层状含水页岩蠕变特性试验研究

为分析层理和水对页岩的蠕变特性影响，室内制取0°、30°、60°、90°和不含层理5种页岩，每种层理页岩均处理成干燥、自然、不饱水、饱水4种含水状态，对其进行单轴压缩下的蠕变试验。试验结果表明，（1）层理角度和含水率对页岩的蠕变特性均有较大影响。同一含水率下随层理角度的增大，页岩的初始瞬时弹性呈指数式减小，瞬时弹性模量成指数式增加。相同层理角度下，随含水率升高，页岩的初始瞬时弹性应变线性增长，瞬时弹性模量线性下降；（2）采用含有弹性元件、黏性元件及开尔文体的“伯格斯”蠕变模型对页岩的蠕变过程进行描述，并对模型的参数进行了反演和验证，表明该模型能够较好地反映页岩的蠕变特征。根据试验所得层理和水对页岩蠕变变形的影响规律，通过瞬时弹性模量和黏性系数与层理角度和含水率的拟合关系，将蠕变模型中的瞬时弹性模量和黏性系数替换为层理倾角和含水率的函数，构建了能够反映页岩层理和含水率的蠕变模型。

Experimental study of creep characteristics of layered water bearing shale

In order to analyze the influence of bedding and water on the creep characteristics of shale, five kinds of shale are prepared in the laboratory, including 0, 30, 60, 90 degrees and no bedding. Each kind of bedding shale is treated with 4 kinds of water bearing state, which is dry, natural, water unsaturated and water saturated. The results show that: (1) The bedding angle and water content have great influence on the creep characteristics of shale. At the same moisture content, with the increase of the angle of stratification, the initial instantaneous elasticity of shale decreases exponentially and the instantaneous elastic modulus increases exponentially. At the same layer angle, with the increase of moisture content, the initial instantaneous elastic strain linear growth of shale and linear decrease of instantaneous elastic modulus. (2) The creep of shale is described by Burgers creep model with elastic elements, viscous elements and Kelvin body, and the parameters of the model inversion and the verification. The results show that the model can better reflect the features of the shale creep. According to the law of the influence of the bedding and water on the creep deformation of shale and based on the fitting relationship between the instantaneous elastic modulus, the viscosity coefficient and the bedding angle, water content, the instantaneous elastic modulus and viscosity coefficient of the creep model are replaced by a function of the bedding angle and moisture content; thus a creep model which can reflect shale bedding and water content is constructed.