地震作用下含暗穴高边坡黄土路基稳定性分析

黄土暗穴是一种黄土高原地区发育的特殊的不良地质现象,已经成为我国黄土地区公路破坏的主要原因之一。黄土具有极高的动力易损性,在深入研究黄土暗穴发育特点的基础上,采用有限元法对其在地震力作用下的致塌机理进行了数值模拟,得出了无暗穴、拱形暗穴和三角形暗穴3种类型高边坡黄土路基在地震荷载作用下的动力响应规律,分析了暗穴对高边坡黄土路基的地震动放大效应。结果表明:黄土暗穴的存在具有地震动放大效应,在相同洞径和埋深条件下,拱形暗穴比三角形暗穴对高边坡黄土路基的水平加速度峰值的放大效果更为明显,尤其在坡肩和洞顶放大更为显著,说明黄土暗穴的存在对高边坡黄土路基存在不利影响,易在地震作用下发生坍塌破坏。

Stability analysis of high-slope loess subgradewith hidden holes under earthquake

As a kind of adverse geological phenomenon developed in the Loess Plateau,hidden holes in loess have become one of the main causes of highway damage in loess areas of China.On the basis of a deep study on the development characteristics of hidden holes in loess,the collapse mechanism under earthquake was simulated by the finite element method.The dynamic responses of three types of high-slope loess subgrade(subgrade without hidden hole,subgrade with arched hidden hole,and subgrade with triangle hidden hole)under seismic load were obtained,and the ground motion amplification effect of hidden holes on the high-slope loess subgrade was analyzed.The results showed that the hidden holes in loess has the effect of ground motion amplification.With the same hole diameter and buried depth,the amplification effect of arched hidden holes on the peak horizontal acceleration of high-slope loess subgrade is more obvious than that of triangular hidden holes,especially on the slope shoulder and hole roof.It is suggested that due to the existence of hidden holes in loess,the high-slope loess subgrade is prone to collapse and destroy under earthquake.