田下凝灰岩应力松弛特性及数值模拟研究

岩石应力松弛特性是预测地下工程长期稳定性的重要基础。首先,对峰前、峰值和峰后区域应变水平下田下凝灰岩进行分别加载应力松弛试验,研究松弛过程中应力变化规律,并分析了应力松弛水平随应变水平的变化规律;其次;对田下凝灰岩进行分级加载应力松弛试验,研究分级加载条件下应力的变化规律,试验结果表明,分级加载和分别加载应力松弛具有相同的规律,且峰值处、峰值后的应力松弛特与峰值前的基本相似;最后,利用基于弹簧模型的可变模量本构方程对田下凝灰岩应力松弛试验进行数值模拟,试验结果与计算结果一致性很好,表明该本构方程可以较好的描述田下凝灰岩的应力松弛特性,可以预测工程流变破坏寿命。

Research on Stress Relaxation Properties and Numerical Simulation of Tage Tuff

Relaxation properties of rocks are important to forecast long-term stability of underground engineering. First, the relaxation tests of Tage Tuff were carried out under strain level in pre-failure region, peak strength and post-failure region by single-stage loading condition, and the law of relaxation was investigated from the testing results The law of stress level variety with strain level was analyzed. Second, the same relaxation of Tage Tuff was done by multi-stage loading condition. The testing results show that there are the same law of relaxation properties by the two loading condition, and relaxation properties in peak strength, post-failure region of Tage Tuff are almost similar with that in pre-failure region. Finally, the testing results are numerically simulated by the non-linear spring model, coinciding well with experimental results. It shows that the constitutive equation is suitable to describe stress relaxation properties of Tage Tuff, and rheologic failure life of practical engineering may be forecasted by it.