水和围压下片岩变形各向异性及其应用研究

Schist Deformation Anisotropy Affected by Water and Confining Pressure and Its Application

为探讨在不同应力条件和含水状态下,片岩变形各向异性变化特征及隧道围岩变形响应规律,制备α=0°、α=45°、α=90°三种代表性片理倾角的天然与饱和武当群片岩试样,采用三轴压缩试验分析在水和围压因素影响下,片岩弹性模量、泊松比等变形参数及变形各向异性演变特征。基于试验结果,建立隧道围岩的等效各向异性模型,模拟分析片岩变形各向异性与隧道围岩位移之间的变化关系。结果表明:片岩弹性模量、泊松比与围压呈正相关;饱和状态下,围压对变形各向异性有明显弱化作用;饱水后,片岩弹性模量减小而泊松比增大,变形各向异性有显著增强趋势;天然状态各向异性对围岩变形影响强于饱和状态;饱和状态下,随埋深增加,围岩变形对各向异性更趋敏感,而天然状态埋深对二者关系影响较小。

To investigate the deformation properties of surrounding rock of tunnel response to deformation anisotropy of schist in different stress and water content states,natural and saturated schist samples with three kinds of representative schistose angle,that is α = 0°、α = 45°、α = 90°,were processed. The triaxial compression test was carried out to investigate the evolution characteristics of deformation parameters as well as deformation anisotropy of schist under the condition of water and confining pressure. On the basis of the test＇s results,the tunnel models with equivalent anisotropic surrounding rock were built. Then,the relationship between deformation anisotropy and the displacement of tunnel surrounding rock was analyzed. The results show that elastic modulus and Poisson＇s ratio of schist are positive correlated with confining pressure and confining pressure obviously weakens deformation anisotropy of schist under the saturated condition. When water content increases,elastic modulus of schist with all kinds of schistose angle tends to reduce. However,the Poisson＇s ratio and the degree of deformation anisotropy increase significantly. In the natural state,the influence of anisotropy on the deformation of surrounding rock is more obvious relative to the saturated condition. In the saturated state,the change of deformation anisotropy is easier to cause the variation of the displacement of surrounding rock with the increase of depth. But in natural state,buried depth of tunnel has less effect on the response degree of the displacement of surrounding rock to deformation anisotropy of schist.