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1.
Seismically induced landslide displacements: a predictive model 总被引：27，自引：0，他引：27
Newmark's model for predicting earthquake-induced landslide displacements provides a simple way to predict the coseismic displacements affecting a sliding mass subject to earthquake loading. In this model, seismic slope stability is measured in terms of critical acceleration, which depends on the mechanical soil properties, pore-pressure distribution, and slope geometry. The triggering seismic forces are investigated in terms of energy radiation from the source, propagation, and site effects, based on 190 accelerometric recordings from 17 Italian earthquakes with magnitudes between 4.5 and 6.8. The method is based on the calibration of relations having the general form of an attenuation law that relates the energy of the seismic forces to the dynamic shear resistances of the sliding mass to propagate the expected landslide displacements as an inverse function of the distance from the fault rupture; the amount of displacement computed through these relations provides a criterion to predict the occurrence of slope failures. Finally, maps showing, in a deterministic and a probabilistic way, the potential of seismically induced landslide displacements are displayed as a tool to provide seismic landslide scenarios and earthquake-induced landslide hazard maps, respectively. 相似文献
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Analysis on mechanism of landslides under ground shaking: a typical landslide in the Wenchuan earthquake 总被引：1，自引：1，他引：0
Yang Changwei Liu Xinmin Zhang Jianjing Chen Zhiwei Shi Cong Gao Hongbo 《Environmental Earth Sciences》2014,72(9):3457-3466
A high steep rock hill with two-side slopes near National Road 213 is used as a prototype in this paper. The full process from initial deformation to sliding of the slope during ground shaking is simulated by a new discrete element method—continuum-based discrete element method. Then, the seismic responses of a high steep rock hill with two-side slopes are researched from the base of time, frequency and joint time–frequency domain using Hilbert–Huang transform and Fourier Transform. The findings are: first, the stress concentration phenomenon occurs at the top of the sliding mass, and then some tension and shear failure points appear, which expand from the top toward the toe of the sliding mass along the structural plane. At the same time, the number of tension failure points gradually increases. Then the toe of the sliding mass fails, and shears out from its toe which results in the landslide. If the material parameters are under the same conditions, the landslide in the middle of the slope occurs before that at the foot of slope, and the starting time of landslide and the arrival time of the peak ground acceleration are synchronous or the former slightly lags behind the latter. The difference of distribution and dissipation of earthquake energy in the sliding body and sliding bed is the major influence factor to induce the landslide. When the accelerations are small, the instantaneous frequency of accelerations between sliding bed and sliding body is generally consistent, the energy transmittance coefficients of the sliding structural plane and the controlled frequency band of the energy all range in a limitation; with the increase of the seismic intensity, the instantaneous frequency and the energy transmittance coefficients gradually decrease, and then they are steady within the lower limitation. At the same time, the controlled frequency band also shifts gradually from high frequency band to the lower one. Based on the input seismic wave, the peak acceleration amplifies as the increase of elevation, regardless of the monitoring points on the steep slope, gentle slope side or inside of the slope. Generally speaking, amplification of the vertical peak acceleration is stronger than that of the horizontal peak acceleration, and amplification of the peak acceleration on a steep slope is stronger than that on a gentle slope, and that of inside of the slope is the weakest amplification. 相似文献
4.
考虑强度退化效应的堤坝抗震稳定性评价方法 总被引：2，自引：2，他引：2
考虑土的动强度随振动孔隙压力上升的衰减效应,将拟静力极限平衡分析和滑动体位移分析相结合,提出了堤坝抗震稳定性评价方法.首先,基于土工动力有限元分析,确定坝坡潜在滑动土体的平均加速度时程,进而,基于拟静力概念,采用极限平衡分析,确定坝坡的安全系数随时间的变化历程,其中当安全系数瞬时小于1时,表明坝坡在地震中处于瞬时超载状态,采用Newmark刚体滑块模型估算瞬时超载所产生的滑动位移,将各个超载阶段的滑动位移叠加,求得设计地震动作用下堤坝边坡的累积滑移量,根据这种方法所进行的数值计算与分析表明,考虑强度循环退化效应后所得到的坝坡滑移量更为合理. 相似文献
5.
Different models were developed for evaluating the probabilistic three-dimensional (3-D) stability analysis of earth slopes and embankments under earthquake loading. The 3-D slope stability model assumed is that of a simple cylindrical failure surface. The probabilistic models evaluate the probability of failure under seismic loading considering the randomness of earthquake occurrence, and earthquake induced acceleration and uncertainties stemming from the discrepancies between laboratory-measured and in-situ values of shear strength parameters. The models also takes into consideration the spatial variabilities and correlations of soil properties. The probabilistic analysis and design approach is capable of obtaining the 2-D and 3-D static and dynamic safety factors, the probability of slope failure, the earthquake induced acceleration coefficient, the yield acceleration coefficient, the earthquake induced displacement, and the probability of allowable displacement exceedance taking into account the local site effect. The approach is applied to a well known landslide case: Congress Street Landslide in Chicago. A sensitivity analysis was conducted on the different parameters involved in the models by applying those models to the Congress Street landslide considering different levels of seismic hazard. Also, a sensitivity analysis was carried out to study the sensitivity of computed results to input parameters of undrained shear strength, and corrective factors. A comparison was made between the different models of failure. The parametric study revealed that the hypocentral distance and earthquake magnitude have major influence on the earthquake induced displacement, probability of failure and dynamic 2-D and 3-D safety factors. 相似文献
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Vertical acceleration effect on landsides triggered by the Wenchuan earthquake,China 总被引：3，自引：0，他引：3
Yueping Yin 《Environmental Earth Sciences》2014,71(11):4703-4714
The 2008 Wenchuan earthquake with Ms8.0 triggered extensive throwing-pattern landslides in the area within or near the seismic faults. The resultant landslides from this earthquake brought to the fore the effect of vertical earthquake acceleration on landslide occurrence. The pseudostatic analysis and the dynamic response on landslide stability due to the Wenchuan earthquake are studied with the Chengxi (West Town) catastrophic landslide used as a case study. The results show that the epicenter distance is an important factor which affects the vertical acceleration and thus the stability of landslide. Also, the vertical acceleration was found to have a significant impact on the FOS of landslide if the earthquake magnitude is quite large. Within the seismic fault, the amplitude effect of vertical acceleration is very dominant with the FOS of landslide, for vertical acceleration ranging from positive to negative, having a variation of 25 %. The variation of FOS of landslide for vertical acceleration ranging from positive to negative are 15 and 5 % for landslides near seismic fault and outside seismic fault, respectively. For landslide with a slope angle <45°, the FOS of landslide with both horizontal and vertical accelerations is significantly greater than the one without vertical acceleration. Further, the results computed from both the pseudostatic method and dynamic analysis reveal that the FOS during the earthquake varied significantly whether vertical acceleration is considered or not. The results from this study explain why lots of throwing-pattern catastrophic landslides occurred within 10 km of the seismic fault in the Wenchuan earthquake. 相似文献
7.
基于简化 Newmark位移模型的区域地震滑坡危险性快速评估以汶川MS 8.0级地震为例 总被引：1，自引：0，他引：1
以汶川MS8.0级地震重灾区的11县市为例,初步提出了基于简化Newmark位移模型的地震滑坡危险性应急快速评估方法。利用汶川地震即时地震动参数、工程地质岩性经验分组及地形坡度数据,借助ArcGIS空间数据建模工具编制了地震滑坡危险性快速评估流程模块。计算了区域浅表层饱和岩土体斜坡的静态安全系数Fs、临界加速度ac,并借此分析了地震滑坡易发性。利用经验式获得了汶川地震Arias强度和区域滑坡位移DN分布,实现了汶川地震重灾区地震滑坡危险性的快速评估,为应急救灾决策提供了参考。通过对比评估结果和震后滑坡调查成果,可知数十处灾难性滑坡绝大部分位于-高危险区的龙门山主中央断裂带两侧约20km地带中,显示了评估方法的可靠性; 同时,分析指出了空间数据精度及更新不足导致局部评估结果欠佳的局限性,并提出了改进建议。 相似文献
8.
Influence of seismic acceleration on landslide susceptibility maps: a case study from NE Turkey (the Kelkit Valley) 总被引：2，自引：0，他引：2
Particularly in the last decade, landslide susceptibility and hazard maps have been used for urban planning and site selection of infrastructures. Most of the procedures for preparing of landslide susceptibility maps need high-quality landslide inventory map. Although the rainfall and seismic activities are accepted as triggering factor for landslides, designation of the triggering factor for each landslide in the inventory is almost impossible when well-documented records are unavailable. Therefore, during preparation of landslide susceptibility map, whole landslide records in the inventory map are used together without classifying based on the triggering factors. Although seismic activity is accepted as a triggering factor, possible effect of the use of seismic activity on production of landslide susceptibility map was investigated in this study, and the subject is open to discussion. For this purpose, a series of stability analyses based on circular failure and infinite slope model were performed considering different pseudostatic conditions. The results of analyses show that gentle slopes have higher susceptibility to failure than steeper ones, even if their stability conditions (susceptibilities) are similar for static condition. The seismic forces acting on failure surfaces may not be sufficiently taken into consideration in the conventionally prepared landslide susceptibility maps. Employing the general decreasing trend in stability condition based on slope face angle and the seismic acceleration, a new procedure was introduced for preparing of the landslide susceptibility map for a scenario earthquake. The prediction performance of occurring landslides increased after the procedure was applied to the conventionally prepared landslide susceptibility map. According to the threshold independent spatial performance analyses of the proposed methodology and the produced landslide susceptibility maps, the area under ROC curve values were calculated as 0.801, 0.933, and 0.947 for the maps prepared by considering conventional method and scenario earthquakes having M w values of 5.5 and 7.5, respectively. 相似文献
9.
以玉树7.1级地震诱发的玉树机场路堆积层滑坡为对象,该滑坡坡度约为10o,长×宽×厚为317 m×482 m×19.8 m,由以碎石土为主的上覆层、卵石土为主的滑动带及基岩3层组成,开展大型振动台模型试验,探究震后边坡再次承受振动荷载的能力以及地震垂直分量对坡体稳定性的贡献,分析其动力响应特征和失稳破坏机制。结果表明,强震作用下堆积层滑坡的永久变形是造成地震地质灾害的重要因素;随着输入地震荷载增大,坡脚率先破碎沉降,坡体中部产生弧形裂隙并产生沉降,坡顶出现贯穿张裂隙和剪切裂隙并向坡腰推进,表现出典型的牵引性滑坡特征;峰值加速度(PGA)、动土压力以及加速度频谱与输入地震波的强度、滑坡高程呈正相关;PGA放大系数呈现出明显的非线性特征,其变化趋势随地震荷载强度增大而减小,地震波垂直分量对滑坡PGA放大系数影响略大于水平分量。 相似文献
10.
Semi-empirical models based on Newmark’s sliding block permit the estimation of expected co-seismic displacements in relation to one or more parameters which characterize the ground motion that theoretically caused them. Taking this into consideration, a regression analysis, based on a double-phase viscoplastic (DPV) model, was developed using 96 Italian ground motion accelerograms for a total of 1,448 combinations obtained for different parametric conditions of the indefinite slope model. Repeated stability analysis, performed by means of the DPV model, allows for the assessment of the seismic instability of a slope in relation to different reached behaviour levels, as well as seismically induced permanent displacements. At these behaviour levels, co-seismic increases and possible subsequent decreases of viscoplastic shear strengths are associated. This implies that the post-seismic persistent mobility (collapse) of the slope can be obtained from the computation. On the other hand, coherently with the increasing of shear resistances during fast sliding displacements in clay soils, the seismic-forced displacements result substantially lower than corresponding values obtained by means of the rigorous Newmark’s sliding block. In addition, in relation to some seismic ground motion parameters, regression and functional border and separation curves were obtained with the aim of providing an expeditious seismic slope stability evaluation in reference to the co-seismic and post-seismic behaviour of clayey slopes. Regarding this, the real behaviour of two historical landslide events is discussed in the light of the results of the regression analysis outlined in this work. 相似文献
11.
Advanced seismic slope stability analysis 总被引：2，自引：1，他引：1
The objective of this study was to present an advanced methodology for assessing seismic slope stability by taking into account the uncertainties related to the main input parameters. The methodology was applied on a real landslide in order to show the advantages of using the proposed procedure and establish the baseline trends of dynamic response and calculated permanent seismic displacements. It involves the following steps: preliminary analysis, probabilistic static and seismic factor of safety analysis, and permanent seismic displacement analysis. Estimating post-failure maximum seismic deformation of landslide mass and sounding properties is the most important part of this study. It involves both Newmark sliding block method and continuum mechanics approach, applied for characteristic set of input values in order to have more accurate assessment of slope performance and determine the relative importance of input parameters. The results of the analysis showed the benefits of using the proposed step-by-step methodology. The obtained difference in the results between the two methods depends strongly on the set input data for a particular analysis. 相似文献
12.
A failed slope may not necessarily require a remedial treatment if it can be shown with confidence that the maximum movement
of the slide mass will be within tolerable limits, i.e., not cause loss of life or property. A permanent displacement analysis
of a landslide for static and seismic conditions is presented using a continuum mechanics approach. Computed values of displacement
for static conditions compare favorably with field measurements and computed values of seismic displacements for a postulated
earthquake motion appear reasonable. Also, the seismic displacements using the continuum mechanics approach compare favorably
with those obtained using the Newmark sliding block procedure for assessing seismically-induced slope deformations. 相似文献
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小坡度海底土层地震液化诱发滑移分析方法 总被引：1，自引：0，他引：1
地震可使海底砂质、粉质土层液化并导致上部土层的滑移。基于有效应力有限元动力分析方法和Newmark刚性滑块理论,提出了一种计算海底小坡度（≤5o）土层地震液化引起侧向滑移的简化方法。该方法将波浪荷载简化为海底恒定的上覆压力和初始孔压,忽略了海水粘性对海底土层地震反应的影响,利用改进的Seed孔压模型进行动力分析和液化判别,用Newmark滑块理论计算了土层侧向滑移。通过算例和对比分析,研究了海水深度和土层坡度对侧向滑移的影响,表明该方法的有效性,可为近海工程场地地震地质灾害评价提供参考数据。 相似文献
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应用概率地震危险性评价模型进行地震滑坡危险性区划,是解决潜在地震诱发滑坡危险性评价中震源不确定性与诱发滑坡时空不确定性的有效方法.通过理论分析,结合鲁甸地震区的实际情况,对基于力学原理的Newmark滑块位移模型与概率地震滑坡危险性分析方法中的参数的不确定性问题进行了分析,将斜坡岩土体地震作用下的强度衰减效应、地震加速度地形放大效应、断层破碎带效应融合到了斜坡累积位移计算模型中,进行了模型计算参数的优化.改进后的分析模型,更好地反映了高陡斜坡地形与断层破碎带对地震滑坡灾害发育的控制作用,在鲁甸地震区域滑坡应用中,优化模型中的滑坡失稳极高风险区与实际地震滑坡分布表现出了较好的一致性,在超越概率2%的滑坡失稳概率分布中,鲁甸地区包谷垴—小河断裂、鲁甸—昭通断裂带及牛栏江河谷地带地震滑坡高—极高风险区分布面积增幅十分显著.因此,在Newmark滑块位移模型中考虑地震动参数与岩土参数动态响应规律与变量间的定量关系,对于提高区域斜坡稳定性分析的可靠性具有重要意义. 相似文献
16.
充分考虑振动台实验揭示出来的基本地震滑坡单元体震动滑移特征,总结得到其永久位移的估算方法:（1）考虑地震动惯性力和重力的联合作用,计算相应向上和向下滑移的屈服加速度,以反应其可能向上和向下滑移的行为;（2）在适度简化斜坡岩土体动力学模型的基础上,考虑斜坡岩土体自振特性和滑体所在高度对地震波的放大效应,得到滑体附近的局部地震加速度;（3）考虑滑体附近局部加速度和滑移屈服加速度的控制作用,计算每一地震波的周期内滑体相对滑床所能达到的最大滑移速度（向上和向下）,进而得到相对动能;（4）考虑到滑体的动能基本耗散在滑带上,基于能量守恒原理,将相对动能除以滑带上的摩擦力,即可估算出每一周期内的永久位移;（5）将每一地震波周期内产生的永久位移相累加,即可得到总体的滑动位移。经与实验结果对比,本估算方法具有较高的精度与可靠性,虽只考虑了水平向地震动作用的影响,但对于存在竖向地震动的情况,其思路同样适用,只是需要计入竖向地震动惯性作用力的影响。 相似文献
17.
为研究地震作用下锚固系统的动力响应,采用振动台进行格构梁锚杆支护滑坡模型试验。试验分别输入汶川波、EL Centro波、正弦波作为地震激励,监测锚杆轴力、坡体加速度和位移时程,研究锚固滑坡在地震作用下的动力响应差别、不同位置锚杆在地震作用下的受力机制。结果表明：低量级地震波（0.05 g～0.40 g）作用下,坡脚相对坡体的其他部位,浅表效应表现明显,坡脚滑面由于反复的揉搓作用,更容易出现裂缝,影响整个锚固体的稳定;建议在拟静力法设计的基础上,在滑坡坡脚密集地打入短锚杆或土钉以平衡坡脚滑面处出现的不协调往复运动。高量级地震波作用（0.6 g～0.8 g）下,坡肩处坡表效应表现明显、坡顶滑面处裂缝宽度不断增长,更易出现崩裂、崩滑等现象;建议加长坡顶的第1排锚杆,以抑制坡顶滑面处裂缝的下切发展;同时在坡顶面垂直地打入短锚杆或种植根系发达的植物护坡。格构梁锚固系统不会出现素土边坡的整体性破坏,强震作用下,首先是坡脚锚杆的承载能力受到损伤,顶层锚杆的抗拉力则因坡顶面及上表面的拉裂急剧增长。研究结果为更加合理地进行锚杆抗震设计提供了良好的基础。 相似文献
18.
桩板式抗滑挡墙地震响应的振动台试验研究 总被引：2，自引：0，他引：2
汶川地震路基震害调查表明,在顺层或堆积体边坡中的桩板式抗滑挡墙具有良好的抗震性能。为了更好地了解该结构的抗震性能和优化抗震设计方法,以大型振动台模型试验为手段对其进行研究。为明确地震作用下桩板式抗滑挡墙的地震响应特性,试验采用缩尺的卧龙台站实测地震波对模型激励。试验结果揭示了土压力沿桩身分布规律、桩体位移和边坡岩土体加速度的地震响应特征。研究表明,地震土压力沿桩身呈非线性分布,竖向地震荷载对水平加速度有放大效果。所以,双向加载时的地震土压力比水平单向加载时大,但二者差距在地震基本烈度VII、VIII度区域不显著。滑坡推力、滑床对桩的土体抗力和桩身位移均与输入地震动峰值加速度成正比,即随着地震动峰值加速度的增加,加速度放大比增大;滑动面材料剪切强度折减,滑坡推力、土体抗力和抗身位移均增大,且增大速率加快。此外,结合试验成果,建议了桩板式抗滑挡墙设计时地震综合影响系数Cz的合理取值,对应地震基本烈度VII、VIII、IX度区分别为0.2、0.35、0.4。试验结果有助于揭示该结构抗震机制,也为其抗震设计提供了可靠依据。 相似文献
19.
Constantine A. Stamatopoulos 《Landslides》2009,6(3):191-207
The paper first proposes and validates a constitutive model simulating the change of resistance along a slip surface of clay
for both the undrained and drained cases. The proposed model is based on (a) the critical state theory and (b) the assumption
that the critical state changes once failure is reached, in terms of the further shear displacement. Under undrained conditions,
the proposed model simulates the excess pore pressure generation and, subsequently, the continuous change of resistance along
the slip surface from its initial value to the peak strength and then, at large displacement, the residual value. The latter
can be measured in constant-volume ring shear tests. Then, the developed constitutive model is implemented in the multi-block
sliding system model for the prediction of the triggering and deformation of slides. The improved model is applied at the
well-documented Fourth Avenue landslide of the 1964 Alaska earthquake. 相似文献
20.
This paper presents the development, calibration, and validation of a smoothed particle hydrodynamics (SPH) model for the simulation of seismically induced slope deformation under undrained condition. A constitutive model that combines the isotropic strain softening viscoplasticity and the modified Kondner and Zelasko rule is developed and implemented into SPH formulations. The developed SPH model accounts for the effects of wave propagation in the sliding mass, cyclic nonlinear behavior of soil, and progressive reduction in shear strength during sliding, which are not explicitly considered in various Newmark‐type analyses widely used in the current research and practice in geotechnical earthquake engineering. Soil parameters needed for the developed model can be calibrated using typical laboratory shear strength tests, and experimental or empirical shear modulus reduction curve and damping curve. The strain‐rate effects on soil strength are considered. The developed SPH model is validated against a readily available and well‐documented model slope test on a shaking table. The model simulated slope failure mode, acceleration response spectra, and slope deformations are in excellent agreement with the experimental data. It is thus suggested that the developed SPH model may be utilized to reliably simulate earthquake‐induced slope deformations. This paper also indicates that if implemented with appropriate constitutive models, SPH method can be used to model large‐deformation problems with high fidelity. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献