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地震荷载作用下堆积层斜坡稳定性分析
Alternative TitleStability Analysis of Accumulative Slope during Earthquake
Language中文
郭亚永
Thesis Advisor崔鹏
2016
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name硕士
Degree Discipline岩土工程
Keyword堆积层斜坡 动力响应特征 失稳破坏模式 安全系数 永久位移
Other Abstract

堆积层斜坡在中国西南山区广泛分布,其在地震荷载作用下的稳定性问题突出。论文以堆积层斜坡为研究对象,对其进一步分类,总结了斜坡动力稳定性的影响因素,设计了相应的数值模拟试验,分析研究了堆积层斜坡的动力响应特征和失稳破坏模式。另外,从理论和实例对比两方面,分析了各斜坡稳定性评价方法的优缺点及适用范围,并对刚塑性滑块分析法进行了改进。最后利用相适用的稳定性评价方法对鲁甸地震诱发的甘家寨滑坡进行了分析。通过上述研究,主要得到以下结论:(1)堆积层斜坡可分为浅层堆积层斜坡、无软弱层中层堆积层斜坡、夹软弱层中层堆积层斜坡、无软弱层深厚层堆积层斜坡和夹软弱层深厚层堆积层斜坡。其稳定性主要受输入坡体的地震波特征(包括峰值加速度、频率和持时)、坡形(坡高、坡度)和岩土体力学参数(E、c和φ)三大方面的影响。(2)堆积层斜坡对地震加速度的响应规律主要包括:坡体对输入地震波有明显的垂直放大作用和临空面放大作用;在基覆界面及堆积层内加速度放大效应明显增强;软弱层对地震波有一定的隔震作用;坡肩对地震加速度的放大作用最强,且堆积层越厚,放大作用先增强后有所减弱;输入地震波峰值加速度越大,基覆面、坡面和坡肩处加速度响应越弱;频率和持时对加速度响应特征影响不大;坡体越高,坡顶和坡肩处加速度响应越弱,坡面处变化不大;坡体越陡,基覆面、坡面和坡肩处加速度响应越强;堆积层的弹性模量、黏聚力和内摩擦角越大,其对加速度的放大作用越强。另外,堆积层斜坡的失稳破坏模式主要受堆积层斜坡类型、峰值加速度、坡度、弹性模量和强度参数影响,这些方面的组合可诱发堆积层斜坡失稳后形成四类滑坡类型:基岩-堆积层接触面滑坡、基岩-堆积层组合型滑坡、堆积层内直线形滑坡和堆积层内圆弧形滑坡。(3)拟静力极限平衡分析法中摩根斯坦-普赖斯法和斯宾森法计算更加精确,然而拟静力系数的选择对计算结果影响较大。有限元时程曲线法中的最小平均安全系数法可以较为合理的判断斜坡的安全性。另外,当场地竖直加速度较大,且动孔压增长明显时,两者对永久位移的贡献明显,不可以忽略,此时应该选用考虑竖直加速度和动孔压的改进的刚塑性滑块分析法。在永久位移分析法的选择上,当Ts/Tm比值小于0.1时,即浅层且土质坚硬的堆积层斜坡,宜采用刚塑性滑块分析法;当Ts/Tm比值大于0.1时,宜采用耦合分析法。(4) 甘家寨滑坡属于无软弱层深厚层堆积层斜坡失稳滑动后形成的基岩-堆积层滑坡,在鲁甸地震作用下其安全系数在0.94-0.99之间,永久位移为20.6cm,均可说明甘家寨已失稳滑动。

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Accumulative slope is widely distributed in the southwest of china, and its stability under seismic load is a prominent issue. This thesis takes accumulative slope as the research object, classifies it further, summarizes the factors which affect the stability of slope, designs the corresponding numerical simulation, and analyses the dynamic response characteristics and instability mechanism of accumulative slope. In addition, from the perspective of theory and practical case, this thesis analyzes the merits and demerits of each method for assessing the stability of slope under seismic load, and improves the Newmark’s method. Finally this thesis assesses the stability of Ganjiazhai landslide during the Ludian earthquake using the applicable methods. Through the above research, the main conclusions are as follows:(1) The accumulative slope could be divided into five types: shallow accumulative slope, middle accumulative slope without soft layer, middle accumulative slope with soft layer, deep accumulative slope without soft layer, deep accumulative slope with soft layer. The stability of slope is mainly affected by characteristics of seismic wave(peak acceleration, frequency and duration), slope form(height and gradient), and mechanical parameters(E, c and φ).(2) Dynamic response laws of accumulative slope include: the slope has vertical and free surface amplification effect on the input seismic waves; acceleration magnified effect is strengthened on the rock-soil contact interface and in the accumulation; the weak layer has shock isolation effect; the slope shoulder has the strongest acceleration magnified effect, and the effect is enhanced, then weakened with the accumulation layer thicker; the greater the peak acceleration of the input seismic wave is, the weaker the acceleration magnified effect of rock-soil contact interface, slope surface and slope shoulder is; the frequency and duration have little effect on dynamic response characteristics; the slope is higher, and the acceleration magnified effect is weaker on the slope crest and shoulder; the steeper the slope is, the acceleration magnified effect of rock-soil contact interface, slope surface and shoulder is stronger; the greater the E, c and φ of the accumulation layer is, the stronger the acceleration magnified effect is. Moreover, the instability mechanism of accumulative slope is mainly effected by slope type, peak acceleration, slope angle, E, c and φ. Various combinations of these aspects can induce four types of landslide: rock-soil interface landslide, rock-soil landslide, homogeneous soil landslide with linear slip surface and homogenous soil landslide with arc slip surface.(3) Morgenstern-Price and Spencer method of pseudo-static analysis is more precise, but the choice of the coefficient of pseudo-static is more important. The minimum mean safety factor of time history analysis using finite element can be a reasonable index to evaluate the safety of slope. When the vertical acceleration is great and the dynamic pore water pressure increase apparently, the contribution of both to permanent displacement could not be ignored. At this time, the improved Newmark’s method which considers vertical acceleration and dynamic pore water pressure should be selected. In the selection of the permanent displacement, Newmark’s method should be selected when Ts/Tm is less than 0.1, that is for stiffer and thinner accumulative slope. Coupled analysis should be selected when Ts/Tm is more than 0.1.(4) Ganjiazhai landslide is belonged to rock-soil interface landslide from deep accumulative slope without soft layer. Its safety factor during Ludian earthquake is between 0.94-0.99, permanent displacement is 20.6cm, both of index can explain that Ganjiazhai was already unstable during earthquake. 

Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/18877
Collection山地灾害与地表过程重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
郭亚永. 地震荷载作用下堆积层斜坡稳定性分析[D]. 北京. 中国科学院大学,2016.
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