多点输入下悬跨海底管道非线性地震响应参数分析

Nonlinear parametric analysis of free spanning submarine pipelines under spatially varying earthquake ground motions

建立悬跨海底管道多点输入非线性分析模型,讨论非线性因素对悬跨海底管道多点输入响应的影响,生成了具备局部场地收敛性的空间相关多点地震动时程。利用Morison方程得到悬跨海底管道所受的动水作用力,并进一步推导考虑动水作用力的悬跨海底管道多点输入动力方程。研究采用不同管道材料模型时,管道的多点输入响应随跨长和地震动强度的变化。分析几何非线性对管道多点输入响应的影响。讨论采用不同土体模型时管道多点输入响应的异同。结果表明,针对大跨度管道和强震作用的情况,应采用非线性管材模型用以反映管道的塑性变形情况;几何非线性特性对大跨度管道的多点输入响应影响显著,在进行大跨度管道的地震响应分析中必须加以考虑;考虑土体的塑性滑移后,管道的地震响应有所降低,在管道屈服后,土体特性对管道响应的影响不明显。

A nonlinear numerical model of a free spanning submarine pipeline subjected to spatially varying earthquake ground motions was established, and the effects of nonlinear factors on the seismic response of the pipeline were discussed. A group of local convergent multiple-station earthquake ground motions was simulated. The hydrodynamic force applied to the submarine pipeline was calculated by using the Morison＇s equation. The equation of motion for a submarine pipeline under multi-support seismic excitation was derived. Considering different constitutive models of pipe steel, the variation of seismic response with peak seismic acceleration and span length was studied. The effect of large displacement on the seismic response of the pipeline was analyzed. Different seismic responses of the pipeline due to different soil models were investigated. The results show that nonlinear pipe material model should be adopted to simulate the plastic deformation ＇of the pipeline in the case of long span and strong earthquake. The large displacement effect should be considered since it significaotly affects the multi-support exciting seismic response of the long span submarine pipeline. Before the pipe yields, the seismic response of the pipeline decreased when the plastic properties of the soil were taken into account. After the pipe yields, the soil model had little effect on the response of the pipeline.