结合内时理论研究岩石衰减与应变振幅的关系  

A Study on the Relationship Between Attenuation and Strain Amplitude in Rock Using Endochronic Theory

作　　者：温丹[1] 施行觉[1] 

机构地区：[1]中国科学技术大学地球和空间科学院,安徽合肥230026

出　　处：《实验力学》2004年第1期19-23,共5页Journal of Experimental Mechanics

基　　金：国家自然科学基金项目(40274057);地震科学联合基金项目(102099)

摘　　要：本文将解决复杂弹塑性问题的有效工具内时理论,引入到岩石衰减的研究中来。根据内时理论,简要推导了在中等应变条件下,岩石衰减与应变振幅的用非弹性参数α表示的具体关系式。在MTS压机上,对砂岩、花岗岩等多种岩石样品进行了一系列的循环加卸载实验。利用应力应变滞回曲线的面积,根据衰减的能量损耗的定义,计算了各种实验条件下的岩石样品的衰减值。实验数据表明,在各次循环平均应力相等的条件下,岩石样品的衰减随应变振幅的增加而增加,与内时理论的推导结果相一致。最后,对表示岩石非弹性的参数α进行了简要的讨论。砂岩的α值较为稳定,在0.5左右;而花岗岩的α值变化较大,但二者都随着应力的增加而增加。该实验结果对地震波在地球介质中的衰减研究有一定的参考意义。Endochronic theory is employed herein to study the attenuation of rock, under cyclic loading. According to endochronic theory, the relationship between attenuation and strain amplitude of rock samples can be briefly at intermediate strain levels by introducing an inelastic parameter α. A derived series of uniaxial stress cycling tests were conducted on sandstone and granite sample′s using MTS testing machine, and a set of hysteresis graphs of stress-strain were obtained. The attenuation values of rock samples were calculate based upon the area under those stress-strain curves. It is found that the theoretical predictions by e.t. agree well with the experimental findings which show that attenuation increases with strain amplitude when the average stress of each loop is fixed. Finally, the inelastic parameter α was briefly discussed. For sandstone, the α values are steady at about 0.5, whereas for granite, the α values are not constant. But they all increase with stress increment. This result may be useful to the study of attenuation of seismic waves in the medium of earth.

关 键 词：内时理论 岩石衰减 应变振幅 平均应力 中等应变 非弹性参数 能量损耗 弹性模量 

分 类 号：P55[天文地球—构造地质学]