实时温度与循环载荷作用下花岗岩单轴力学特性实验研究

A multifunctional high-temperature triaxial rock testing machine was used to comparatively analyze the uniaxial stress - strain characteristics of granite under real-time temperature and cyclic loading through experiments, and to reveal the influence laws of temperature and cyclic loading on its mechanical properties. The research shows that: (1) Under real-time temperature, the uniaxial compressive strength and elastic modulus of granite generally show a downward trend with the increase of temperature. The variation law of the ultimate strain with temperature is in a "W" shape, that is, from 25 °C to 200 °C, the ultimate strain decreases with the increase of temperature; from 200 °C to 300 °C, it increases with the increase of temperature; from 300 °C to 500 °C, it decreases with the increase of temperature; from 500 °C to 600 °C, it increases with the increase of temperature; (2) After stress cycling, its elastic modulus generally increases, but the increase amplitude is different at different temperatures. The increase amplitude is the smallest at 100 °C and the largest at 400 °C. The increase mainly occurs in the second stress cycle, and the change of the elastic modulus in the stress cycles from the 2nd to the 50th is relatively small; (3) At 25 °C and 600 °C, the granite fails after a limited number of cycles, and the strength is lower than that before stress cycling. At other temperature points, the strength increases to different degrees after stress cycling; (4) Under the temperature conditions of 100 °C and 400 °C, the ultimate strain value of granite after 50 stress cycles is greater than that without stress cycling, and the change at other temperature points is very small. The research results have important theoretical significance and application value for the research on the stability of rock engineering under the simultaneous action of temperature and cyclic stress.

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。