云南宣威群地层路堑边坡滑带土蠕变特性研究

Creep Properties of Sliding Zone Soil in Roadcut Slope of Xuanwei Formation Strata in Yunnan Province

为研究云南宣威群地层路堑边坡滑带土的蠕变特性,采用GDS非饱和反压直剪仪,对边坡滑带土进行直剪蠕变试验,研究该路堑边坡滑带土在不同法向应力下的蠕变特性和长期强度。试验结果表明:该路堑边坡滑带土的绝对蠕变量随水平剪切应力的增加而增加,当水平剪切应力一定时,滑带土的绝对蠕变量与法向应力呈负相关性,而滑带土的瞬时蠕变量随水平剪切应力的增加表现为先减小后增大;滑带土的长期黏聚力为14.00 kPa,长期内摩擦角为7.13°,与常规慢剪试验的滑带土的抗剪强度参数相比,滑带土的黏聚力和内摩擦角分别减少了56.5%和10.9%;采用Burgers-Kelvin蠕变模型对滑带土的蠕变试验数据进行了拟合,模型拟合的相关系数都在0.96以上,表明Burgers-Kelvin蠕变模型能够较好地反映该路堑边坡滑带土的蠕变特性。

In order to study the creep properties of sliding zone soil in roadcut slope of Xuanwei Formation in Yunnan Province, this paper studies the creep properties and long-term strength of sliding zone soil under different direction stress by GDS unsaturated direct shear apparatus.The experimental results show that the absolute creep of soil in slope sliding zone increases with the increase of horizontal shear stress.When the horizontal shear stress is constant, the absolute creep variable of the sliding zone soil is negatively correlated with the normal stress;with the increase of horizontal shear stress, the instantaneous creep of the sliding zone soil decreases first and then increases;the long-term cohesion of sliding-zone soil is 14.00 kPa, and the long-term internal friction angle is 7.13°.Compared with the shear strength parameters of the conventional slow shear test, the cohesion and internal friction angle are reduced by 56.5% and 10.9%,respectively.Using Burgers-Kelvin creep model to fit the creep test data, the correlation coefficients are all above 0.96,which indicates that Burgers-Kelvin creep model can better describe the creep characteristics of sliding zone soil.