岩石场地重力式挡土墙地震土压力振动台实验研究

Shaking Table Model Experimental Study on Seismic Soil Pressure of GRW on Rock Site

结合汶川震区调查资料,利用大型振动台模型试验,分析了碎石土填料的岩石场地重力式挡土墙的地震土压力及其分布规律,并以此对我国现行铁路、公路抗震规范做合理性讨论和细化。研究发现,地震作用下,挡土墙的动土压力沿墙高呈单峰曲线状分布,且60%～80%集中作用于挡墙中部;随着地震峰值加速度的增加,地震土压力分布逐渐偏离现行振震设计规范所认为的三角形线性状,而呈现非线性状;合力作用点高于1/3墙高,0.4g地震加速度作用下,接近0.4倍墙高,对岩石场地下粗粒径墙背填料的地震土压力作用点高度,建议取0.35倍墙高。对比计算表明,现行规范能基本满足工程抗震设计需要,但建议对柔性挡土墙的抗震设计作出必要规定。

After the occurrence of a destructive earthquake,according to building and structure damage characteristics,it is important and imperative to revise the current seismic design codes.Combining with the seismic damage investigation in Wenchuan earthquake,this paper analyzes the seismic earth pressure of crushed gravel filled gravity retaining wall（GRW）and distribution of earth pressure by using large-scale shaking table model test.Based on the above analysis,reasonable discussion and refinement are made on current seismic design codes of railway and highway.The following conclusions are drawn.First the earth pressure on the GRW shows a single peak curve distribution along the wall and 60%～80%acting on the central.Second,with the increase of peak ground acceleration,the seismic earth pressure distribution gradually deviates from the triangular linear distribution.The acting point of resultant force is higher than 1/3 of the wall high,in fact,nearly 0.4 times the wall high under the action of seismic acceleration.On rock site with coarse wall back fill,it is suggested that the acting height of seismic earth pressure takes 0.35 times the wall height.Finally,comparative calculations show that current seismic design specifications can basically meet the project requirements,but it is suggested to make the necessary provisions about seismic design of flexible retaining walls.