华山花岗岩热力损伤特性及机理研究

为研究花岗岩的热力损伤特性及机理, 借助超声检测分析仪与钨灯丝扫描电镜, 分析了不同温度作用后岩石纵波波速衰减规律、损伤演化模型及细观机理。结果表明:温度低于500 ℃时, 花岗岩试样纵波波速随处理温度升高而缓慢降低, 当温度接近573 ℃, 纵波波速呈迅速下降状态, 最终渐趋于稳定; 随着加热温度的升高, 岩样的超声波波幅锐减, “拍”的长度变短; 花岗岩内部热损伤与所经历的温度之间符合logistic曲线模型; 温度在20~500 ℃范围内, 花岗岩试样中主要产生晶间裂纹, 裂纹数量随温度升高而增加; 加温至700 ℃时, 岩样中产生晶内裂纹或穿晶裂纹, 温度达到900 ℃时, 岩样出现宏观分岔裂隙。

Experimental study on thermal damage characteristics and mechanism of Huashan granite

In order to study the characteristics and mechanism of thermal damage of the granite, the analyses of attenuation law of longitudinal wave, damage evolution model and the mesoscopic mechanism of rock under different temperatures are carried out by using the ultrasonic testing analyzer and tungsten-filament scanning electron microscope (SEM). The analysis results show that when the temperature is lower than 500 ℃, the longitudinal wave velocity of the granite sample slowly decreases with the increase of treatment temperature; and when the temperature is near 573 ℃, the wave velocity drops rapidly and is gradually tends to be stable at last. With the increase in heated temperature, the amplitude of wave declines, the length of "beat" becomes shorter and the relationships between the thermal damage and the heated temperatures well follow the logistic curve model. In the range of 20 ℃ to 500 ℃, the inter-granular crack predominates; and as the temperature rises to 700 ℃, the number of microcracks increases, and the intracrystalline and transgranular crack occur. When the treatment temperature reaches up to 900 ℃, the macroscopic branching fissure appears in the sample. The research results can provide a referrence for construction of rockmass engineering after higher temperature.