关键词: 黄砂岩, 循环加卸载, 弹性模量, 能量演化, 阻尼比

Abstract: The variation rules of peak strength, deformation characteristics, elastic modulus, energy conversion and damping ratio of yellow sandstone were studied based on triaxial cyclic loading and unloading compression test. Experimental results revealed a linear relation between peak strength and confining pressure, while the cyclic load had little effect on the peak strength of yellow sandstone. Axial strain was separated into elastic strain and plastic strain, and the value and the proportion of elastic strain and plastic strain both changed abruptly in the cyclic loading process. Within the loading range of 0-20 MPa, the elastic modulus of yellow sandstone augmented with the climbing of confining pressure, whereas when confining pressure exceeded 20 MPa, the influence of confining pressure alleviated. Furthermore, the strain energy, dissipated energy and damping ratio of yellow sandstone were calculated using finite difference method, and results unveiled that with the proceeding of cyclic loading, the dissipated energy expanded first but then withdrew, while damping ratio was in an opposite trend until reaching a stable value.

Key words: yellow sandstone, cyclic loading and unloading, elastic modulus, energy evolution, damping ratio