桥隧相连体系隧道洞口段动力响应研究

为了对桥隧相连体系隧道洞口段的抗震设计提供参考，通过大型振动台试验研究了桥隧相连体系隧道洞口段的破坏过程，并使用小波包变换对加速度响应信号进行了定量分析。研究结果表明：在地震动作用下，洞口段的破坏以拱顶边坡裂缝的产生为标志；桥隧相连体系中隧道洞口段不安全程度往往是拱顶最大，桥台次之，再而边坡，仰拱最小，但是实际工程中桥梁和隧道材料的强度和刚度相对较高，所以破坏往往先从坡体开始，然后才是拱顶和桥台部位，仰拱的破坏程度一般较小；低频成分（0.1～12.51 Hz）的地震波在洞口段边坡破坏过程中起主导作用，而且地震波从土体传播进入混凝土结构之前，由于不同材料界面处复杂的折射反射问题，低频成分会出现剧烈的变化；从低频成分能量占比变化的角度分析，洞口段边坡的破坏可分为3个阶段：小震作用下的弹性变形阶段，中震作用下的弹塑性小变形阶段，以及强震作用下的大变形破坏阶段。

Research on dynamic responses of the portal in bridge-tunnel connected system

In order to provide reference for the seismic design of the portal in the bridge-tunnel connected system, the failure process of the portal was studied through the large-scale shaking table tests, and obtained the acceleration signals which were quantitatively analyzed by wavelet packet transform. It is found that the failure of the portal is marked with the appearance of the crack in the vault slope. The unsafety degree of tunnel portal in the bridge-tunnel connected system ranks as the vault, the abutment, the slope and the invert in turns under the action of ground motion. The strength and stiffness of the bridge and tunnel are relatively high and therefore, the failure often starts from the slope, then the vault and abutment, while the damage of the invert is generally slight. The seismic wave with a low-frequency (0.1?12.51 Hz) plays a leading role in the failure process of the portal-slope system. Due to the complex refraction and reflection effect between the different material interfaces, the low-frequency waves will change drastically before propagating from soil into concrete structures. By analyzing the changes in the percentage of the energy of the low-frequency waves, the failure of portal-slope system can be divided into three stages, i.e., the elastic deformation stage under the small-shake, the small elastic-plastic deformation stage under the medium-shake, and the large failure deformation stage under strong-shake.