斜入射地震下预制拼装管廊地震响应分析

Response analysis for prefabricated composite utility tunnels under oblique incident earthquakes

斜入射相较于垂直入射存在着更为复杂的波场叠加情况,从而引起土体产生非一致性变化,而预制管廊等地下结构也相应地存在着更为复杂的响应,但目前该方面的认识仍不充分。因此,以某试验区环湖路综合管廊工程为背景,进行了斜入射下预制拼装管廊非线性地震分析方法和响应规律研究。首先介绍了土结共同作用的与预制拼装综合管廊有限元模型的建立方法,包括单元选择、土体动力本构和编程以及动力接触模拟等。重点研究了斜入射土体粘弹性边界的建立,并建立了Auto_VSB辅助程序,得到了预制拼装管廊的地震响应规律。结果表明,文中建立的模型能较好实现斜入射作用下预制拼装管廊的地震响应分析,其中,斜入射土体粘弹性边界具有较高的精度,辅助程序极大提高了计算效率。与垂直入射相比,斜入射条件下土底加速度传播至结构底部会被放大,竖向加速度放大系数增大,结构接头间竖向错动位移增大。斜入射输入方式在竖向对结构造成较大影响,在实际工程中应加以考虑。

Compared with vertical incidence,oblique incidence has a more complicated wavefield superposition,which causes inconsistent changes in the soil,and underground structures such as prefabricated composite utility tunnels also have correspondingly more complex responses.The awareness of it is still insufficient.Therefore,take the Pingtan utility tunnels project as the background,the nonlinear seismic analysis method and response law of the prefabricated utility tunnels under oblique incidence were studied.Firstly,it introduces the method of establishing the finite element model of the prefabricated and assembled utility tunnels,including unit selection,soil dynamic constitutive and programming,and dynamic contact simulation.The focus is on the establishment of the viscoelastic boundary of the obliquely incident soil,and the Auto_VSB auxiliary program is established,and the seismic response law of the prefabricated utility tunnels is obtained.The results show that the model established in this paper can better realize the seismic response analysis of the prefabricated utility tunnels under the oblique incidence.Among them,the viscoelastic boundary of the oblique incidence soil has high accuracy,and the auxiliary program greatly improves the calculation efficiency.Compared with vertical incidence,under the condition of oblique incidence,the acceleration of the soil bottom propagating to the bottom of the structure will be amplified,the vertical acceleration amplification factor increases,and the vertical displacement between structural joints increases.The oblique incident input method has a greater impact on the structure in the vertical direction,and should be considered in actual engineering.