巷道围岩变形破坏数值模拟

Numerical simulation of roadway surrounding rock deformation and destruction

为研究圆形巷道开挖之后,围岩中的剪切应变增量、最小主应力的分布与演化规律,基于包含界面及基体的颗粒体模型,考虑模型参数内聚力的软化行为,应用FLAC-3D软件,模拟出"V"形坑内发生层裂的破坏现象.结果表明:当模型参数脆性较低时,剪切应变增量高值呈条带状展布,彼此交叉,向围岩深部延伸;最小主应力出现高、低值相间隔现象.随着巷道尺寸的增加,剪切带的数目增多,长度增加;最小主应力高、低值相间隔现象加剧,间距无明显变化;随着围压的增加,剪切应变增量、最小主应力高值区在2个直径方向呈现更清晰的分布规律,当围压较高时,其模拟结果与现场观测到的"V"形坑内发生层裂的破坏现象更加吻合.

In the paper, the granular model which contains interface and matrix was introduced, considering the softening behavior of cohesion parameters. In the calculation of FLAC-3D, according to the evolution and distribution of shear strain increments, minimum principal stresses and in surrounding rock of a circular tunnel after excavation. The numerical simulation based on equilibrium shows that higher shear strain increments form an intersecting shear bands network and extends to the depth of the surrounding rock; the phenomenon of the regions with higher minimum principal stresses separated by the regions without higher minimum principal stresses, and the spacing is uniform. With an increase of the tunnel diameter, the number and length of shear bands increases; the annular regions with higher and lower minimum principal stresses get more obvious. At a high confining pressure,clear and ordered distribution of what mentioned above are found on diametrically apposite of the tunnel, and the results are similar to the zonal disintegration phenomenon found in situ.