State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, China.
College of Environment and Civil Engineering, Chengdu University of Technology, Chengdu, China.
PLoS One. 2021 Apr 21;16(4):e0250418. doi: 10.1371/journal.pone.0250418. eCollection 2021.
The weak interlayer in a rock slope often plays a significant role in seismic rockslides; however, the effect of weak interlayer on the seismic slope response and damage process is still not fully understood. This study presents a series of shaking test tests on two model slopes containing a horizontal weak interlayer with different thicknesses. A recorded Wenchuan earthquake ground motion was scaled to excite the slopes. Measurements from accelerometers embedded at different elevations of slope surface and slope interior were analyzed and compared. The effect of the weak interlayer thickness on the seismic response was highlighted by a comparative analysis of the two slopes in terms of topographic amplification, peak accelerations, and deformation characteristics as the input amplitude increased. It was found that the structure deterioration and nonlinear response of the slopes were manifested as a time lag of the horizontal accelerations in the upper slope relative to the lower slope and a reduction of resonant frequency and Fourier spectral ratio. Test results show that under horizontal acceleration, both slopes exhibited significant topographic amplification in the upper half, and the difference in amplification between slope face and slope interior was more pronounced in Slope B (with a thin weak interlayer) than in Slope A (with a thick weak interlayer). A four-phased dynamic response process of both slopes was observed. Similar deformation characteristics including development of strong response zone and macro-cracks, vertical settlement, horizontal extrusion and collapse in the upper half were observed in both slopes as the input amplitude increased; however, the deformations were more severe in Slope B than in Slope A, suggesting an energy isolation effect of the thick interlayer in Slope A.
岩质边坡中的软弱夹层在地震滑坡中常常起着重要的作用；然而，软弱夹层对地震边坡响应和破坏过程的影响仍未被充分理解。本研究对两个含有不同厚度水平软弱夹层的模型边坡进行了一系列振动台试验。采用汶川地震记录的地震动对边坡进行了模拟。分析和比较了不同边坡表面和内部位置处加速度计的测量结果。通过对比分析两个边坡的地形放大、峰值加速度和变形特征，突出了软弱夹层厚度对地震响应的影响。研究结果表明，随着输入振幅的增加，边坡结构的劣化和非线性响应表现为上边坡水平加速度相对于下边坡的时间滞后，以及共振频率和傅里叶谱比的降低。试验结果表明，在水平加速度作用下，两个边坡在上半部分都表现出显著的地形放大，而在软弱夹层较薄的边坡 B 中，边坡表面和内部之间的放大差异比软弱夹层较厚的边坡 A 更为明显。观察到两个边坡都经历了四个阶段的动力响应过程。随着输入振幅的增加，两个边坡都表现出类似的变形特征，包括上半部分强响应区和宏观裂缝的发展、垂直沉降、水平挤压和崩塌；然而，边坡 B 的变形比边坡 A 更为严重，这表明边坡 A 中厚夹层具有能量隔离效应。
