节理岩体各向异性等效弹性参数研究

Study of anisotropic equivalent elastic parameters of jointed rock mass

采用复合材料力学分析方法,针对规则节理岩体考虑坐标转换及刚度系数,建立各向异性等效弹性参数的解析公式。通过算例证明了解析公式的可行性,同时对规则节理岩体等效参数规律性进行了研究,分析在不同的节理刚度比值下等效弹性参数的变化规律。结合白鹤滩坝址区柱状节理岩体特征,探讨了其等效弹性参数取值和各向异性特征。研究表明:所采用方法在刚度取值相等时岩体可退化为各向同性介质,且该方法计算结果与实测结果较为吻合;同时发现柱体偏转对等效弹性参数的影响较大,偏转后水平向和铅直向弹性模量分别降低约54%和17%,根据曲线规律性,偏转角度越大,降低程度越高,等效弹性参数的曲线变化反映了其具有明显的各向异性特征。

Analytical formulas of anisotropic equivalent elastic parameters are established by using mechanical method of complex material. An example is made to show the feasibility and efficiency of the analytical formulas. Meanwhile, the coordinate transformation and jointed factor of regular jointed rock mass are considered. The rules of equivalent elastic parameters of regular jointed rock mass are studied. Variation rules of equivalent elastic parameters under different jointed factors are analyzed. Combining with the properties of columnar jointed rock mass in Baihetan dam site, the anisotropic characteristics and values of elastic parameters are analyzed. The results show that the jointed rock mass can degenerate into isotropic medium when the stiffness is equal; and the calculated values by using the method in the paper are well in accord with the test results in the dam site. The cylinder deflection has more effect on the equivalent elastic parameters. The results also show that after deflection, the horizontal elastic modulus and vertical modulus are reduced by 54% and 17% respectively. According to the curves, the higher the angle of cylinder, the greater reduction the elastic modulus would have. This change rule of equivalent elastic parameters revealed obvious anisotropic property of columnar jointed rock mass.