成层液化场地振动台震前震后场地土性质变化试验研究

    Experimental Study on Changes in Site Soil Properties Before and After Seismic Excitation in Stratified Liquefaction Sites on Vibration Tables

    • 摘要: 砂土液化是地震工程中导致场地失效的主要灾害之一。目前研究多集中于液化现象本身及上部结构响应,而对液化发生后场地土体自身物理力学性质的系统性变化研究相对不足。本研究设计并完成了一个成层砂土-黏土模型场地的振动台试验,通过对比分析震前与震后场地的钎探锤击数(钎探试验)、剪切波速(波速试验)以及地表沉降量,结合震后成层土含水率、密度、抗剪强度参数(直剪试验)等一系列关键指标,系统地揭示了液化过程对场地土体性质的改造作用。试验结果表明,液化后饱和砂层发生显著的排水再固结,导致钎探锤击数和剪切波速大幅提升,同时引发可观的地表沉降;黏土层性质变化相对微小。本研究为理解液化后场地性能演变及震后地基再利用提供了重要的试验依据。

       

      Abstract: Sand liquefaction is one of the primary hazards causing site failure in earthquake engineering. Current research predominantly focuses on the liquefaction phenomenon itself and the response of superstructures, while systematic investigations into the physical and mechanical property changes of the site soil following liquefaction remain relatively scarce. This study designed and conducted a shake table test on a layered sand-clay model site. By comparing and analyzing pre- and post-shake values of hammer blows (pen test), shear wave velocity (wave velocity test), and surface settlement before and after the earthquake. By integrating post-earthquake key indicators such as moisture content, density, and shear strength parameters (direct shear test) of the layered soil, this study systematically reveals the transformative effects of liquefaction on site soil properties. Results indicate that saturated sand layers undergo significant drainage and reconsolidation post-liquefaction, substantially increasing hammer blows and shear wave velocity while inducing considerable surface settlement. The underlying clay layer exhibits relatively minor property changes, though its moisture content slightly increases due to drainage effects from the upper layer. This study provides crucial experimental evidence for understanding post-liquefaction site performance evolution and post-earthquake foundation reuse.

       

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