微波作用对砂岩物理力学性质影响的试验

Experimental study on the effect of microwave on the physical and mechanical properties of sandstone

对微波作用后的砂岩试样开展了波速测试和单轴压缩试验,并结合差热分析和扫描电镜试验探讨了微波加热对砂岩物理力学性质的影响机制。试验表明:在微波作用下试样温度迅速升高,且功率越大,升温速率越大;微波作用后,试样纵波波速随着微波加热功率、时间的增大迅速降低;随着微波功率的增加,试样的单轴抗压强度和弹性模量先增大后减小;随着加热时间的增加,试样的单轴抗压强度先增加后减小,弹性模量则都降低。微波加热导致砂岩内部产生了不同程度的结构变化,表现为黏土矿物的失水收缩裂纹、沿颗粒边界裂纹、颗粒内部裂纹等。低功率、短时间加热时,微波加热对砂岩的强度有增强作用;高功率且长时间微波加热条件下,砂岩试样温度较高并产生明显损伤,使得强度降低。

In order to study the law of physical and mechanical properties of rock under microwave heating,the wave velocity test and uniaxial compression test were carried out on the sandstone samples heated by microwave.The influence mechanism of microwave heating on mechanical properties of rock was investigated combined with DTG and SEM.The results show that the temperature of sandstone increased rapidly under the action of microwave,and the heating rate increased with the increase of microwave power.Under the action of microwave,the wave velocity decreased rapidly with the increase of microwave power and time.With the increase of microwave power,the peak strength and elastic modulus of sandstone first increased and then decreased.With the increase of heating time,the peak strength first increased and then decreased,and the elastic modulus decreased.Microwave heating led to different degrees of structural changes in sandstone,such as water loss shrinkage crack of clay mineral,crack along particle boundary,and crack inside particle.Under low power and short time heating,microwave heating can enhance the strength of sandstone.Under the condition of high power and long-time microwave heating,the sandstone sample has high temperature and obvious damage,which reduces the strength.