中文摘要：

在三峡库区万州侏罗纪红层中,发育大量近水平滑坡,其成因一直存在争议。为揭示这些滑坡的形成机制,采用RLM–2000微机控制的岩石三轴蠕变试验机,在恒温条件下,对万州二层岩滑坡的砂岩进行蠕变试验。试样在破坏前经历约8h的加速蠕变阶段,这与现场观察到的近水平滑坡破坏变形特点非常相似。蠕变试验的等时曲线显示该砂岩流变具有较好的线性特征。采取Burgers模型对砂岩流变曲线进行辨识,推导Burgers模型的三维本构方程,并确定模型参数。结果表明,采用Burgers模型可以非常准确地描述该种岩石的流变特性,为探讨万州近水平滑坡的力学机制提供模型和参数。通过分析蠕变应变率–时间关系,发现在蠕变加速阶段初期,蠕变应变率随时间近似线性增长,在蠕变加速后期,蠕变应变随时间近似指数增长。红砂岩在加速蠕变过程中具有高度的非线性,蠕变应变率随时间呈现跳跃增长特性。同时试验结果还表明,该种岩石长期强度只有瞬时强度的0.44倍,这一结论对研究近水平滑坡的形成机制以及防治具有重要的指导意义。

英文摘要：

Many approximately horizontal slip surface landslides are found in Jurassic red strata in Wanzhou of the Three Gorges Reservoir area. However, the formation mechanism of these landslides is not clear. In order to discover the causes of these landslides, experiments on rheological behaviors were performed on the sandstone of Erchengyan landslide bedrock in Wanzhou with triaxial creep test machine RLM- 2000. Before the specimen failure, there is an accelerated creep stage, which lasts for about 8 h; this course is similar to the failure of deformation of some approximately horizontal slip surface landslides. Tautochrone of test data indicates this kind of rock is close to linear viscoelasto-plastic materials. Burgers model is used to fit the curves; and the three-dimensional constitutive relationship of Burgers model and its parameters are obtained. The results show that the proposed rheological Burgers model can exactly express the rheological characteristics of Jurassic red strata in Wanzhou. It can also describe the mechanism of the approximately horizontal slip surface landslides occurring in Jurassic red strata in Wanzhou. There is a nearly linear relationship between the creep strain rate and time in the beginning of accelerative creep stage. And the creep strain rate behaves closely to exponential growth with time in the last stage of accelerative creep. The accelerative creep shows highly nonlinear characteristics; and the creep strain rate displays a discontinuous form, which occurs in jumps change. Furthermore, the experimental results reveal the long-term strength of the rock is only 44 percent of the peak strength in triaxial tests. This conclusion is very helpful for the research on the mechanism and prevention of the horizontal slip surface landslides.