边坡地震动力响应规律及地震动参数影响研究

Dynamic response of slopes under earthquakes and influence of ground motion parameters

利用FLAC3D有限差分软件建立了一个边坡动力数值分析模型,用振动台模型试验对数值模拟效果进行了验证。在此基础上,分析了地震作用下边坡的动力响应规律,以及地震动参数对边坡动力响应的影响。结果表明,边坡对输入地震波存在垂直放大和临空面放大作用,边坡土体对输入地震波低频部分存在放大作用,对高频部分存在滤波作用。坡面加速度峰值放大系数随输入地震波振幅、频率的增加而减小,持时对加速度峰值响应的影响不大;坡体位移随振幅、持时的增加而显著增大,随频率的增大而减小。强震作用下剪应变增量最大区域的位置和形状表明,单一均质土层边坡的破坏模式仍是沿着某一弧形潜在滑动面失稳。研究结果有助于进一步揭示边坡在地震作用下的失稳机制。

A dynamic numerical simulation model of soil slopes was established with FLAC3D program, and the validity of simulation was validated with a shaking table model test. Based on this, the dynamic response laws and the influence of parameters of ground motion on the responses under earthquakes were analyzed. It was shown that the input seismic waves were affected by vertical and surface amplification of the slopes, and the effect amplified the input seismic waves with low frequency and filtered those with high frequency. It was reported that the coefficients of amplification of PGA along the slope surface decreased with the increase of amplitudes and frequencies of earthquakes, while these coefficients were less affected by the duration. It was also indicated that the maximum displacement of the slopes evidently increased with increase of amplitudes and duration of earthquakes while decreased with increase of frequencies. Furthermore, it was shown by the location and the shape of the maximum shear-strain increment region that the failure pattern of homogeneous soil slopes under earthquakes is instability along a potential sliding surface, similar to that under static condition. The results were helpful to further researches on the mechanism of slope instability under earthquakes.