泥质白云岩干湿循环力学特性试验研究及其本构模型

水岩相互作用一直是研究的热点课题,水岩相互作用使岩石性质劣化,影响岩石的强度。以泥质白云岩为研究对象,进行了干湿循环作用后的单轴和三轴压缩试验,研究了不同循环作用下岩石的强度、变形等力学特性,并运用连续损伤力学和统计理论,推导出干湿循环作用下岩石的损伤统计本构模型。试验结果表明:泥质白云岩峰值强度随干湿循环次数增加而减小;泥质白云岩在单轴压缩试验中,岩石的总劣化度随干湿循环次数增大呈增大的趋势,而各阶段的劣化度和平均劣化度逐渐降低并趋于稳定;三轴压缩试验中,岩石的总劣化度随围压增加而总体呈现先减小再增加的趋势,较高次的循环对岩石的强度影响大于较高的围压作用对其影响;岩石的弹性模量随干湿循环次数的增大呈总体减小的趋势。通过对比理论曲线与试验曲线可知,本构模型能够较好地反映岩石三轴应力-应变关系,验证了该模型的合理性。

Experimental Study on Mechanical Properties of Argillaceous Dolomiteunder Dry-Wet Cycles and Its Constitutive Model

Water-rock interaction has always been a hot topic of research. Water-rock interaction deteriorates rock properties and affects the strength of rock. In this paper, the strength and deformation of argillaceous dolomite undergone different dry-wet cycles are investigated through uniaxial and triaxial compression tests. Moreover, the damage statistic constitutive model of rock under dry-wet cycles is derived based on the continuous damage mechanics and statistical theory. Results reveal that: the peak strength of argillaceous dolomite declines with the proceeding of cyclic drying and wetting. In uniaxial compressive test, the total deterioration degree of argillaceous dolomite increases in general with the increase of dry-wet cycles, while the staged deterioration degree and average deterioration degree gradually reduces and tends to be stable. In triaxial compressive test, the total deterioration degree of argillaceous dolomite decreases before increasing with the climbing of confining pressure. Larger number of cycle has a greater effect on the deformation of rock than higher confining pressure does. The elastic modulus of argillaceous dolomite also declines basically with the proceeding of cyclic drying and wetting. Comparison between theoretical curves and experimental curves demonstrates that the constitutive model well reflects the triaxial stress-strain relationship of rock, hence is rational.