黏塑性蠕变模型中屈服强度的确定方法

在岩石蠕变特性试验中,当施加的常应力达到一定程度后岩石将发生黏塑性变形,一般用屈服强度判断岩石是否发生黏塑性变形,与弹塑性理论不同,在黏塑性蠕变模型中,屈服强度并不是定值,而是随蠕变时间增长逐渐减小,确定蠕变过程中准确的屈服强度对黏塑性变形计算有重要的影响.首先,通过等时曲线法确定岩石长期强度的过程,对屈服强度随时间的...

Research on the determination method of yield strength in viscoplastic creep models

During rock creep test, when the applied stress reaches a certain degree, viscoplastic deformation will often occur. The yield strength used to determine whether viscoplastic deformation will occur or not. Different from elastoplastic theory, the yield strength is not fixed value in viscoplastic model, but decreases gradually with creep time. Therefore, it is important to determine the accurate yield strength in the creep process. In this paper, isochronous curve method is used to determine the long-term strength of rock. The variation rule of yield strength with the creep time was analyzed. The relationship between instantaneous yield strength and long-term strength was also discussed. After that, by combining the complete stress-strain curve and isochronous curve, creep deformation can be effectively judge viscoplastic deformation and what time the deformation occurs. Then the instantaneous yield strength is replaced by long-term strength in general bingham model and creep deformation is calculated and error is analyzed. The result shows the error is very small for most of the rock. However, it is also found rock types have an effect on the calculated result. The research results are helpful for the rational use of yield strength in creep model and have positive significance for creep model research.