基于等幅周期荷载下软岩Bingham本构模型的研究

发布时间：2018-05-04 11:45

本文选题：岩石力学 + 软岩　；参考：《水利水电技术》2017年11期

【摘要】：为建立一种描述等幅周期荷载下软岩应变特性的本构模型,将Bingham模型中的常值黏壶元件替换成与循环次数相关的变系数黏壶元件,常值弹性元件替换为随周期荷载循环次数的增大而衰减的非定值弹性元件,即可得到反映周期荷载下软岩各种应变规律的Bingham本构模型。当循环荷载应力上限值σmax大于岩石的临界强度σs时,模型为可反映软岩3个应变阶段的改进4参数Bingam模型;反之则为反映软岩前两个应变阶段的非常值2参数Hook模型。将周期荷载分解为一个定值荷载和一个平均应力值为零的周期荷载,基于流变力学理论给出了定值荷载作用下基于该模型的本构方程式,再根据黏弹性力学理论,给出了平均应力值为零的周期荷载下基于该模型的本构方程式,最后将已获得的本构方程式叠加即得到周期荷载下软岩本构方程式。结果表明:所建立的本构方程式可较好描述周期荷载下不同软岩各类应变特征,对各类软岩的应变曲线拟合的相关系数均在0.868以上,且同一种岩石模型中弹性元件系数初始值随周期荷载的动应力幅值的增大而减小,岩石加速应变速率参数随动应力幅值的增大而增大。
[Abstract]:In order to establish a constitutive model to describe the strain characteristics of soft rock under constant amplitude cyclic loading, the constant viscosity pot element in the Bingham model is replaced by a variable coefficient viscosity pot element related to the number of cycles. The constant elastic element is replaced by the non-constant value elastic element which attenuates with the increase of the cyclic number of cyclic loads, and the Bingham constitutive model reflecting the various strain laws of soft rock under periodic load can be obtained. When the upper limit value of cyclic load stress 蟽 max is greater than the critical strength 蟽 s of rock, the model is an improved four-parameter Bingam model which can reflect the three strain stages of soft rock, and the non-constant value 2-parameter Hook model which reflects the first two strain stages of soft rock. The periodic load is decomposed into a constant load and a periodic load with zero mean stress. Based on the rheological theory, the constitutive equation based on the model is given, and then the viscoelastic mechanics theory is used. The constitutive equation based on this model is given under the periodic load with zero mean stress. Finally, the constitutive equation of soft rock under periodic load is obtained by superposing the obtained constitutive equation. The results show that the constitutive equations can well describe the strain characteristics of different soft rocks under cyclic loading, and the correlation coefficients of the fitting of strain curves for each kind of soft rock are above 0.868. In the same rock model, the initial value of elastic element coefficient decreases with the increase of dynamic stress amplitude of periodic load, and the acceleration strain rate parameter of rock increases with the increase of dynamic stress amplitude.
【作者单位】：贵州大学国土资源部喀斯特环境与地质灾害重点实验室;贵州大学土木工程学院;中国水利水电科学研究院;
【基金】：国家自然科学基金项目(51168009)
【分类号】：TU45

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