This paper studies the effect of stress lower limit on deformation characteristics of muddy sandstones during cyclic loading under pore pressure. The cyclic loading tests with pore pressure were conducted including increasing, constant, and decreasing stress lower limits. The results indicate that the relationship between deviatoric stress and volumetric strain can be divided into four cases during cyclic loading. The increase in the stress lower limit could reduce the peak strength, accumulate the irreversible strain, and accelerate the failure of muddy sandstones. After failure, both the elastic modulus and Poisson's ratio decrease and fluctuate within a certain range.

中文翻译：

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孔隙压力下不同应力下限泥质砂岩循环加卸载变形特征

研究应力下限对泥质砂岩在孔隙压力作用下循环加载变形特性的影响。进行了孔隙压力循环加载试验，包括增加、恒定和减少应力下限。结果表明，在循环加载过程中，偏应力与体积应变之间的关系可分为四种情况。应力下限的增加会降低峰值强度，积累不可逆应变，加速泥质砂岩的破坏。破坏后，弹性模量和泊松比均下降，并在一定范围内波动。