基于三轴压缩循环加卸载试验结果,对黄砂岩峰值强度、变形特征、弹性模量、能量转化和阻尼比变化规律开展了试验研究。结果表明:随着围压的增大,黄砂岩峰值强度满足线性增长的关系;而循环荷载对黄砂岩峰值强度影响较小。通过弹塑性应变分离,发现弹塑性应变量和弹塑性应变占比在岩石破坏的循环次数里存在陡变情况;在0~20 MPa围压下,黄砂岩加卸载弹性模量随围压增大而增大,当围压>20 MPa时,围压对黄砂岩加卸载弹性模量的影响变小。利用有限差分的方法计算了黄砂岩应变能、耗散能和阻尼比,得出耗散能随着循环次数增加先增加后减小,而阻尼比随循环次数增加先减小后增大,然后不断减小,最后趋于定值。研究成果可为黄砂岩工程应用提供一定的理论依据。
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.
关键词
黄砂岩 /
循环加卸载 /
弹性模量 /
能量演化 /
阻尼比
Key words
yellow sandstone /
cyclic loading and unloading /
elastic modulus /
energy evolution /
damping ratio
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