强风化角岩力学-变形特性的直剪试验研究

Direct shear test for strength and deformation characteristics of highly decomposed hornfels

对深圳岭澳三期核电工程选址区域内的强风化角岩的直剪试验研究表明,强风化角岩的剪切变形存在一定的延性且呈塑性破坏,其岩体剪切强度随含水率的增长呈负指数下降趋势,水对岩体强度指标c、具有一定的弱化作用;强风化角岩在饱水条件下只发生剪缩现象,而天然条件下先剪缩后剪胀。引入剪切刚度研究直剪试验的变形特性并考虑水对这一变形指标的影响,研究认为,强风化角岩的剪切刚度随法向应力的增加而增加,且随含水率的增加而降低,低法向应力条件下对水的作用尤其敏感,同时分析了剪切刚度的变化对边坡岩体剪切位移的影响,其结果对边坡的稳定性分析及坡体位移变化的预测具有一定的指导作用。

Through the field shear test of highly decomposed hornfels at the site of LingaoⅢnuclear power project in Shenzhen,it is shown that the shear deformation of highly decomposed hornfels has some definite ductility.Its shear strength of highly decomposed hornfels decreases exponentially with the water content increase.The rock shear strength indices c and are weakened definitely by water.The natural hornfels has the characteristic of shear-thinning after dilatancy but saturated ones only shear-thinning during the experiment.We introduce the deformation index of shear stiffness to study the deformation characteristics of direct shear test and take the influence of water into account.It is shown that the shear stiffness increases with normal stress increase and decreases with its water content increase,especially in the condition of low normal stress.At the same time we analyse the influences qualitatively to the shear deformation with the changing shear stiffness,which has definite guidance for the slope stability analysis and the prediction of slope displacements.