可液化土中格栅加筋土挡墙地震变形特性大型振动台试验

Large-scale Shaking Table Tests on Seismic Deformation of Geo-grid Reinforced Soil Retaining Walls in Liquefiable Soils

为了研究地震中饱和回填砂里土工格栅加筋土刚性挡墙的变形特性以及土工格栅在加筋结构里的抗震作用,建立了土工格栅加筋和无格栅加筋的土墙结构模型,并展开振动台试验研究。通过量纲分析理论的Froude常数推定加筋土墙体结构和未加筋墙体结构的几何相似比以及其他变量的相似设计,采用地震侧胀仪测试模型场地剪切波速;考虑地震动强度影响,测试了2个模型的墙体侧向水平变形反应特征、回填土表面沉降和孔隙水压力特性,并得到格栅加筋墙体地震残余变形与超静孔隙水压力比的关系。研究结果表明:加筋墙体地震侧向变形和加筋区回填土表面沉降因土工格栅的存在而显著降低,墙体变形呈现类似倾斜并带有屈曲外鼓的变形模式;土工格栅的存在消减了加筋区孔隙水压力的增长。

In order to study seismic deformation characteristics of geo-grid reinforced soil retaining wall and seismic effect of geo-grid in reinforced structure for saturated backfill sands, two test models for geo-grid reinforced soil retaining walls and retaining walls without geo-grid were constructed for large-scale shaking table test. The geometric similarity ratios of two models were deduced by the constant of Froude in dimensional analysis theory and the similarity designs of other variables were deduced from the geometric similarity ratios. A seismic dilatometer was used to test the shear wave velocity of model ground. With seismic intensity considered, seismic lateral horizontal deformations of walls, seismic settlements of backfill soils and pore water pressures of backfill soils in two models were tested. Finally, the relationship was derived between the seismic residual deformations of reinforced walls and excess pore water pressure ratios of backfill soils.The results show that the lateral deformations of reinforced walls and seismic settlements of backfill soils in the reinforced zone decrease significantly due to geo-grid. The lateral deformations of reinforced walls are inclining outwards and in some positions are swelling outwards. Geo-grid slows down the increase of pore water pressure in the reinforced zone.