基于规范反应谱的码头岸坡地震永久变形计算

由于岸坡地震永久变形是造成码头结构破坏的重要原因之一,因而验算码头岸坡永久变形是码头抗震设计的重要内容。Newmark刚性滑块位移法由于其便捷性在永久变形计算中得到广泛应用,目前已提出的基于天然强震记录的Newmark滑块位移经验计算式,不针对具体场地,主要用于区域性地震滑坡危险性分析。以《水运工程抗震设计规范》中的设计反应谱作为目标谱,生成了不同峰值加速度、适合于不同类型场地的人工加速度地震波;采用Newmark滑块位移分析方法,通过对加速度时程中超过屈服加速度的部分进行二次积分,得到了不同类型场地、不同峰值地震加速度下对应于不同屈服加速度时的滑块位移,对位移计算结果进行回归得到码头岸坡永久变形的简化计算式。另外,通过参考国外的相关规范和标准,提出了设防烈度下码头岸坡变形的限值建议值,为我国的码头抗震设计提供参考。

Estimation of earthquake-induced permanent slope deformation based on response spectrum in code

Due to the damage of wharf structures caused by earthquake-induced permanent slope deformation, permanent slope deformation checking has been an important portion of seismic design for the wharves. Among various methods for calculating the permanent slope deformation, the Newmark rigid block displacement method has been widely utilized for its simplicity. The extensive empirical Newmark sliding block displacement equations, which are usually applied to regional-scale seismic landslide hazard analysis but not aimed to specific site, have been proposed based on natural strong-motion records in recent years. Targeting at the design response spectrum in the “Code for Seismic Design of Water Transport Engineering”, a set of artificial earthquake waves corresponding to different sites and peak ground accelerations are generated. Sliding block displacements under different yield accelerations and corresponding to various peak ground accelerations and sites are determined through double integration of portions exceeding yield acceleration over the acceleration time histories, and an equation for the sliding block displacement evaluation is put forward by regression analysis. In addition, based on the overseas codes and standards related to the wharf seismic design, the recommendation limitation under different precautionary intensities for the sliding displacement of the wharf slope is proposed, which can be taken as a reference for the wharf seismic design in China.