饱水 －失水循环下泥岩的剪切蠕变特性研究

为研究滇中红层泥岩在饱水 －失水循环作用下的剪切蠕变特性，采用 YBL －300 剪切流变仪开展了剪切流变试验。试验结果表明: ( 1) 滇中红层泥岩在法向正应力较低时，饱水 － 失水循环下的泥岩蠕变剪应力相较于饱和状态与天然状态下的分别减少了74%与 79%; ( 2) 饱水 － 失水循环引起了剪切蠕变曲线中出现“台阶”现象，而在同一级蠕变曲线中，饱水 － 失水循环次数的增多，“台阶” 现象逐渐消失; ( 3) 法向正应力较小时，饱水 － 失水循环对泥岩的剪切蠕变特性影响较大，随正应力增大，影响逐渐减小; ( 4) 通过五元件粘弹性剪切蠕变模型和幂函数型经验模型构建了饱水 － 失水循环泥岩剪切蠕变应变 －时间线方程，并得出与试验相符的应变 －时间模拟线。

Study on shear creep behavior of mudstone under saturated-dehydrated cycling

In order to study the shear creep characteristics of red mudstone in Central Yunnan under the action of saturated water loss cycle，a shear rheometer is used to carry out relevant tests. The test results indicate that ( 1) when the normal stress of the mudstone of the red layer in the Middle Yunnan is low， the creep shear stress of the mudstone under the saturated water and water loss cycle decreases by 74% and 79% respectively，compared with the saturated state and the natural state; ( 2) the phenomenon of“step”in the shear creep curve is caused by the water satiety-water loss cycle，and in the same creep curve， the number of full water-water loss cycle increases，and the“step”phenomenon is gradually disappearing; ( 3) when the normal stress is small， the saturated water loss cycle has great influence on the shear creep properties of mudstone，and the effect decreases with the increase of normal stress; ( 4) by using the viscoelastic shear creep model of five elements and the power function model， the shear creep strain time line equation of the saturated water and water lost circulation mudstone is constructed，and the strain time simulation line which is consistent with the test is obtained.