【摘要】 采用多功能岩石高温三轴实验机,通过实验对比分析花岗岩在实时温度和循环载荷作用下的单轴应力–应变特性,揭示温度与循环载荷对其力学特性的影响规律,研究表明:(1)实时温度下花岗岩的单轴抗压强度和弹性模量随温度升高总体呈下降趋势。极限应变随温度的变化规律呈"W"型,即25℃～200℃,极限应变随温度升高而降低;200℃～300℃,随温度升高而增大;300℃～500℃,随温度升高而降低;500℃～600℃,随温度升高而升高;(2)经应力循环后其弹性模量普遍提高,但温度不同提高的幅度不同,100℃时提高的幅度最小,400℃时提高的幅度最大,提高值主要发生在第2次应力循环,从第2～50次的应力循环中弹性模量的变化较小;(3)在25℃和600℃,花岗岩经有限的几次循环后便发生破坏,强度较应力循环前有所降低,而在其他温度点,经应力循环后其强度有不同程度的提高;(4)花岗岩在100℃和400℃温度条件下,经过50次应力循环后的极限应变值大于无应力循环的极限应变,其他温度点的变化非常微小。研究结果对涉及温度和循环应力同时作用下岩石类工程稳定性研究具有重要的理论意义和应用价值。更多还原

【Abstract】 The uniaxial stress-strain tests of granite under different temperatures and cyclic loads were performed utilizing the multi-functional rock high temperature triaxial testing machine,and the effect of the temperature and the cyclic load on the mechanical properties of granite was revealed. The results show that the uniaxial compressive strength and elastic modulus of granite decrease generally with increasing the temperature. The ultimate strain changes with the temperature in W shape. Specifically,the ultimate strain of granite firstly decreases with rising the temperature from 25 ℃ to 200 ℃,secondly increases from 200 ℃ to 300 ℃,thirdly decreases from 300 ℃ to 500 ℃ and then increases from 500 ℃ to 600 ℃. The elastic modulus of granite increases generally due to cyclic loads,and the increase amplitude is different with different temperatures with the minimum and maximum values at 100 ℃ and 400 ℃ respectively. The increase of the elastic modulus mainly occurs in the second stress cycle but is not obvious from the second to the 50 th stress cycle. At 25 ℃ and 600 ℃,granite samples fail after a limited number of stress cycles,and the strength is lower than that without stress cycle.However,the strength of the samples after stress cycle shows different degrees of increase at other temperatures.The ultimate strain of granite subjected to 50 stress cycles is greater than that without stress cycle at 100 ℃ and400 ℃ but changes slightly at other temperatures. The research results have important theoretical significance and application value for the study of engineering stability under the simultaneous action of temperature and cyclic stress.更多还原