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在国内外岩土模型动力试验中，一般以图表形式对监测区域进行逐一动态分析，无法直观形象的掌握试验模型整体受力变形，为深入分析动态响应机理带来一定的不便。以前-后排抗滑桩加固斜坡桥基的大型振动台模型试验为例，通过在岩土体中埋设一定数量的自制磷青铜带和水平加速度计，监测滑坡变形和加速度响应，结合已知测点的水平坐标和竖向坐标，利用Renka Cline随机矩阵生成方法转换为数字矩阵形式，据此绘制坡体变形及PGA放大系数的二维等势图。试验结果显示，二维等势图能合理反映斜坡PGA放大系数的变化规律，揭示振动波作用下斜坡变形破坏的基本特征，研究结论和试验现象保持一致，满足斜坡模型整体受力变形分析的基本要求，可以作为一种实用的试验分析方法。 相似文献
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干海子滑坡位于大渡河流域,规模巨大。为研究该滑坡的稳定性,在对滑坡基本特征及变形破坏特征等深入研究的基础上,采用极限平衡法（Geo-slope软件）和有限差分法（FLAC-3D软件）对该滑坡的稳定性和应力应变特征进行了计算、模拟。稳定性计算模拟主要从深层、浅层及局部稳定三方面入手分析,计算模拟结果与滑坡的宏观地质现象均具有较高的吻合度。通过对该滑坡定性与定量的稳定性分析,判断其浅层滑体在暴雨工况下将处于极限平衡状态,而深层滑体在地震工况下依旧处于基本稳定状态,所得结论为下一步滑坡防治工作提供了翔实的依据。 相似文献
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边坡破坏是累积性过程，从变形到破坏的过程中会产生永久位移，如果永久位移过大，极有可能产生滑坡。因此根据不同工况下采集到的位移数据，分析地震作用下反倾层状岩质边坡在不同内摩擦角下的破坏特征。利用二维数值流形法（NMM），以青藏高原金沙江流域西藏昌都地区芒康县索多西乡贡扎倾倒滑坡为研究对象，依据实地考察数据及室内力学试验得到的物理力学参数，建立数值计算模型，模拟地震作用下反倾层状岩质边坡倾倒破坏过程，并在边坡上布置3组监测点获取位移数据。模拟结果表明:随着内摩擦角的增大，边坡坡体从开始破坏到新的平衡状态和达到最大位移所需的时间越短，同时，滑动块体最大水平位移逐渐减小；内摩擦角＜40°时，坡体在前15 s呈整体移动趋势，大部分岩块产生整体滑移，靠近坡顶处的岩块发生轻微转动，推动前面的岩块加速滑动，呈倾倒-滑移模式；内摩擦角＞40°时，靠近坡顶的岩块首先产生滑动，并转动驱使前面的岩块，推动坡脚处岩块产生滑动，最终上部岩块达到新的平衡，呈渐进式倾倒破坏，产生整体性破坏的可能性较小。 相似文献
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基于室内试验获取黄土滑坡的静力和动力力学强度参数,建立低角度黄土滑坡破坏大型物理模拟试验模型,结合FLAC3D有限差分软件,分析黄土滑坡的动力响应规律和宏观破坏特性,阐明在地震作用下黄土滑坡的失稳演化规律,揭示黄土滑坡滑体运动迁移路径。结果表明：低角度黄土-泥岩滑坡在地震荷载作用下地震波水平方向和垂直方向均出现明显的放大效应;在黄土层内部,随着斜坡高度增加,坡肩和斜坡后缘加速度放大效应较为明显,对比坡脚、坡腰和坡肩处剖面上加速度放大系数,下伏泥岩对地震波产生一定的放大效应。松弛拉张裂隙,土体强度降低,接触面和坡肩、斜坡后缘处的拉张裂缝形成弧形滑移面,上覆黄土层由内向外依次连带下滑,坡肩处土体的下滑力和地震力促使坡腰土体大面积长距离滑动,最大滑动涉及范围长达200 m左右,土体下滑至坡脚发生堆积并产生隆起。数值模拟结果和振动台试验结果在动力响应和宏观变形破坏特征均呈现较高的吻合度。 相似文献
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福泉滑坡具有顺倾上硬下软的结构特征,采用颗粒流离散元模拟采动滑坡的变形破坏全过程,研究福泉滑坡在露天开采条件下变形破坏的地质力学模式。基于颗粒流离散元程序,引入平行粘结模型,通过参数标定确定细观参数与宏观力学性质的关系,据此建立斜坡模型,模拟斜坡采动过程中的变形破坏全过程,确定该类采动滑坡形成的地质力学模式;研究滑坡滑动过程中的速度和能量变化以及堆积特征。研究表明:斜坡采动过程中,潜在滑面顺层滑移,后缘拉裂,裂纹从下往上向软弱面拓展,前缘坡脚处岩体形成锁固段,斜坡出现由前缘至后缘缘递减的蠕滑变形,随着斜坡进一步采动,锁固段发生剪切破坏,前缘坡体启动,中后部裂缝贯通—滑移,斜坡整体失稳破坏,形成牵引式采动滑坡,该类滑坡形成的地质力学模式可分为:滑移—拉裂—剪断3个阶段;对滑坡运动过程的模拟可知,采坑积水是小坝组受灾的关键转化因子。 相似文献
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Grass hedges are narrow strips of stiff‐stemmed vegetation used to control erosion and sediment delivery. When planted on the contour, the hydraulic resistance of the vegetation slows runoff, creates ponding, and promotes sediment deposition. When tillage is performed between grass hedges, soil may be thrown against the vegetation, where it settles to form a berm within the hedge. Tillage‐induced berms divert part of runoff, causing it to flow alongside the hedge without crossing it. Such flow partitioning created by grass hedges was measured on experimental plots located on silt loam loess soil near Holly Springs, Mississippi, USA, where hedges planted at the bottom of 5%, 22.1‐m‐long slopes evolved berms averaging 0.13 m in height. They diverted about 80% of the runoff for events smaller than 5 mm and about 50% for large events. A two‐dimensional model was developed to determine overland flow patterns over complex terrains, accounting for oriented roughness created by tillage corrugations, crop rows, and larger features such as berms and vegetative barriers. The model was used to reproduce the flow partition observed in the field experiments and to determine how berm height and slope steepness and length affected runoff redistribution. Numerical simulations indicated that for most runoff events, ponded runoff depths were not high enough to overtop the berm but rather crossed the berms through cracks and gaps, represented in the model as small triangular weirs. The model also was applied to a 6.0‐ha watershed in Western Iowa, USA, where nine grass hedges were planted across 12–16% slopes. Computed dynamic flow properties showed that berms increased the amount of runoff flowing laterally upslope of the hedges and that a large portion of the runoff crossed the vegetative strips at a few locations and with high flow depths, increasing the risk of development of ephemeral gullies. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Introduction China is a country with many landslides and debris flows. These disasters bring out a large amount of losses of life and property. It is significant to predict landslide incident by monitoring the deformations of these landslides. At past, triangulation and trilateration are traditional tools, but it is very difficult for them to realize real-time monitoring, and it is more dangerous for obser- vation workers when the deformation becomes larger. Because of many advantages such as… 相似文献
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To the progressive landslide, development of the internal deformation and failure situation can’t be accurately reflected by the overall stability of coefficients and failure probability. But this problem can be solved by utilizing the principle of progressive failure by slices. Taking the warning area of Baishuihe landslide as an example, 5 days accumulated rainfall in different reappearing period is computed by Gumbel model. The failure probability of each slice is calculated by progressive failure principle, which is based on Monte Carlo model. The following results can be revealed through calculation: Overall stability and failure probability can’t reflect real situation of Baishuihe landslide warning area. Through building the calculation of progressive failure model of each slice, the stability of each part in the Baishuihe landslide warning area is quite different. Unstable region mainly lies in vicinity of the middle and posterior warning area. The front of the warning area remains stable. Deformation characteristics of the warning area are consistent with the investigation report. The scope of unstable area increased gradually with rainfall and the decline of reservoir water. Under 5 day’s accumulated rainfall of 50 years, the poor stable and unstable region reached 75 %, there is a large possibility of local deformation slip. Under the joint action of rainfall and reservoir water level, the warning area of Baishuihe landslide shows a progressive failure mode from top to bottom. 相似文献
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针对基于机器学习的滑坡易发性评价中非滑坡样本选取不规范导致的分类精度较低问题,本文提出联合基于密度的噪声应用空间聚类（Density-Based Spatial Clustering of Applications with Noise,DBSCAN）采样策略和支持向量机（Support Vector Machine,SVM）分类方法的DBSCAN-SVM滑坡易发性评价模型。首先,基于DBSCAN聚类和空间分析选取非滑坡样本;然后,将样本数据代入SVM分类模型进行训练与验证,预测并提取SVM分类中属于滑坡的概率,获得滑坡易发性;最后,以四川省绵阳市为试验区,预测滑坡易发性概率,基于滑坡易发性精度与分级结果等要素,与传统非滑坡样本采集策略的SVM滑坡易发性评价模型进行对比,并结合实际情况对DBSCAN-SVM模型评价结果进行分析。研究结果表明,相比传统SVM滑坡易发性评价模型,本文提出的DBSCAN-SVM滑坡易发性评价模型在高易发区和极高易发区中包含的滑坡样本数量较多,准确率、召回率、AUC、F1分数均得到提高,精度较高。 相似文献
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在滑坡变形较大时，常规GPS静态观测方式满足不了滑坡实时监测的需要. 本文结合滑坡变形的特点，利用GPS单历元定位新方法frac34;单历元阻尼LAMBDA方法，对滑坡实时形变进行了监测试验. 该方法不需要考虑GPS载波相位测量中棘手的周跳问题，每一历元即可搜索到正确的整周模糊度，从而获得监测点厘米级精度的坐标. 采用平滑方法后可以分辨出毫米级精度的坐标和滑动速度，扩大了GPS形变监测的应用范围. 本文简要介绍了新方法的原理，并使用低价位的单频GPS接收机，在江西省一个实测滑坡中取得了较好的应用效果. 相似文献
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Peter R. Robichaud Frederick B. Pierson Robert E. Brown Joseph W. Wagenbrenner 《水文研究》2008,22(2):159-170
After the Valley Complex Fire burned 86 000 ha in western Montana in 2000, two studies were conducted to determine the effectiveness of contour‐felled log, straw wattle, and hand‐dug contour trench erosion barriers in mitigating postfire runoff and erosion. Sixteen plots were located across a steep, severely burned slope, with a single barrier installed in 12 plots (four per treatment) and four plots left untreated as controls. In a rainfall‐plus‐inflow simulation, 26 mm h?1 rainfall was applied to each plot for 1 h and 48 L min?1 of overland flow was added for the last 15 min. Total runoff from the contour‐felled log (0·58 mm) and straw wattle (0·40 mm) plots was significantly less than from the control plots (2·0 mm), but the contour trench plots (1·3 mm) showed no difference. The total sediment yield from the straw wattle plots (0·21 Mg ha?1) was significantly less than the control plots (2·2 Mg ha?1); the sediment yields in the contour‐felled log plots (0·58 Mg ha?1) and the contour trench plots (2·5 Mg ha?1) were not significantly different. After the simulations, sediment fences were installed to trap sediment eroded by natural rainfall. During the subsequent 3 years, sediment yields from individual events increased significantly with increasing 10 min maximum intensity and rainfall amounts. High‐intensity rainfall occurred early in the study and the erosion barriers were filled with sediment. There were no significant differences in event or annual sediment yields among treated and control plots. In 2001, the overall mean annual sediment yield was 21 Mg ha?1; this value declined significantly to 0·6 Mg ha?1 in 2002 and 0·2 Mg ha?1 in 2003. The erosion barrier sediment storage used was less than the total available storage capacity; runoff and sediment were observed going over the top and around the ends of the barriers even when the barriers were less than half filled. Published in 2007 by John Wiley & Sons, Ltd. 相似文献
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桥台在桥梁系统中占据重要位置,桥台的稳定性直接影响到桥梁的抗震性能。在国内外大量震害中发现大量由桥台破坏引起的桥梁损坏,而且这些破坏常常伴随着由于液化引起的地面大变形。为研究液化场地中桥台滑坡机理,采用完全耦合的有效应力分析方法,利用修正的PasterZienkiewicz Mark-Ⅲ模型来模拟砂土在地震荷载作用下的液化特性。研究台顶梁重和液化层位置对桥台位移的影响,并分析夯实作用对砂土液化的影响。结果表明:模拟得出结果与振动台试验结果基本一致,而且简单的夯实不能降低砂土液化的风险。 相似文献
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地震滑坡危险性评估可为震后应急响应等提供科学的决策依据。纽马克位移法可不依赖同震滑坡编目快速评估同震滑坡危险性。工程岩体物理力学参数是该方法的核心参数之一,但其赋值过于单一,难以反映复杂地质背景下岩体强度的空间差异性。针对上述问题,本文在分析地震滑坡影响因子的基础上,选择距断层距离、高程和距水系距离作为影响岩体强度的评价指标并建立岩体强度评价模型,获得区域岩体强度修正系数,进而修正传统方法的临界加速度。结合震后的即时地震动峰值加速度,采用简化纽马克位移法计算边坡累积位移,开展地震滑坡危险性快速评估,并以汶川MW7.9地震的地震滑坡危险性评估为例验证本文方法。结果表明,相对于传统方法,本文方法划分的地震滑坡危险区与同震滑坡分布更加一致。 相似文献
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The large-scale deformation of high mountain slopes finds its origin in many phenomena with very different time-constants. Gravitational effect, tectonic forces, and water infiltration are generally the principal causes. However, it is always very difficult to distinguish which cause is dominant and which are their respective effects. A two-dimensional numerical experiment coupled with geophysical approach was carried out to determine (1) the effect of gravitational force on the mechanical behaviour of the “la Clapière” area, (2) a 2D-depth structure of this landslide. The results show that gravitational instability is possible and leads to destabilisation of the massif by a regressive evolution of the landslide from the bottom at 1100 m up to a height of 1800 m, which is actually the top of the La Clapière landslide. This deformation progression only concerns a depth of around 150 ± 50 m, which can be correlated to the sliding surface, as suggested by our electrical data obtained by resistivity investigations and previous studies. Our numerical results suggest that changes of the slope topography “drive” the diffusion of the plastic deformation in the mass, possibly through a channel which could be then the privileged zone along which the fracture is initiated. 相似文献
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通过大型地质力学模型试验,研究在无支挡结构下降雨对隧道-滑坡正交体系的作用机理。主要研究不同降雨阶段,隧道-滑坡正交体系下隧道纵向应变的变化特征及隧道不同横断面环向应力变化特点,并重点分析在不同降雨阶段,不同位置及其不同横断面滑体的位移变化特征。试验结果表明:(1)降雨可导致坡体横断面断裂而出现新的滑移面,从而导致坡体失稳。(2)在隧道-滑坡正交体系下,随着雨水的下渗及滑体土样含水率不断增大,隧道局部应变有明显突变,且山侧纵向应变比河侧应变要大。(3)在隧道-滑坡正交体系下,降雨使得隧道环向应力呈不均匀变化:隧道的底部应力大于顶部应力,山侧应力大于河侧应力,表明降雨可导致滑体蠕动或局部滑移,引起隧道不均匀受力及变形,这对隧道结构的安全非常不利。本次试验可为雨水充沛区的滑坡及隧道抗滑设计提供一定参考。 相似文献
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Complementary geophysical surveys on large landslides help revealgeologic structures and processes, and thus can help devise mitigation strategies. The combined interpretation of these methods enhance the result of each data set interpretation and makes it possible to derive a geological model of the landslide.We chose a test site on the Boup landslide (Wallis, western SwissAlps) to test high-resolution seismic reflection surveyscombined with ground penetratingradar (GPR), electromagnetic (EM) and electrokinetic spontaneous potential (SP) measurements.The results of the high-resolution seismic surveys suggest thatthe sliding is within a gypsum layer at 50 m depth and not as previously believed along a deeper (70 m) gypsum-shale boundary, also mapped seismically. Inversion of electromagnetic profiles (EM-34) with constraints from seismic data provided a model cross-section of conductivity values of the landslide (20–25 mS/m) and of the surrounding stable ground (10–15 mS/m), and it helped outline their boundary at depth.The accurate surface location of the landslide limit could be detected withelectromagnetic measurements of shallower depths of investigation (EM-31). Positive PS anomalies revealed an upward flow of mineralised water interpreted to follow the lateral boundary of the Boup landslide on its east side. Limited success was obtained withGPR profiling. This method can be hampered by conductive shallow layers, and itssuccessful application on landslides is expected to be strongly site dependant. 相似文献
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How does forest structure affect root reinforcement and susceptibility to shallow landslides? 
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下载免费PDF全文 Christine Moos Peter Bebi Frank Graf Josias Mattli Christian Rickli Massimiliano Schwarz 《地球表面变化过程与地形》2016,41(7):951-960
Forests can decrease the risk of shallow landslides by mechanically reinforcing the soil and positively influencing its water balance. However, little is known about the effect of different forest structures on slope stability. In the study area in St Antönien, Switzerland, we applied statistical prediction models and a physically‐based model for spatial distribution of root reinforcement in order to quantify the influence of forest structure on slope stability. We designed a generalized linear regression model and a random forest model including variables describing forest structure along with terrain parameters for a set of landslide and control points facing similar slope angle and tree coverage. The root distribution measured at regular distances from seven trees in the same study area was used to calibrate a root distribution model. The root reinforcement was calculated as a function of tree dimension and distance from tree with the root bundle model (RBMw). Based on the modelled values of root reinforcement, we introduced a proxy‐variable for root reinforcement of the nearest tree using a gamma distribution. The results of the statistical analysis show that variables related to forest structure significantly influence landslide susceptibility along with terrain parameters. Significant effects were found for gap length, the distance to the nearest trees and the proxy‐variable for root reinforcement of the nearest tree. Gaps longer than 20 m critically increased the susceptibility to landslides. Root reinforcement decreased with increasing distance from trees and is smaller in landslide plots compared to control plots. Furthermore, the influence of forest structure strongly depends on geomorphological and hydrological conditions. Our results enhance the quantitative knowledge about the influence of forest structure on root reinforcement and landslide susceptibility and support existing management recommendations for protection against gravitational natural hazards. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献