冻融循环作用下泥岩的力学特性及损伤机理研究

Study on Mechanical Properties and Damage Mechanism of Mudstone Under Freezing-thawing Cycle

为研究冻融循环作用下岩石的损伤特性及发展规律,以泥岩为例,对泥岩在不同次数冻融循环条件下进行了单轴压缩和超声波检测试验,并分析在不同冻融循环条件下泥岩的力学特性。结果表明:随着冻融循环次数的增加,试样的原生裂隙受到反复冻胀荷载的作用引起损伤,试样脆性减小、延性增大,单轴抗压强度、弹性模量以及纵波波速均减小;对各力学参数的劣化规律及损伤机理进行了研究,建立了呈指数型衰减的模型,结果表明单轴抗压强度、弹性模量和纵波波速的劣化随冻融循环次数的增加而增大,但增大速率却逐渐减小,趋于稳定;最后,基于波阻抗为损伤变量,建立泥岩的冻融损伤方程,结果表明泥岩的损伤随着冻融循环次数的增加而增大,但增大速率逐渐降低。

In order to study the damage characteristics and development law of mudstone under freezing-thawing cycle,uniaxial compression and ultrasonic testing of mudstone under different freezing-thawing cycles were carried out,and the mechanical properties of mudstone under different freezing-thawing cycles were analyzed.The results show that with the increase of freezing-thawing cycles,the original crack of the sample was damaged by repeated frost heave load,and the ductility of the sample increases,brittleness,uniaxial compressive strength,elastic modulus and compressional wave velocity all decrease.The degradation law and damage mechanism of mechanical parameters were studied,and an exponential decay model was obtained,the model shows that the degradation of uniaxial compressive strength,elastic modulus and compressional wave velocity increases with the increase of freeze-thaw cycles,but the increasing rate decreases gradually and tends to be stable.At last,a freeze-thaw damage equation of mudstone was established based on the wave impedance as the damage variable.The results showed that the damage of mudstone increased with the increase of freeze-thaw cycles,but the increase rate gradually decreased.