雪峰山隧道砂板岩各向异性力学特性的试验研究

Experimental study of anisotropically mechanical characteristics of sandy slate in Xuefeng mountain tunnel

利用MTS815 Flex GT岩石力学试验系统,对雪峰山隧道围岩中的砂板岩开展单轴和三轴试验,研究这种砂板岩中的细微层理对岩石变形特性、强度特性及其参数的影响,结果表明:岩石力学特性的各向异性特征显著。层理面与轴向力夹角0°时应力-应变曲线呈不稳定破裂特征,破坏面沿层理面方向发育;夹角90°时曲线呈峰后迅速软化特征,破坏面为对角贯通性剪切破坏。单轴试验中夹角0°的抗压强度比夹角90°高出约20%,弹性模量和变形模量比夹角90°分别约大50%和80%。三轴试验中2种夹角情况破坏时主应力差(σ1?σ3)max相近,夹角0°的弹性模量和变形模量分别比夹角90°时约大6%和20%,围压对砂板岩的各向异性特征有弱化效应。这些结论揭示了该砂板岩各向异性的力学特性,对解决工程实际问题有重要的参考价值。

The sandy slate samples are taken from the Xuefeng mountain tunnel rock.To study the effect of micro-bedding on strength properties and deformation characteristics of samples,a series of uniaxial and triaxial compressed tests are carried out with MTS815 Flex GT rock mechanics test system.The experiment results show that mechanical properties of the rock is obvious anisotropy.The stress-strain curves display unstable broken feature when the bedding parallels to axial stress（angle 0°） and failure faces development along the bedding.Softening rapidly happened after peak when the bedding is perpendicular to axial stress（angle 90°） and failure faces belongs to shear failure.The numerical results of uniaxial test show that compression strength,elastic modulus and deformation modulus of angle 0° is 20%,50% and 80% higher separately than them of angle 90°.The results of triaxial test show the principal stress difference of them is close in the peak intensity;elastic modulus and deformation modulus of angle 0° is 6% and 20% higher than them of angle 90°.Confining pressure of triaxial tests has weakening effects on anisotropic features of the sandy slate.These conclusions reveal the sandy slate possesses anisotropic mechanical properties and offers important reference to solve practical engineering problems.