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用西原模型描述双重孔隙-裂隙介质的流变特性,在理论上给出了其流变参数及强度指标的确定方法,建立了瞬弹-黏弹-黏塑性平面有限元求解格式和研制了相应的计算程序。针对一个矩形地下洞室围岩为裂隙岩体和完整岩体的两种工况进行数值分析,对比了围岩中的位移、应力及塑性区。其结果显示:相比于单一介质的情况,双重介质因其变形模量、凝聚力和内摩擦角减小,故洞室围岩中随时发展的位移和塑性区有明显的增长,两种工况的围岩应力分布亦存在较大的不同,特别是双重介质围岩中最大主应力σ_1和最小主应力σ_3的差值较大,因此,提高了围岩破坏的可能性。
Using the Nishihara model to describe the rheological properties of the double porosity-fractured media, the rheological parameters and the determination of the strength index are given theoretically. The solution format of the instantaneous viscoelastic viscoelastic-viscoplastic planar finite element is established and correspondingly developed Calculation procedures. Aiming at the two kinds of working conditions of surrounding rock of a rectangular underground cavern as fractured rock mass and intact rock mass, the displacement, stress and plastic zone in surrounding rock are compared. The results show that compared with the single medium, the displacement and plastic zone of the surrounding rock in the cavern are obviously increased due to the decrease of the deformation modulus, cohesion and internal friction angle of the double medium. In both cases There is a big difference in the stress distribution of the surrounding rock. Especially, the difference between the maximum principal stress σ_1 and the minimum principal stress σ_3 in the double medium surrounding rock is large, thus increasing the possibility of surrounding rock failure.