弹性范围内加卸载时岩石波速-应力-储能对应关系研究

为了获得岩石储能的定量化表征方法,基于岩石内部储能可以通过其受载状态下岩石应力-应变关系曲线下的面积来定量化计算的原理,在实验室内测试了岩石试样在弹性范围内反复加卸载下波速-应力、应力-储能的对应关系。结果表明,对处于弹性阶段的大理岩试件进行多次反复加卸载,加载过程中波速随压应力线性增加,卸载过程中波速随压应力减少而线性下降;且同一应力下,加载对应的波速一般低于卸载时波速,但随着加卸载次数增加,这种同一应力下的加卸载波速之间的差值会越来越小,趋近于相同,此时整体的线性规律性更加明显。测试结果还显示,弹性阶段内,大理岩试样的单轴加卸载应力与能量密度较好地符合复合幂函数关系。通过应力作桥梁,构建出波速与能量之间的量化对应函数关系,从而找到了一种用波速来表征岩石储能的定量化方法。

Relationship of Wave Velocity-Stress-Energy Storage in Rocks within Elastic Range

In order to obtain a quantitative characterization for rock energy storage, the relationship among wave velocity, stress, energy storage in rock specimen under cyclic loading and unloading within the elastic range was tested based on the principle of the quantitative calculation of energy storage in the rock with the area below the stress-strain curve of rock under loading condition. It is found from tests that after several loading-unloading cycles for the marble specimen at the elastic stage, the wave velocity was linearly increased with an increase in the pressure stress during the loading process, while linearly decreased with a decrease in the pressure stress during the unloading process. Furthermore, under the same stress, the corresponding wave velocity during the loading is generally lower than that during the unloading, but such difference is tending to be less with an increase in loading-unloading cycles, showing an obvious linear relationship as a whole. Test results also showed that the uniaxial loading and unloading stress and energy density of the marble specimen were in good consistency with the complex power function at an elastic stage. Therefore, a corresponding quantitative function relationship between wave velocity and energy storage was established with the stress as a bridge, which is a quantitative method for characterization of rock energy storage with wave velocity.