复合交通荷载下叠合式公轨合建隧道动力响应

叠合式公轨合建隧道不同于其他公轨合建隧道，汽车-列车荷载作用下其动力响应也有所不同。为研究复合交通荷载下叠合式公轨合建隧道动力响应，用激振力法、元胞自动机、汽车动力模型模拟列车荷载、车流和汽车荷载，用有限元软件Plaxis3D分析了不同荷载及有无垫层工况下隧道的动力响应。结果表明：公路隧道、铁路隧道分别主要对汽车荷载、列车荷载产生加速度响应，铁路隧道的加速度响应要明显大于公路隧道，约为后者的20倍；隧道不同位置处，对两种交通荷载的应力响应情况不同，铁路隧道应力响应主要受列车荷载控制，但当公路隧道中有大型车辆通过时，会对铁路隧道应力响应产生较大影响，甚至起到主导作用；公路、铁路隧道之间设置垫层会增大公路隧道的动力响应，但同时会减小公路隧道下方土层的刚度差异进而减小其应力值，综合作用下，设置垫层后公路隧道的应力状态会有所改善。

Study on Dynamic Response of Composite Highway - Rail Tunnel under Combined Traffic Load

The composite joint tunnel is different from other public rail tunnel, and its dynamic response is also different under vehicle and train load. In order to study the dynamic response of the composite joint tunnel under the composite traffic load, the excitation force method, cellular automata and vehicle dynamic model were used to simulate the train load, vehicle flow and vehicle load, and the finite element software Plaxis3D was used to analyze the dynamic response of the tunnel under different loads and with or without cushion. The results show that the acceleration response of highway tunnel and railway tunnel is mainly to vehicle load and train load, respectively. The acceleration response of railway tunnel is significantly greater than that of highway tunnel, which is about 20 times of the latter. At different locations of the tunnel, the stress response of the two traffic loads is different. The stress response of the railway tunnel is mainly controlled by the train load, but when large vehicles pass through the highway tunnel, it will have a great influence on the stress response of the railway tunnel, and even play a leading role. Setting cushion between highway and railway tunnels will increase the dynamic response of highway tunnels, but it will also reduce the stiffness difference of the soil below the highway tunnel and then reduce its stress value. Under the combined effect, the stress state of highway tunnels will be improved after setting cushion.