岩石泊松比的应力依赖性

Stress Dependency of Poisson’s Ratio in Rocks

为了揭示泊松比的影响因素及现行测试方法存在的问题,阐述了岩石变形的阶段性和泊松比的主要影响因素,指出了岩石泊松比存在应力依赖性。通过单轴压缩试验、不同应力路径的加卸载试验,研究了标准岩石试样的泊松比在无侧限受压变形过程中的变化规律。试验发现,泊松比与应力水平密切相关,割线泊松比、切线泊松比和平均泊松比均随应力水平的提升而单调增大,卸载阶段的泊松比较加载阶段更为稳定,受应力水平的影响小。基于试验结果讨论了泊松比测试与取值方法,指出现行的基于单轴加载的测试方法的结果缺乏稳定性,与泊松比弹性常数的定义不符,如何获取岩石材料真实的弹性泊松效应值得进一步研究。

To reveal the influencing factors of Poisson’s ratio and the problems existing in current testing methods,this paper expounded the stages of rock deformation and the factors influencing Poisson’s ratio and pointed out that the Poisson’s ratio of rocks is stress-dependent.Uniaxial compression tests and loading and unloading tests of different stress paths were conducted to study the variation law of Poisson’s ratio of standard rock samples in the process of unconfined compressive deformation.The results show that the Poisson’s ratio is closely related to the stress level.The secant Poisson’s ratio,the tangent Poisson’s ratio and the average Poisson’s ratio all increase monotonically with the increase of the stress level,and the Poisson’s ratio in the unloading stage is more stable than that in the loading stage and is less affected by the stress level.Based on the test results,this paper discussed the method of testing and determining the value of the Poisson’s ratio and pointed out that the results of current testing methods based on uniaxial loading lack stability and are inconsistent with the definition of the elastic constant of the Poisson’s ratio.The actual elastic Poisson effect of rock materials is worthy of further study.