不同含水条件下板岩力学实验研究与理论分析

以南水北调西线的板岩为研究对象，进行了不同泡水条件下的三轴压缩实验，通过引入相对吸水率的定义，分析了吸水率变化对岩石强度、弹性模量及泊松比等力学参数的影响，并从微观的角度分析了试样发生变化的机理，得出如下结论：(1)板岩在泡水后三轴抗压强度发生降低，最大降低辐度达46 %左右，抗压强度随相对吸水率的变化可以用函数式来有效的描述；(2)在泡水后，板岩的弹性模量与泊松比随着吸水率的增大而增大，但由于板岩自身各向异性明显，规律性不是特别明显，只能近似用关系式来模拟；(3)理论分析证实：实际泡水条件下的岩样，在受力挤压后，会经历排水与不排水两种过程，随着吸水率的提高，弹性模量与泊松比增大，验证了实验结果；(4)利用微观力学模型初步证实：泡水后板岩颗粒的吸水性与颗粒间毛细管力的减小是造成板岩泡水后发生软化的原因。

Experimental study and theoretical analysis of slates under different saturated conditions

Triaxial compression experiments of slates under different saturated conditions were done through the XTR01 electric- fluid serving compression machine, which were taken from the engineering of the western route of Water Transfer from South to North China. Relative saturation was defined as the ratio of mass of natural saturated rock to complete saturated rock; and the saturation was used to analyze the change of mechanical parameters (rock strength, elastic modulus and Poisson’s ratio). And an attempt was made to explain the change mechanism by the micro-mechanics model. With all the efforts, some conclusions are drawn as follows: 1)the triaxial compression strength of slates fell down when saturated in water and the most descendent can be 46%; and this change can be described by a law with the relative saturation; 2)when saturated, the elastic modulus and the Poisson’s ratio increased with the accretion of the relative saturation, but the law was not too clear for the anisotropy of the slates; 3)theoretical analysis has proved that the saturated rocks in geology conditions will undergo two process as drained and undrained, when the saturation increased, the elastic modulus and the Poisson’s ratio will increase simultaneously, which has confirmed the experiment results; 4)the micro-mechanical model shows that, when saturated in water, the absorbtion of the slate surface and the decrease of the capillarity among the grain are the main reasons to the water-weakening effect appeared in the slates.