高烈度地震区公路隧道洞口段地震响应分析

Seismic Response Analysis for a Highway Tunnel Portal Section in High-intensity Seismic Region

根据隧道地震安全性评价报告和地勘资料,建立了三维数值计算模型并采用一致粘弹性人工边界模拟动力边界,对高烈度地震区公路隧道洞口段进行了瞬态动力计算。计算结果表明:在三向地震荷载激励下,洞口段衬砌的地震响应具有明显滞后性,衬砌以水平横向振动为主、轴向振动次之、竖向振动最弱;洞口段衬砌的拱腰部位将承受极大拉应力和剪应力,可设减震层吸收地震能量。通过对衬砌相对位移的分析得出,衬砌横向和轴向变形都很小,衬砌稳定性尚好。

According to the report of seismic safety evaluation and the geological exploration data of the tunnel, a three-dimensional numerical model was established incorporating viscous-spring artificial boundaries and transient dynamic analysis was performed for the highway tunnel entrance in the region with high-intensity earthquake. Results showed that the seismic responses of the lining at the tunnel entrance lagged far behind the three dimensional seismic load. Horizontal vibration of lining was most obvious, while axial vibration as well as vertical vibration were the weakest. Arch-waist of the lining will sustain large tensile stresses and shearing stresses, shock absorption layer can be put behind the lining at this part to damp the seismic energy. Transverse and axial deformations of the lining were small through the analysis, the lining was stable.