基于振动台试验的含软弱夹层堆积体边坡动力响应规律与失稳破坏现象研究

针对川藏铁路沿线典型潜在滑坡灾害点,设计完成了几何相似比为1:10的含软弱夹层堆积体高陡边坡振动台试验,从滑塌现象、动力特性及成因机制等方面开展了系统研究,得出以下结论：边坡滑塌是一个均衡渐进的过程,在地震初期,在重力和地震力耦合作用下,滑体表面出现土体剥落；随着地震动持续,滑体顶部开裂,滑体表面裂缝增多并向前缘锁固段发展；最终,锁固段发生渐进性破坏,滑动面贯通,滑体从前缘剪出口滑出形成滑坡；以坡脚处的加速度峰值为基准,在不同烈度汶川卧龙地震波作用下,堆积体高陡边坡临空面方向、竖直方向上PGA沿着高程均有不同程度的放大,且边坡临空面向加速度放大性大于竖直方向。不论是边坡临空面方向还是竖直方向,随着输入地震动峰值的增大,加速度高程放大系数逐渐增大,在PGA=0.4g时达到峰值；滑床、滑体间运动的不一致性是诱发滑坡的一项主控影响因素,在堆积体滑塌前,堆积体内临空面的加速度峰值及其傅立叶幅值大于滑床,且两者的卓越频带基本一致,略有差别；当堆积体开始滑塌时,堆积体内临空面的加速度峰值及其傅立叶幅值小于滑床,且卓越频带逐渐向低频转移,而滑床内的加速度傅立叶谱的主频和幅值基本不变。

Research on Dynamic Response and Instability Failure Phenomenon of Deposit Slope with Weak Interlayer Based on Shaking Table Test

Aiming at the typical potential landslide disaster points along the Sichuan-Tibet Railway, the design has completed a shaking table test of a high-steep deposit slope with weak interlayer with a geometric similarity ratio of 1:10. The conclusion has been drawn as follows: Slope landslide is a balanced and gradual process. At the beginning of the earthquake, under the influence of gravity and seismic force, the soil on the surface of slope began to peel off; as the ground motion continued, the top of the sliding body cracked, The cracks on the surface of the sliding body increase and develop at the front edge locking section; finally, the locking section is damaged, the sliding surface is penetrated, and the sliding body slides out from the cutting outlet of the leading edge to form a landslide. Based on the PGA of the foot of slope, under the action of WC seismic waves of different intensities, The PGA along the elevation of the high-steep deposit slope has different degrees of magnification in the direction of the free surface and the vertical direction, the acceleration amplification effect on the free surface direction of slope is bigger than the acceleration amplification effect on the vertical direction. Regardless of whether it is the surface direction or the vertical direction of the slope, with the increase of the input ground motion peak value, the acceleration elevation amplification factor gradually increases, and reaches the peak value at PGA=0.4g. The inconsistency of the movement between the sliding bed and the sliding body is one of the main controlling factors that induce landslides. Before the accumulation body collapses, the acceleration peak value and the Fourier amplitude of the surface of the deposit slope are greater than the sliding bed, and the excellent frequency bands of the two are basically the same. When the accumulation body begins to collapse, the acceleration peak value and the Fourier amplitude of the surface of the accumulation body are smaller than the slider bed, and the superior frequency band gradually shifts to low frequency, while the main frequency and amplitude of the Fourier spectrum of acceleration in the slider bed are basically unchanged.