离石黄土地层崩塌隐患体的地震波速特征

CHARACTERISTICS OF SEISMIC WAVE VELOCITY OF POTENTIAL SLOPE FAILURE IN LISHI LOESS STRATA

崩塌是黄土高原地区最常见、致灾最为严重的地质灾害之一。本文通过野外钻探,采用原位地震波测试的方法,详细分析了离石黄土崩塌隐患体内部的波速结构特征。结果发现,在竖直方向上,地震波速整体随深度增加而增大;水平方向上,地震波速自边坡坡面向坡体内部逐渐增大。结合数值模拟,发现崩塌隐患体由于受到卸荷回弹作用的影响,产生了指向坡外的形变。形变增量的大小与距离边坡坡面的远近有关,距离坡面越近形变增量越大,致使对应土体的密实度减小。密实度的减小是隐患体内部波速存在差异的重要原因。研究表明,利用地震波速的变化规律可以宏观反映崩塌隐患体内部结构特征,进而指导黄土崩塌地质灾害的防治研究。

Collapse is one of the most common and serious geological disasters in the Loess Plateau of China.In this paper,the seismic wave velocity characteristics of the potential slope failure internal structure of Lishi loess are analysed in detail using the in-situ seismic wave testing through field drilling test.The results show that the seismic wave velocity in the vertical direction increases with the depth,while the seismic wave velocity in the horizontal direction gradually increases from slope surface to interior of the slope.Numerical simulation results indicate that the potential slope failure generates outward deformation due to the unloading rebound.The deformation increment is related to distance to the slope surface,the closer the distance,the greater the deformation increment.The decrease of density is an important reason for the difference of wave velocity in the potential failure.The study shows that the variation pattern of seismic wave velocity can reflect the internal structure characteristics of the potential slope failure,and thus can be a method in research on prevention and control of loess collapses.