重力坝砂土液化阻尼器减震技术

Seismic reduction with liquefied sand damper for gravity dams

探索一种新型砂土液化阻尼器的特性及对混凝土重力坝的减震效果．振动台试验表明液化砂土不存在惯性力和弹性力，仅具有与速度同步、反向的阻尼力；同时液化砂土具有高达500．1000kPas的动力黏度系数，可采用黏滞阻尼模型表示砂土液化阻尼器性能．应用有限元数值分析，混凝土重力坝采用砂土液化阻尼器坝顶将产生约0-3MPa的阻尼应力，坝顶位移峰值降幅达1／3；参数敏感性分析表明液化砂土波速为阻尼器减震的主要因素．砂土液化阻尼器不但构造简单，而且效果明显，是混凝土大坝等建筑物减震的新技术．

This paper presents a new seismic reduction approach to concrete gravity dams with the liquefied sand damper installed on the upper surface, similar to civil buildings with viscous dampers employed. The shaking table tests on the liquefied sand damper show the new damper is only of damping force, without spring and inertia forces existing. In particular, the liquefied sand damper is of the dynamic viscosity with range from 500 to 1000 kPa s. Hence, the linear viscos damping model is developed to the performance of the liquefied sand damper. With one 150-m-high gravity dam model using the new damper, the finite element simulation is carried out, with the seismic reduction of one third displacements obtained together with about 0.3 MPa damping shear stress existed. The parameter sensitivity analysis results in the seismic reduction of the liquefied sand damper linear to the wave velocity of liquefied sand. The proposed liquefied sand damper is of simple structure and of high damping efficiency, being suitable for gravity dams excited by potential strong earthquake.