Abstract To study the influence of gradient stress on the evolution characteristics of the temperature field during rockburst, the gradient and hydraulic-pneumatic composite loading true-triaxial apparatus was used to perform the rockburst tests under true-triaxial gradient loading. The temperature data of the unloading face of each sample under gradient loading were continuously recorded using the infrared thermal imager until the rockburst occurred. For the high-temperature points in temperature field, the variance-mean ratio (VMR) was introduced and the relative average temperature of high-temperature points (RAHPT) was proposed for joint analysis to quantify the evolution characteristics of temperature field. It was found that: (1) the VMR and RAHPT adopted in this paper successfully reflect the evolution characteristics of the temperature fields of all the samples under different stress gradients. The VMR and RAHPT increase initially with the increasing loads but subsequently show upward or downward trends in the late stage of loading under different stress gradients; (2) the VMR and RAHPT curves of each sample exhibit similar trends and obvious changes in phase with the increasing load; (3) the samples show obvious differences in rockburst precursors under different stress gradients, and the temperature differentiation of unloading faces appears shortly before the rockbursts, accompanied by the sudden increases in the VMR and RAHPT curves under high stress gradients; (4) the temperature anomalies that occurred on the samples under loading indicate the damage zones of the impending rockbursts. The research results provide a theoretical basis for infrared early-warning technology of rockbursts in underground openings.

中文翻译：

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不同应力梯度下岩爆样品温度场演化特征

摘要 为研究梯度应力对岩爆过程中温度场演化特征的影响，采用梯度-水气复合加载真三轴仪进行真三轴梯度加载下的岩爆试验。使用红外热像仪连续记录梯度加载下每个样品卸载面的温度数据，直到发生岩爆。针对温度场中的高温点，引入方差均值比(VMR)，提出高温点相对平均温度(RAHPT)进行联合分析，量化温度场的演化特征。结果发现：(1) 本文采用的VMR和RAHPT成功地反映了所有样品在不同应力梯度下的温度场演化特征。VMR 和 RAHPT 最初随着载荷的增加而增加，但随后在不同应力梯度下的加载后期呈现上升或下降趋势；(2)各样品的VMR和RAHPT曲线随着负载的增加呈现出相似的趋势和明显的相位变化；(3) 样品在不同应力梯度下岩爆前兆差异明显，卸荷面温度分异出现在岩爆前不久，伴随着高应力梯度下VMR和RAHPT曲线的突然增大；(4) 载荷作用下样品出现的温度异常表明即将发生的岩爆破坏区。研究成果为地下洞口岩爆红外预警技术提供了理论依据。