The authors examine Kaiser effect in sandstone in nonproportional triaxial cyclic compression tests with stage rotation of an assigned stress ellipsoid through an angle of 90°. The load program consists of three pairs of cycles such that the maximal nominal stress of the second cycle exceeds the first cycle stress by 20 MPa at the constant side support. Cyclic loading is applied to sandstone in three orthogonal directions, with two cycles in each direction. Kaiser effect only appears in the second loading in the same direction, and activation of acoustic emission upon the change in the active loading direction is independent of the earlier reached stress level. This fact points at the orientation-driven nature of Kaiser effect, which means the material remembers its lattermost internal damaged structure.

中文翻译：

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砂岩中的凯撒效应在多轴压缩中指定应力椭球的多级旋转

作者在非比例三轴循环压缩试验中检查了砂岩中的 Kaiser 效应，其中指定应力椭球通过 90° 角的阶段旋转。加载程序由三对循环组成，这样在恒定侧支撑处，第二个循环的最大标称应力超过第一个循环应力 20 MPa。在三个正交方向上对砂岩施加循环载荷，每个方向有两个循环。Kaiser 效应仅出现在相同方向的第二次加载中，并且主动加载方向改变时声发射的激活与先前达到的应力水平无关。这一事实表明了凯撒效应的方向驱动性质，这意味着材料会记住其最后的内部损坏结构。