软弱泥化夹层蠕变特性试验研究

Experimental study on creep characteristics of soft and weak muddied interlayer

软弱泥化夹层作为软硬相间岩体中存在的一种特殊薄层,其剪切蠕变特性常常是诱发边滑坡失稳的关键因素。因此,采用改进的应力式直剪仪,以梯级加载方式对软弱泥化夹层试样进行剪切蠕变试验。研究结果表明:软弱泥化夹层试样具有显著的蠕变特性,在各级剪应力作用下,试样经历了瞬时变形、衰减蠕变和似稳态蠕变3个阶段;随着时间的推移,土体的蠕变速率逐渐减小并最终趋于某一稳定值,而当剪应力水平达到剪切破坏强度时,土体发生破坏,蠕变速率出现激增现象;等时应力-应变曲线呈现出土体的非线性蠕变特性,当剪应力水平较低时,曲线呈现近似线性变化,而随着剪应力水平的逐渐增大,其非线性蠕变特征越来越明显。

As a special thin layer in the soft and hard rock, the shear creep property of the soft and muddied interlayer is often a key factor to induce the instability of the slope. Therefore, an improved stress-type direct shear instrument is used to conduct shear creep tests on soft muddied interlayer specimens with a stepped loading method. The results show that: the weak muddied interlayer specimens have significant creep characteristics, and under the action of shear stress at all levels, the specimens experience three stages of transient deformation, decay creep and seemingly steady state creep;the creep rate of the soil gradually decreases with time and finally tends to a stable value, and when the shear stress level reaches the shear damage strength, the soil is damaged and the creep rate appears to surge;the isochronous stress-strain curve shows the nonlinear creep characteristics of the soil, and when the shear stress level is low, the curve shows an approximately linear change, while with the gradual increase of the shear stress level, its nonlinear creep characteristics become more and more obvious.