不同强弱组合下岩-煤-岩串联模型的破坏特征(英文)

Failure characteristics of three-body model composed of rock and coal with different strength and stiffness

针对不同强度煤、岩单元建立4种不同强弱组合的岩-煤-岩三元体串联模型。通过对强-弱交界面的应力状态分析,建立交界面附近区域强、弱体的三轴压缩强度;基于三维快速朗格朗日元法,强、弱体均采用Coulomb-Mohr剪切破坏和拉伸破坏的复合应变软化模型,数值模拟4种不同组合三元体模型在不同围压下的应力-应变曲线特征,分析不同组合的剪切破坏带及塑性破坏区随围压的变化趋势。结果表明:强-弱组合体交界面的层间约束作用会派生出附加应力,导致交界面附近区域强体强度变弱,弱体强度增强;弱胶结软岩体和煤体在单轴压缩下呈现拉剪破坏,表现出明显的应变软化行为,随着围压的增大,拉伸破坏消失,向整体剪切破坏发展,但不同组合下的破坏带数目及破坏区域不同。该研究对地震、岩爆、矿山冲击地压等灾害机理研究具有重要指导意义。

Four different types of three-body model composed of rock and coal with different strength and stiffness were established in order to study the failure characteristics of compound model such as roof-coal-floor. Through stress analysis of the element with variable strength and stiffness extracted from the strong-weak interface, the tri-axial compressive strength of the weak body and strong body near the interface as well as the areas away from the contact surface was found. Then, on the basis of three-dimensional fast Lagrangian method of continua and strain softening constitutive model composed of Coulomb-Mohr shear failure with tensile cut-off, stress and strain relationship of the four three-body combined models were analyzed under different confining pressures by numerical simulation. Finally, the different features of local shear zones and plastic failure areas of the four different models and their development trend with increasing confining pressure were discussed. The results show that additional stresses are derived due to the lateral deformation constraints near the strong-weak interface area, which results in the strength increasing in weak body and strength decreasing in strong body. The weakly consolidated soft rock and coal cementation exhibit significant strain softening behavior and bear compound tension-shear failure under uni-axial compression. With the increase of confining pressure, the tensile failure disappears from the model, and the failure type of composed model changes to local shear failure with different number of shearing bands and plastic failure zones. This work shows important guiding significance for the mechanism study of seismic, rock burst, and coal bump.