The role of fractures, effective pressure and loading on the difference between the static and dynamic Poisson's ratio and Young's modulus of Westerly granite
The role of fractures, effective pressure and loading on the difference between the static and dynamic Poisson's ratio and Young's modulus of Westerly granite
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DOI：
10.1016/j.ijrmms.2019.03.001
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发表时间：
2019-04-01
影响因子：
7.2
通讯作者：
Tatham, D. J.
中科院分区：
文献类型：
--
作者：
Blake, O. O.;Faulkner, D. R.;Tatham, D. J.
岩石破裂是影响岩石弹性特性的主要因素。弹性特性可以在样本缓慢加载过程中静态测量，也可以动态测量，其中弹性可以使用弹性波速度计算。然而，静态和动态弹性特性之间存在差异。在这项研究中，对经过 250、450、650 和 850 摄氏度热处理的干燥和水饱和西风花岗岩在不同的有效压力和差动载荷下测量了动态和静态弹性特性。温度升高会导致各向同性分布的裂缝密度增加。裂缝密度的增加会导致静态和动态情况下杨氏模量的降低和泊松比的增加，这对于在 450°C 以上处理的岩石非常显着。动态杨氏模量大于静态值，并且当水饱和时它们之间的差异增大。在干燥条件下，无论裂缝密度、载荷或有效压力如何，静态杨氏模量与动态值都表现出良好的相关性。在干燥和饱和条件下，静态和动态泊松比彼此接近。然而，当裂缝密度较高、压差载荷较高、有效压力较低时，静态泊松比与动态泊松比会出现偏差。
Fracture in rock is a major factor that affects the rock's elastic properties. Elastic properties can be measured statically during slow loading of a specimen, or dynamically, where the elasticity can be calculated using elastic-wave velocity. However, differences exist between the static and dynamic elastic properties. In this study, the dynamic and static elastic properties were measured under varying effective pressures and differential loads for dry and water-saturated Westerly granite that was thermally treated to 250, 450, 650 and 850 degrees C. Increasing the temperature produces an increased fracture density that is isotropically distributed. Increased fracture density results in a reduction in the Young's modulus and an increase in the Poisson's ratio, in both the static and dynamic cases, and is very significant for rocks treated above 450 degrees C. The dynamic Young's modulus is larger than the static value and the difference between them increases when water saturated. Under dry conditions, the static Young's modulus shows good correlation with dynamic values regardless of fracture density, loading or effective pressure. The static and dynamic Poisson's ratio are close to each other under both dry and saturated conditions. However, deviation between the static and dynamic Poisson's ratio occurs when the fracture density is high, differential load is high and effective pressure is low.