循环荷载作用下软岩力学性能试验研究

通过泥岩和页岩的单轴动循环荷载试验,对泥岩和页岩在动荷载作用下的动应力-应变发展特征进行了研究,重点分析了滞回环面积、动弹性模量及阻尼特性变化特征。结果表明:1页岩在循环荷载作用下的动应力-应变曲线为稳定型,泥岩表现为破坏型;2在相同的循环应力下,页岩的滞回环面积经历初始快速增加后变得平缓,泥岩的滞回环面积在初始时快速增加,经历短暂的缓慢递增后快速降低;3页岩动弹性模量随循环次数增加基本不受影响,泥岩动弹性模量在循环初期有所降低,当循环次数达到30次时,动弹性模量迅速降低;4页岩阻尼比和阻尼系数在循环荷载作用下基本保持不变,泥岩阻尼比和阻尼系数在循环初期基本保持不变,但当循环次数达到30次时,就会突然降低。5在相同的循环荷载作用下,页岩力学性能基本上保持不变,泥岩力学性能随着循环次数增加而快速衰减。

Experimental study on the mechanical behavior of soft rock under cyclic loading

The study aims at understanding the dynamic characteristics of the strain-stress relation of shale and mudstone through dynamic uniaxial test under cyclic loading. The dynamic analysis focuses on the area of the hysteresis loop, dynamic modulus of elasticity, and the damping characteristics. The experimental results are summarized as follow: (1) The dynamic stress-strain curve is stable for shale under cyclic loading, whereas the stress-strain curve is classified as destructive type for mudstone. (2) The hysteresis loop for shale is flattened after rapid increase in the initial phase, while the area of the hysteresis loop for mudstone experiences rapid increase in the initial phase, followed by a gradual increase and subsequently a rapid decline under identical loading condition. (3) No significant influence is observed on the dynamic elastic modulus of shale under cyclic loading. The modulus for mudstone decreases initially and then drops substantially after 30 loading cycles. (4) The damping ratio and damping coefficients remain unchanged for shale, yet these parameters for mudstone remained constant at the beginning of the loading cycles and suddenly decrease after 30 cycles. (5) In contrast to the consistencies in the mechanical properties of shale, the mechanical properties for mudstone attenuate with the increase of loading cycles.