考虑应变软化的地下采场开挖变形稳定性分析

Deformation and stability analysis of underground stope after excavation considering strain softening

为了分析某大型地下采场开挖稳定性,利用FLAC3D同时考虑岩土体的应变软化特性,计算开挖过程中的变形和破坏情况。结果表明:随着开挖的进行,周围岩体的位移不断增大,开挖步1_3,2_3和4引起的位移增量最大;开挖步1_1～1_2引起主采场顶板破坏高度为40m左右,当开挖步为1_3时,顶板破坏高度达到80m左右;2_1和2_2开挖步引起的破坏区面积变化不大,而2_3开挖步引起破坏高度迅速增长,达到120m;开挖到第4步时,由于主采场与1和2采场空区相互贯通,破坏高度同样迅速增大,达到150m左右;此后,由于影响稳定性的开挖阶段结束,破坏高度增量减小,最终破坏高度为160m左右,得到的结果能够为工程实践提供指导。

In order to study the three dimensional stability of one large underground stope after excavation, the numerical software FLAC^3D was used to simulate the deformation and failure situation of the surrounding rock mass. The characteristics of strain softening were considered during calculation. The calculation results show that during the procedure of excavation, the displacements of surrounding rock mass increase gradually, the excavation steps of 1_3, 2_3 and 4 lead to the largest increment of displacement; the failure height of stope after excavation steps of 1_1-1_2 is about 40 m, while the excavation of 1_3 leads to the failure height of 80 m. The excavation steps of 2_1 and 2_2 lead to few increments of displacement, while the 2_3 excavation step leads to great increment of displacement, which is 120 m displacement for this excavation step. The main stope and 1, 2 stopes connect with each other after the fourth excavation step, which leads to the great increase of plastic zone areas, and the height of failure is about 150 m. Then after the fourth excavation step, the displacement increment is small for the same step. That is because the excavation step which can influence the stability of gob areas has finished. At last, the failure height reaches about 160 m. The results obtained from calculation can give guidance to the real practice.