岩石结构面抗剪强度MTS三轴试验方法研究

A Method of Determining Shear Strength of Rock Discontinuities Through Triaxial Test

尝试在电液伺服岩石试验系统(MTS)上对无充填岩石节理试件进行三轴试验,该试验方法可利用一个结构面试样获得多组抗剪强度数据,克服了结构面直剪试验取样困难、试验结果离散性大等缺点,方法更为简单、快速。在此基础上,除对每一试件的试验结果按线性Mohr-Coulomb准则获得摩擦角和内聚力外,还对比分析了线性Mohr-Coulomb准则拟合、幂函数拟合和非线性Barton公式拟合结果,并对提出的试验方法进行了可靠性验证,最后分析了试验方法的适用范围。幂函数拟合和Barton公式拟合能够反映岩石节理剪切强度的非线性特征,优于Mohr-Coulomb准则;当 0.01 <σ nj /JCS< 0.3 时,幂函数拟合和Barton公式拟合岩石结构面剪切强度比较可靠,而当σ nj /JCS> 0.3 时获得的剪切强度偏高。

A simple and rapid method of triaxial test on non-filled rock specimens containing irregular discontinuities by using rock mechanics test system (MTS) is presented in this paper. Multiple shear strength data can be obtained by using this method in the presence of only one single specimen. The difficulty of preparing test specimen is overcome and the highly discrete test results can be avoided. In addition, approaches to determine the parameters of linear Mohr-Coulomb criterion fitting, power function fitting and nonlinear Barton equation fitting according to test results are examined and the results of different approaches are compared to verify the rationality of the method. The application scope of the test method is also put forward. Results suggest that power function fitting and nonlinear Barton equation fitting are superior to Mohr-Coulomb criterion in reflecting the nonlinearity of shear strength of jointed rock. When 0.01 <σ nj /JCS< 0.3 , the result of shear strength of jointed rock obtained by the two fitting methods are reliable;when σ nj /JCS> 0.3 , the result is larger.