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现有岩体爆破破碎理论中,临空面都发挥着极为重要的作用,利用临空面的破岩作用来达到降震的目的成为研究的重点。然现有研究多是理论探讨和现场试验,数值模拟方面鲜有涉及。本文采用LS-DANY有限元程序,定量分析了不同临空面数量时隧道结构的爆破震动响应,从数值上探讨了临空面对隧道爆破震动响应的影响机理;并结合西康二线小瓢沟隧道爆破开挖施工时既有大瓢沟隧道的振速实测数据,验证了数值模拟的合理性。研究结果表明,隧道爆破开挖施工中临空面的合理构造可有效降低既有结构的震动响应,所得结论亦可为新建隧道钻爆施工方案的优选提供理论依据。
In the existing theory of rock mass blasting and crushing, the surface of the freeboard plays an extremely important role. The purpose of using the broken rock of the freeboard to achieve the seismic reduction becomes the focus of the research. However, most of the existing researches are theoretical discussions and field experiments, which are rarely involved in numerical simulation. In this paper, the LS-DANY finite element program is used to quantitatively analyze the blasting vibration response of tunnel structures with different numbers of facing faces. The mechanism of the impact of the heading plane on the vibration response of the tunnel blasting is discussed numerically. In the blasting excavation, the measured data of the vibration velocity of the tunnel in Dalapugou are both validated the rationality of the numerical simulation. The results show that the reasonable construction of the temporary free surface in tunnel blasting excavation can effectively reduce the vibration response of the existing structure. The conclusion can also provide theoretical basis for the optimization of drilling and blasting construction schemes in new tunnels.