爆破作用下拱顶衬砌脱空对隧道结构安全的影响分析

Analysis for impact of structural safety of tunnel induced by cavity on vault of lining under blasting

在对某隧道衬砌病害检测的基础上,研究该隧道衬砌在拱顶背后有脱空缺陷的情况下受邻近隧道爆破施工振动的影响。根据工程实况,运用ANSYS/LS-DYNA软件建立三维模型,模拟分析衬砌拱顶脱空高度分别为0,10,50和100 cm 4种工况下,隧道脱空区域和衬砌结构上质点振动速度峰值及主应力的分布特征。模拟分析结果表明:衬砌拱顶脱空的存在能减弱空洞周边质点在X方向上的振动速度峰值,增大Y方向的振动速度峰值;脱空区域质点Y方向上振动速度峰值比X方向的振动速度峰值变化大;衬砌拱顶脱空明显影响衬砌拱顶及迎爆侧拱肩的振动速度峰值和最大主应力的分布变化。当衬砌拱顶脱空高度达到某一特定值(如50 cm)时,对既有隧道衬砌结构的动力响应影响达到最大程度。

Based on the defect detection of a tunnel lining, the impact of the tunnel lining with defects （e.g cavity on the vaults of the lining） induced by nearby tunnel blasting vibration was studied. According to the engineering situation, a 3D model for the numerical simulation was established by the ANSYS/LS-DYNA software. The peak particle vibration velocity （PPV） and the maximum principal stress distribution at the situation of cavity area and the lining structure were analyzed respectively under the conditions that the values of the height of the cavity on the vaults of lining are 0, 10, 50 and 100 cm. The simulation results show that cavity on the vault of the lining can weaken the X direction of PPV and increase the Ydirection of PPV of the surrounding particles; the value of the Ydirection of PPV changes more than that of X direction of PPV of the particle around the cavity areas of the lining; the impact of the distribution of PPV and the maximum principal stress on the vault of the lining and the shoulder of the lining toward the blasting side induced by the cavity on the vault of lining are very obvious. The influence of the lining dynamic response of the existing tunnel lining comes up to the maximum when the height of the cavity on the vaults of the lining increases up to a certain value （such as 50 cm）.