黄土洞室掘进深度与围岩位移变化规律研究

应用PLAXIS 2D/3D有限元分析软件,对某黄土洞室进行了二维、三维分步掘进、三维一次掘进等工况的弹塑性有限元分析,研究分析了不同工况下洞室围岩位移的变化规律,并对掌子面的空间效应进行了分析。分析结果表明,二维与三维分步计算的最终位移基本一致,可以用二维的计算结果来估算洞室开挖的最终位移。三维分步掘进的分析表明,不同埋深的洞室其位移比的变化规律基本一致,当L/B<1时(L为掘进深度,B为洞室跨度),位移比呈线性增加;当L/B>1时,位移比呈非线性增加;当L/B>3时,其最大位移接近最终位移。掌子面的空间效应分析表明,在掌子面处的位移约为最终位移的1/3,距掌子面0.5倍跨度处的位移约为最终位移的2/3,距掌子面2.5倍跨度处的位移基本达到了最终位移。

Variation Law of Excavation Depth and Surrounding Rock Displacement of Loess Cavern

The elastoplastic finite element analysis of a loess cavern was carried out by two-dimensional,three-dimensional step-by-step excavation and three-dimensional one-shot excavation using PLAXIS 2D/3D finite element analysis software.The variation law in displacement of surrounding rock of cavern under different working conditions is analyzed,and the spatial effect of the tunnel face is analyzed.The analysis results show that the final displacement of the two-dimensional and three-dimensional step-by-step calculations is basically the same.Therefore,the two-dimensional calculation results can be used to estimate the final displacement of the cavern excavation.The analysis of three-dimensional step-by-step excavation shows that the displacement development of underground caverns with different depths is basically the same.When L/B≤1(L is the tunneling depth and B is the tunnel span),the displacement ratio increases linearly.When L/B>1,the displacement ratio increases nonlinearly.When L/B>3,the maximum displacement is close to the final displacement.The spatial effect analysis of the tunnel face shows that the displacement at the tunnel face is about 1/3 of the final displacement.The displacement at a distance of 0.5 times span from the tunnel face is about 2/3 of the final displacement.The displacement at 2.5 times span from tunnel face is basically the final displacement.