岩土边坡地脉动特性及地震稳定性研究

发布时间：2018-05-10 22:18

本文选题：天水市 + 地脉动　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：根据在天水市西部黄土地区9个边坡上测试的68个地脉动数据,运用频谱分析法得出边坡的卓越周期;利用7个钻孔编录和剪切波速测试数据,按场地土层一维动力响应理论分析结果计算边坡土体自振周期,两种方法所得结果比较一致。为天水市黄土地区大型滑坡和自然斜坡的动力特性分析提供了依据。考虑场地周边不同方位的潜源地震带对边坡地震稳定性的影响,在FLAC3D软件中输入不同方向的简谐P波、SH波和SV波的地震动应力时程,运用“荷载增强法”对郑家磨边坡进行了地震稳定性分析,总结得出了如下认识和成果:(1)天水地区典型边坡地脉动卓越周期:覆盖层厚度为20~40m的滑坡为0.31s;覆盖层厚5~10m的自然边坡为0.26s。(2)郑家磨边坡对以不同角度入射的简谐P波的地震动响应的塑性区分布特点不同。总体来看垂直入射引起的拉张破坏区密集,且集中于局部陡倾(曲率变化大)的边坡表面,剪切破坏区多位于边坡后缘;斜入射引起的拉张破坏区零散分布于坡面,但剪切破坏区深度大,位于坡体后缘且向后壁延伸。(3)郑家磨边坡对不同类型的简谐波斜入射地震动响应的塑性区贯通特点不同。P波引起的塑性区有沿着Y轴反向贯通的趋势;SH波引起的塑性区有沿着Z轴正向贯通的趋势,且深度为三种震相中最大;SV波引起的塑性区有沿着Y轴正向贯通的趋势,深度则为三种震相中最小。(4)郑家磨边坡对不同类型的简谐波斜入射的边坡稳定性系数不同。总体来说各个方位角入射时,SH波的稳定性系数最大;而SV波得出的稳定性系数最小;P波介于两者之间。(5)相对于不同类型的简谐波斜入射,边坡稳定性最小方向相近。总体来看,地震波以方位角22.5°(西偏南)入射时边坡地震稳定性最差,此方向与天水地区活动断裂及潜在震源区的走向接近,且该方向的边坡边界:侧壁较高陡,曲率变化大。(6)激振频率对边坡临界地震峰值加速度的影响很大,当激振频率是卓越频率时,边坡的临界地震峰值加速度最小,边坡地震稳定性最差。
[Abstract]:According to 68 ground pulsation data measured on 9 slopes in western loess area of Tianshui City, the remarkable period of slope was obtained by using spectrum analysis method, and the data of 7 borehole cataloguing and shear wave velocity test were used. The natural vibration period of slope soil is calculated according to the theoretical analysis of one-dimensional dynamic response of the site soil layer. The results obtained by the two methods are in good agreement with each other. It provides a basis for dynamic analysis of large landslide and natural slope in loess area of Tianshui City. Considering the influence of the potential source seismic zone around the site on the slope seismic stability, the seismic stress history of the harmonic P wave SH wave and SV wave in different directions is input into the FLAC3D software. The seismic stability analysis of Zhengjiamo slope is carried out by means of "load enhancement method". The results are summarized as follows: the remarkable period of ground pulsation of typical slope in Tianshui area is 0.31 s for the landslide with cover thickness of 20 ~ 40 m and 0.26 s. 2 for the natural slope with a thickness of 5 ~ 10 m). The plastic zone distribution of the seismic response of the wave is different. In general, the tensile failure zone caused by vertical incidence is dense and concentrated on the surface of the slope with a local steep dip (with a large change in curvature), and the shear failure zone is mostly located at the back edge of the slope, and the tensile failure zone caused by oblique incidence is scattered on the slope. But the shear failure zone is deep, The plastic zone of Zhengjiamo slope in response to different types of simple harmonic oblique incident ground motion the plastic zone caused by .P wave has the tendency of reverse transfixion along Y axis and SH wave is caused by the plastic zone which is located at the back edge of the slope and extends to the back wall of the slope.) the plastic zone of the Zhengjiamo slope responds to different types of simple harmonic oblique incidence ground motion. The plastic zone has a trend of forward transfixion along the Z axis. And the plastic zone caused by the maximum SV wave in the three seismic phases has the trend of forward transfixion along the Y axis, while the depth is the smallest in the three phases. The slope stability coefficient of Zhengjiamo slope for different types of harmonic oblique incidence is different. As a whole, the stability coefficient of SH wave is the largest when the azimuth angle is incident, while the minimum P wave of SV wave is between them. In general, the seismic stability of the slope is the worst when the seismic wave is incident with the azimuth angle of 22.5 掳(south-west), which is close to the active fault in Tianshui area and the strike of the potential focal area, and the slope boundary in this direction is high and steep. When the exciting frequency is excellent, the critical peak acceleration of slope is the least, and the slope seismic stability is the worst.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.9;TU435

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