高温状态下加载速率对石灰岩力学效应研究

采用美国MTS810电液伺服材料试验机，对200 ℃高温状态下的石灰岩试件进行了5级不同加载速率下的单轴压缩试验，考察了石灰岩的全应力-应变曲线，给出了其峰值强度、峰值应变、弹性模量E随加载速率的变化特征。研究结果表明，(1) 石灰岩的峰值强度、弹性模量在加载速率v = 0.000 5～0.005 mm/s内，随加载速率增大呈急剧上升现象；当v = 0.005 0～0.5 mm/s内，随加载速率增大呈下降趋势；当v >0.5 mm/s后，呈现上升趋势。(2) 石灰岩的峰值应变在v = 0.000 5～0.005 mm/s内，随加载速率增大呈下降趋势；在v = 0.005～5.0 mm/s加载速率区段，峰值应变呈现缓慢上升现象。研究结果可为相关岩体的爆破效应及评价岩石工程的稳定性提供参考。

Experimental study of the mechanical effects of loading rates on limestone at high temperature

The experimental tests for limestone specimens at 200 ℃ in uniaxial compression were carried out to study the mechanical effects of loading rates on limestone using the Rock Mechanics Servo-controlled Testing System MTS810, in which loading rate was treated as a variable. The mechanical properties of limestone such as the stress-strain curve, the variable characteristics of peak strength and the modulus of elasticity of limestone were studied under the loading rates ranging from 0.000 5 mm/s to 5.0 mm/s. The results show that (1) With the rise of the loading rates, the peak strength and elastic modulus of limestone increase sharply from 0.000 5 mm/s to 0. 005 mm/s at 200 ℃; bat show downward trend when the loading rates from 0.005 mm/s to 0. 5 mm/s; and show increase trend when loading rates over 0.5 mm/s. (2) The peak strain of limestone shows downward trend when the loading rates from 0.000 5 mm/s to 0.005 0mm/s; however, the peak strain increases slowly when the loading rates over 0.005 mm/s. The result can provide valuable references for the rock blasting effect and the rock engineering stability.