高温条件下砂岩动态力学特性试验研究

为研究实时高温作用对岩石动态力学性能的影响,利用φ50 mm变截面分离式Hopkinson压杆(SHPB)试验装置及高温环境箱,对砂岩试件进行了常温(25 ℃)、100 ℃、200 ℃、400 ℃、600 ℃、800 ℃和1 000 ℃7个温度等级的冲击压缩试验,得到了不同温度砂岩试件的动态应力、应变、弹性模量和应变率等,分析了温度变化对砂岩动态力学性能和破坏形态的影响规律。试验结果表明:高温条件下砂岩试件的动态力学性能比其常温状态下发生了显著变化。随着作用温度的升高,砂岩试件的动态抗压强度表现为先增大后减小,峰值应变呈线性增加,弹性模量整体呈二次抛物线下降,平均应变率呈二次抛物线增加;试件受冲击破碎程度随作用温度的升高表现为先减少再逐渐增大的趋势,其动态破坏特征也反映了砂岩试件的强度特征。

Experimental Study on Dynamic Mechanical Characteristics of Sandstone under Actual High Temperature Conditions

To study the dynamic mechanical properties of rocks under high temperature conditions, dynamic compression tests under the same loading condition were carried out for sandstone specimens under 7 temperature levels from 25 ℃ to 1 000 ℃ by φ50 mm variable cross-section SHPB test apparatus and self-developed high temperature environmental box. Then dynamic mechanical characteristics, such as dynamic compressive strength, peak strain, dynamic elastic modulus, and average strain rate, were obtained under various actual high temperatures. And the influence of high temperature on dynamic mechanical characteristics and failure mode were analysed. Test results show that dynamic mechanical characteristics of sandstone under actual high temperature are significantly different with those at room temperature. With the increase of actual temperature, dynamic compressive strength first increases then decreases, and peak strain increases in a linear function. Dynamic elastic modulus varies in a downward quadratic parabola with actual temperature. While average strain rate varies in an upward quadratic parabola with actual temperature. Crushing degree of sandstone specimen under impact loads first decreases then increases under high temperature. Dynamic failure features of sandstone specimen under actual high temperature correspond with its strength characteristics.