方向性脉冲型地震动对沉管隧道动力响应分析

为揭示地震动的脉冲效应对沉管隧道动力响应的影响,参考广州佛山沉管隧道建立了一个双向四车道沉管隧道动力分析有限元模型。动力有限元模型中引入了土体的非线性动力本构模型,通过在模型底部水平向输入地震动,对比分析了40组具有方向性效应脉冲型地震动(FD)及相应剔除速度脉冲后的无脉冲地震动(NP)作用下沉管隧道的地震响应。研究结果表明:(1)FD地震动相对于NP地震动对沉管隧道的响应更大(位移、加速度及应力);(2)随着地震动峰值速度(PGV)的增大,结构的响应也都呈现出增大的趋势,同时峰值速度影响系数R较大时,相对应的结构响应脉冲影响系数K也大,说明具有速度脉冲的地震动对结构的响应更大;(3)随着脉冲周期T_p的增大,结构响应的脉冲影响系数K都是先增后减,并且脉冲周期在结构第一自振周期附近区间时,结构响应都较大,说明脉冲型地震动的脉冲周期对沉管隧道的地震响应也有显著影响。

Response Analysis of Directional Pulse Type Ground Motion to Immersed Tunnel

In order to reveal the influence of the pulse effect of ground motion on the dynamic response of the immersed tunnel, a finite element model for the dynamic analysis of a bi-directional four-lane immersed tunnel was established based on the Foshan immersed tunnel structure in Guangzhou. The nonlinear dynamic constitutive model of soil was introduced into the dynamic finite element model, and the seismic responses of 40 groups of forward directional pulse ground motions (FD) as well as the corresponding non pulse ground motions (NP) with velocity pulse excluded were compared and analyzed by inlaying ground motions horizontally at the bottom of the model. The results show that: (1) the response of FD ground motion of immersed tunnel is larger than NP ground motion (displacement, acceleration and stress); (2) with the increase of PGV of ground motion, the structural responses also show an increasing trend. At the same time, the corresponding influence coefficient K of structural responses pulse is large when the influence coefficient R of peak velocity is large, indicating that the ground motion with velocity pulse has a greater response to the structure; (3) with the increase of pulse cycle T_p,structural responses of pulse influence coefficient K increased at first and then decreased, Moreover the structural responses are larger when T_p performed in the interval near the first natural vibration period of the structure, The damage performed similarly showed that there was significant influence of pulse period of pulsed ground motion on the seismic response of the immersed tunnel.