【摘要】 以大跨度地下洞室开挖支护过程为背景,探讨使用显式有限元方法分析地下洞室分步开挖和喷锚支护过程的可行性。然后在此基础上分析地冲击荷载下大跨度地下洞室的动力响应问题。分析结果表明,不同的开挖和支护方案对洞室的最终位移状态影响不大,而对最终塑性应变的大小和空间分布的影响较大;施工过程中底板有明显的隆起。在给定埋深条件下,由于地冲击荷载作用引起的围岩塑性应变的增加变得不太明显,但是在荷载作用过程中锚杆的轴力变化很大,说明锚杆的支护作用在大跨度结构抗地冲击荷载作用时显得非常重要。更多还原

【Abstract】 Taking an actual large underground engineering for example,the feasibility of simulating the multi-step excavating,shotcrete and rock bolt supporting for deeply buried wide span tunnel is investigated by using the explicit finite element method.Then,the dynamic responses are investigated under ground shock by nuclear contact surface burst.The analytical results make clear that the programs of excavation and supporting have a large influence on the final plastic strain state of tunnel and a small influence on the displacement state;in addition,the obvious upswell exists on the bottom floor of surrounding rock.For applied depth of burial,the increasing of plastic strain is negligible for applied loading in surrounding rock.It is worthy of note that the axial force of bolts increase to a considerable degree during ground shock;the supporting effect of bolts is necessary to increase the groundshock-resistant ability for deeply-buried wide span tunnel.更多还原