大连湾海底沉管隧道南岸段及风塔结构抗震分析

为研究大连湾海底沉管隧道南岸段及风塔结构在地震作用下的内力规律及弹塑性阶段的损伤破坏特点，建立沉管-厂房-风塔三维精细化模型，采用ABAQUS自带的混凝土损伤本构模型，通过振型分解反应谱法及时程分析法开展两种地震工况下结构的地震响应分析。结果表明：(1)在设防地震作用下，X向和Y向位移最大值分别为1.11 mm和5.56 mm,均出现在结构通风塔顶端；(2)X方向和Y方向的振型参与质量系数分别为90.52%和92.07%,均满足抗震规范要求，且沉管隧道两车道连接部位的弯矩最大，为5 069 kN·m;(3)在罕遇地震下，结构最大层间位移角为1/2 798,结构的损伤最大值均发生地震波峰值时刻；由损伤情况可以看出，结构的混凝土均未出现压坏的现象，最大拉伸损伤系数为0.893～0.94,出现的部位为新风道及新风机房的顶板。因此，需要在沉管隧道两车道连接部位增强抗弯能力，在新风道及新风机房的顶板部位增加配筋，以增强抗拉能力。

Seismic analysis of the south bank section and wind towerstructures of Dalian Bay subsea immersed tube tunnel

In this paper, the internal force law of the south bank section and wind tower structure of Dalian Bay subsea immersed tube tunnel under the action of earthquakes and the structural damage characteristics in the elastoplastic stage were studied. In addition, a three-dimensional refined model of an immersed tube-plant-wind tower was established, and the ABAQUS built-in constitutive model of concrete damage was used to perform seismic response analysis of the structure under two seismic conditions using mode-superposition response spectrum and time-history analysis methods. Results show that the maximum displacement values in the X and Y directions are 1.11 and 5.56 mm, respectively, both appearing at the top of the structural ventilation tower. Moreover, the modal mass participation coefficients in the X and Y directions are 90.52% and 92.07%, respectively, both meeting the requirement of seismic code, and the bending moment at the junction of two lanes of the immersed tunnel is the largest, reaching 5 069 kN·m. Under rare earthquakes, the maximum story drift ratio of the structure is 1/2 798, and the maximum damage of the structure appears at the time of seismic wave peak. By observing the damage, the structural concrete is uniform, and no broken phenomenon is observed. The maximum tensile damage coefficient is 0.893-0.94, appearing at the fresh-air duct and roof of the fresh-air room. Therefore, enhancing the bending resistance at the connection between the two lanes of the immersed tunnel and adding reinforcement at the top plate of the fresh-air duct and fresh-air room are necessary to improve the tensile capacity.