基于振动台试验的黄土塬边斜坡变形失稳模式研究

Deformation and Failure Mode of Loess Tableland Slopes Based on Shaking Table Test

以甘肃省平凉市的典型黄土塬斜坡为原型,开展含裂隙黄土塬边斜坡与不含裂隙黄土塬边斜坡的振动台对比模型试验,研究不同强度地震作用下两种黄土斜坡的变形失稳特征。结果表明:两种不同结构的斜坡在不同强度地震作用下的破坏特征显著不同,裂隙的存在降低了含裂隙斜坡的抗震稳定性。随着输入地震波幅值的增加,含裂隙斜坡的变形破坏过程为:坡顶裂隙处先后发生裂隙前缘崩塌、坡面溜土、临空面方向大位移、坡面中部和坡脚鼓胀、剪切滑移、发生多级滑动,同时坡体后缘产生新的拉张裂隙;无裂隙斜坡的破坏过程为:坡顶形成拉张裂缝、坡面溜土、坡脚鼓胀、发生单级滑动。两种结构边坡的变形破裂包括倾倒—拉裂与剪切—滑移两种模式,斜坡的变形演化是两种模式相互作用的结果。

Taking a typical loess tableland slope in Pingliang city,Gansu Province,as the prototype,a large-scale shaking table test was performed on the loess tableland slope with and without cracks to study the deformation and failure characteristics of the two slopes under different earthquakes.The results showed that the failure characteristics of the two slopes with different structures were significantly different under earthquakes of different intensities.The existence of cracks reduced the seismic stability of the cracked slope.With the increase in the input seismic amplitude,the deformation and failure process of the slope with and without cracks were obtained.The deformation and fracture of slopes with two structures included two patterns:toppling-tension or shear-slip.The deformation evolution of slopes was the result of the interaction of the two models.