical analysis.