含褶皱巷道围岩破裂碎胀大变形机理FDEM数值模拟研究

FDEM numerical simulation on buckling failure mechanism of surrounding rock masses containing folded structures

巷道频繁遭遇褶皱构造,采用有限元离散元耦合数值模拟方法(FDEM)研究含褶皱巷道围岩破裂碎胀大变形机理。首先改进了FDEM剪切应力峰后软化本构模型,使其在压剪应力状态下保持残余剪应力,随后采用余弦函数y=acos(x)建立不同形态的褶皱构造数值模型,最后采用改进的FDEM数值模拟程序研究了不同地应力侧压系数λ(λ=0.5、2.0)和不同褶皱形态下(a=0、0.5 m和1.5 m)的各向同性围岩体破裂碎胀大变形机理。结果表明,对于各向同性岩体,褶皱形态的影响微弱,均呈现X型共轭剪切破坏并伴随拉伸断裂,断裂块体沿剪切带的滑移剪胀及破碎块体的翻转大运动造成破碎岩块的体积膨胀,发生破裂碎胀性大变形。

The folded structures are frequently encountered in roadway excavation;therefore,the combined finite-discrete element numerical method(FDEM)was used in paper to study buckling failure mechanism of surrounding rock masses containing folded structures.Firstly,the FDEM shear stress constitutive model at post-peak softening stage was improved,in which the residual shear stress could be maintained under compression-shear state.Then,numerical models of folded structures with different shapes were established by using consie function y=acos(x).Finally,the improved FDEM numerical method was used to study the failure and large deformation mechanism of isotropic and anisotropic rock mass with different in situ stress lateral coefficientsλ(λ=0.5 and 2.0)and folded structure shapes(a=0,0.5 m and 1.5 m).The study results indicated that for the isotropic rock mass,the influence of folded structures shape was weak,that was,the rock mass was fracture by X-shaped conjugated shear cracks following by few tension cracks.The large deformation was induced by the buckling failure of rock mass and the movement of the rock fragments..