基于振动台试验的纯黄土边坡动力响应研究

黄土地区地震岩土灾害严重,本文以兰州新区一纯黄土边坡为原型,开展了大型振动台模型试验,研究纯黄土边坡在地震荷载作用下的动力响应规律与破坏机制。结果表明:与其他岩性或土性的边坡一样,纯黄土边坡表层加速度放大效应明显,在坡肩附近达到最大,呈现出高程效应即随高程的增加放大效应增强,同时放大效应也会随地震烈度的增加而增强,当烈度达到600 gal时,坡肩处放大系数最大为2.06;边坡表层土压力远小于与其同一高程的内部土压力,表层变化规律基本一致且随地震动的增加数值相差不大,在临空面上,坡脚附近土压力为最大,其值在0.7~0.75 kPa;随地震烈度的增加,边坡表面裂纹逐步由细小短裂缝演变为横向贯穿的深裂缝,在坡肩附近尤为显著,试验中,最大沉降约10 cm,坡肩最大水平位移为5~8 cm,模型边坡最终发生拉裂滑移式破坏。该研究结果可为纯黄土边坡在地震荷载作用下的稳定性研究提供一定参考。

Dynamic Response of Loess Slopes Based onthe Shake Table Test

In the loess region, the geotechnical disasters caused by the earthquake are serious. Taking a loess slope in the new Lanzhou area as a prototype, we conducted a large-scale oscillating table model test to study the dynamic response law and the loess slope failure mechanism under the earthquake load. The results showed that the acceleration amplification effect on the loess slope surface is obvious and reaches its maximum value on the slope shoulder. Meanwhile, the amplification effect increases with increasing seismic intensity, when the intensity reaches 600 gal, the maximum amplification coefficient on the slope shoulder is 2.06. The result also showed that ground pressure on the slope surface is less than the pressure on the slope body at the same elevation. The maximum value appeared on the slope of the free face and the value varies between 0.7-0.75 kPa. As the seismic intensity increases, the slope''s superficial fissure gradually changes from a small short to a deep fissure, especially near the shoulder of the slope. In the test, the maximum settlement is about 10 cm and the maximum horizontal displacement of the slope shoulder is about 5-8 cm. The final failure mode of the model slope is traction break-slip. The research results may provide some reference for studying the stability of the loess slope under earthquake loads.