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1.
In the present paper, a finite element approach is proposed to analyse the mobility of active landslides which are controlled by groundwater fluctuations within the slope. These landslides are usually characterised by low displacement rates with deformations that are essentially concentrated within a narrow shear zone above which the unstable soil mass moves with deformations of no great concern. The proposed approach utilises an elasto-viscoplastic constitutive model in conjunction with a Mohr-Coulomb yield function to describe the behaviour of the soil in the shear zone. For the other soils involved by the landslide, an elastic model is used for the sake of simplicity. A significant advantage of the present method lies in the fact that few constitutive parameters are required as input data, the most of which can be readily obtained by conventional geotechnical tests. The rest of the required parameters should be calibrated on the basis of the available monitoring data concerning the change in the piezometric levels and the associated movements of the unstable soil mass. After being calibrated and validated, the proposed approach can be used to predict future landslide movements owing to expected groundwater fluctuations or to assess the effectiveness of drainage systems which are designed to control the landslide mobility. The method is applied to back-predict the observed field behaviour of three active slow-moving landslides documented in the literature. 相似文献
2.
强降雨可诱发新近纪软岩质滑坡滑移变形。1955年至今,降雨在陕西宝鸡诱发超过十起大型滑坡灾害。2011年9月19日,宝鸡市区72 h内的降雨量达到332 mm,北坡金鼎寺、簸箕山与高家崖滑坡出现裂缝,威胁市区居民安全。为分析滑坡的变形机制与降雨触发的滑体内地下水位的波动关系,2012—2015年,开展了降雨量、地下水位、孔隙水压力、滑坡应力与位移等物理量的实时监测,统计分析了它们的频率、活动强度及累积变化规律,提出了滑坡的位移扩展模型。研究显示:(1)地下水的活动会影响新近纪软岩质滑坡的变形,但降雨量、地下水位、孔隙水压力、滑坡体应力与位移等物理量变化机制有差异,地下水位、孔隙水压力呈周期性变化,滑坡体的应力、位移的变化具有累积效应;(2)宝鸡市北坡滑坡运动变形具有蠕变、快速滑移两个阶段。降雨会触发的滑坡体各物理量出现加速变化,地下水位波动幅度为0.27~1m,孔隙水压力的变化幅度为10kPa,滑体浅层的水平应力变化幅度为5.6kPa;(3)在判断降雨能否诱发滑坡快速滑移过程中,既需分析滑体应力、位移变化的累积效应,又需分析新近纪软岩质滑带的摩擦破坏机制。 相似文献
3.
Landslides are mainly triggered by decrease in the matric suction with deepening the wetting band by rainfall infiltrations. This paper reports rainfall-induced landslides in partially saturated soil slopes through a field study. A comprehensive analysis on Umyeonsan (Mt.) landslides in 2011 was highlighted. The incident involves the collapse of unsaturated soil slopes under extreme-rainfall event. Fundamental studies on the mechanism and the cause of landslides were carried out. A number of technical findings are of interest, including the failure mechanism of a depth of soil and effect of groundwater flow, the downward movement of wetting band and the increase of groundwater level. Based on this, an integrated analysis methodology for a rainfall-induced landslide is proposed in this paper that incorporates the field matric suction for obtaining hydraulic parameters of unsaturated soil. The field matric suction is shown to govern the rate of change in the water infiltration for the landslide analysis with respect to an antecedent rainfall. Special attention was given to a one-dimensional infiltration model to determine the wetting band depth in the absence of the field matric suction. The results indicate that landslide activities were primarily dependent on rainfall infiltration, soil properties, slope geometries, vegetation, and groundwater table positions. The proposed methodology has clearly demonstrated both shallow and deep-seated landslides and shows good agreement with the results of landslide investigations. 相似文献
4.
Using an extreme learning machine to predict the displacement of step-like landslides in relation to controlling factors 总被引：4，自引：2，他引：2
In the evolution of landslides, besides the geological conditions, displacement depends on the variation of the controlling factors. Due to the periodic fluctuation of the reservoir water level and the precipitation, the shape of cumulative displacement-time curves of the colluvial landslides in the Three Gorges Reservoir follows a step function. The Baijiabao landslide in the Three Gorges region was selected as a case study. By analysing the response relationship between the landslide deformation, the rainfall, the reservoir water level and the groundwater level, an extreme learning machine was proposed in order to establish the landslide displacement prediction model in relation to controlling factors. The result demonstrated that the curves of the predicted and measured values were very similar, with a correlation coefficient of 0.984. They showed a distinctive step-like deformation characteristic, which underlined the role of the influencing factors in the displacement of the landslide. In relation to controlling factors, the proposed extreme learning machine (ELM) model showed a great ability to predict the Baijiabao landslide and is thus an effective displacement prediction method for colluvial landslides with step-like deformation in the Three Gorges Reservoir region. 相似文献
5.
《China Geology》2020,3(3):455-461
Many landslide disasters, which tend to result in significant damage, are caused by typhoon-triggered rainstorms. In this case, it is very important to study the dynamic characteristics of the hydrological response of landslide bodies since it enables the early warning and prediction of landslide disasters in typhoon periods. To investigate the dynamic mechanisms of groundwater in a landslide body under typhoon-triggered rainstorm conditions, the authors selected the landslide occurring in Zhonglin Village, Wencheng County, China (also referred to as Zhonglin Village landslide) as a case study. The transient seepage field characteristics of groundwater in the landslide body were simulated with two different rainfall models by using the finite element method (FEM). The research results show that the impact of typhoon-triggered rainstorms on landslides can be divided into three stages: (i) Rapid rise of groundwater level; (ii) infiltration of groundwater from the surface to deeper level, and (iii) surface runoff erosion. Moreover, the infiltration rate of groundwater in the landslide body is mainly affected by the intensity of typhoon-induced rainfall. It can be deduced that higher rainfall intensity leads to a greater potential difference and a higher infiltration rate. The rainfall intensity also determines the development mode of landslide deformation and destruction. 相似文献
6.
On Shikoku Island, which is one of the four main islands of Japan, a large number of large-scale crystalline schist landslides have been revealed and are being monitored by an observation system. Seasonal heavy rainfall is the most active meteorological factor that can threaten the stability of this kind of site-specific landslide. In this paper, on the basis of the study of the rainfall-related behavior of a typical crystalline schist landslide, the Zentoku landslide, by analyzing the precisely and continuously observed piezometric and movement data, a method was developed to quantitatively assess the effect of heavy rainfall on a large-scale landslide. The results indicated that heavy rainfall-induced landslide displacement shows good correlation with the variation of groundwater levels. Variations of groundwater level have been simulated with the use of a tank model. The simulation using this model permits the change in water levels for future rainfall events to be predicted. By combining the predicted results with the empirical relation between displacements and water levels, rainfall-induced landslide movement during extreme rainfall events can be estimated in advance. The effect of heavy rainfall on sliding behavior can be quantified in terms of the change in displacement. Thus warning information or advisories for the local residents can be provided. 相似文献
7.
基于滑带应力状态分析和室内试验,提出了基于滑带强度参数动态演化的滑坡稳定性评价方法,并将应力状态作为评价滑面力学参数的主要指标,以合理地反映滑面强度状态对滑坡稳定性的影响。通过室内试验,获得了滑面强度参数与工程性状、力学参数之间的量化关系,在该基础上,通过数值计算,对滑面的力学参数和滑坡的稳定性进行三维计算。计算结果表明,利用提出的方法能较好地反映出滑带强度参数的空间分区特征。同时,对工况变动情况下滑带的强度参数进行量化取值,并对滑坡的稳定性进行动态计算,提出的计算方法更能体现出滑坡力学参数与稳定性的动态变化过程。 相似文献
8.
Prediction of ground displacements and velocities from groundwater level changes at the Vallcebre landslide (Eastern Pyrenees, Spain) 总被引：2，自引：5，他引：2
In active landslides, the prediction of acceleration of movement is a crucial issue for the design and performance of warning systems. The landslide of Vallcebre in the Eastern Pyreenes, Spain, has been monitored since 1996 and data on rainfall, groundwater levels and ground displacements are measured on a regular basis. Displacements observed in borehole wire extensometers have shown an immediate response of the landslide to rainfall episodes. This rapid response is likely due to the presence of preferential drainage ways. The occurrence of nearly constant rates of displacement in coincidence with steady groundwater levels suggests the presence of viscous forces developed during the movement. An attempt to predict both landslide displacements and velocities was performed at Vallcebre by solving the momentum equation in which a viscous term (Bingham and power law) was added. Results show that, using similar rheological parameters for the entire landslide, computed displacements reproduce quite accurately the displacements observed at three selected wire extensometers. These results indicate that prediction of displacements from groundwater level changes is feasible. 相似文献
9.
在系统分析滑坡的物质组成和失稳动因的基础上,分析和研究了地下水在滑坡稳定性演化过程中的卸载与加载动力作用及其位移响应规律和特点。从非线性系统动力学角度,提出了运用地下水卸加载动力与位移响应耦合预测参数来评价边坡稳定性演化规律与失稳特征,即以地下水位变化量作为堆积层滑坡的卸加载动力参数,以相应的位移作为其卸加载响应参数,建立和确定了地下水卸加载动力与位移响应比预测参数与评价模型。同时,运用损伤力学基本原理,建立了其卸加载响应比与坡体损伤变量和稳定性系数的定量关系以及失稳判据。以三峡库区典型堆积层滑坡分析为例,运用地下水动力与位移耦合预测模型对其稳定性进行了分析与评价,发现地下水动力位移耦合预测参数变化与边坡稳定性实际动态演化规律基本吻合。研究成果表明,所确定的参数是水诱发型堆积层滑坡的一种有效位移动力评价参数,可运用该参数对该类滑坡的动态稳定性进行实时监测预警与评价。 相似文献
10.
降雨量和位移是当前降雨型滑坡监测预警最常用的指标。然而,降雨量和位移监测结果只能反映降雨作用下滑坡的变形情况,不能揭示滑坡内在物理力学性状对降雨的响应。因此,除降雨量和位移监测之外,建立包括体积含水率、基质吸力等反映滑坡动态演化过程的关键指标监测体系必将成为今后更真实地把握滑坡内在演化趋势、更准确地建立滑坡综合预警判据的最有效手段。笔者对赣南地区典型降雨型滑坡进行了多指标监测及综合预警示范研究。结果表明:(1)在降雨条件下滑坡土体内部体积含水率、基质吸力和温度等多指标均产生有规律的动态响应;(2)随着降雨的持续,滑体体积含水率与基质吸力的变化均具有显著的滞后现象;(3)体积含水率和基质吸力变化速率与滑体位移具有显著的正相关性;(4)滑体温度分布变化规律受大气温度和体积含水率的共同影响。以实测数据的滑坡稳定性分析为基准,在考虑实际降雨入渗深度与滑坡稳定性的关联度上,建立了包括日降雨量、体积含水率增加速率、基质吸力减小速率以及位移速度多元指标预警方法体系,提出了基于关键指标综合预警体系及确定方法,旨在为降雨滑坡准确预警提供新模式。 相似文献
11.
Influences of soil water characteristic curve on rainfall-induced shallow landslides 总被引：3，自引：2，他引：1
Tung-Lin Tsai 《Environmental Earth Sciences》2011,64(2):449-459
The analysis of slope instability induced by rainfall was usually performed using the main drying curve as the measurement
of the main wetting curve is a more time-consuming and costly task. In this study, the influences of the main drying and wetting
curves on rainfall-induced shallow landslides are examined. Three designed scenarios and a real case scenario are used to
conduct this examination. The prediction of shallow landslide occurrence is related to the main drying and wetting curves
due to the strong relation between groundwater pressure head and hysteresis effect. The main wetting curve may have a less
minimum landslide-triggering rainfall amount and a less rainfall duration threshold for landslide occurrence than the drying
wetting curve. For safety’s sake, an underestimation of shallow landslide occurrence may be produced by the commonly used
main drying curve. In addition, besides the shallow landslide occurrence, the failure depth and the time to failure are also
influenced by the main drying and wetting curves. The hysteresis effect should be taken into account for assessing rainfall-induced
shallow landslides. 相似文献
12.
Pham Van Tien Kyoji Sassa Kaoru Takara Hiroshi Fukuoka Khang Dang Tatsuya Shibasaki Nguyen Duc Ha Hendy Setiawan Doan Huy Loi 《Landslides》2018,15(9):1761-1778
Extreme heavy rainfall due to Typhoon Talas on September 2–4, 2011 in the Kii Peninsula, Japan, triggered numerous floods and landslides. This study investigates the mechanism and the entire process of rainfall-induced deep-seated landslides forming two massive dams in the Kuridaira and Akatani valleys, respectively. The mechanism of the rapid deep-seated landslides is examined through a series of laboratory experiments on samples from sliding surfaces by using undrained high-stress dynamic-loading ring-shear apparatus. The test results indicate that the failure of samples is triggered by excess pore water pressure generation under a shear displacement from 2 to 7 mm with a pore pressure ratio ranging from 0.33 to 0.37. The rapid movement of landslides is mainly attributed to high mobility due to the liquefaction behavior of both sandstone-rich and shale samples. Geomorphic settings and landslide mobility are major contributing factors to the dam formation. Additionally, shear displacement control tests show that a certain amount of shear displacement between 2 and 7 mm along the sliding surfaces of the gravitationally deformed slopes might have led to the failures. Importantly, computer simulation with LS-RAPID software using input parameters obtained from physical experiments is employed to interpret the entire formation process of the abovementioned two landslide dams. The simulation results are examined in accordance with the observed on-site geomorphic features and recorded data to explain the possibility of sliding processes. The results further point out that local failures are initiated from the lower middle part of the landslide bodies where the geological boundary exists. This condition most probably influences the landslide initiation in the two case studies. This research is therefore helpful for hazard assessment of slopes that are susceptible to deep-seated landslides and other sequential processes in areas with geology and geomorphology similar to that of the Kii Peninsula. 相似文献
13.
结合三峡库区堆积层滑坡的具体情况讨论了地下水对滑坡的物理化学和力学作用,论证了地下水物理化学作用对三峡库区松散堆积层滑坡稳定性的影响远小于地下水动力作用对滑坡稳定性的影响.在此基础上,引入总压力水头,提出将地下水对滑坡的各种力学作用简化为总压力水头,结合加卸载响应比方法的思路,分别建立了基于库水位涨落和降雨影响的滑坡预... 相似文献
14.
三峡库区地质灾害严重而且多发,其中滑坡灾害问题尤为突出。开展滑坡的模型试验与理论研究对于防灾减灾以及滑坡预报具有重要的价值与意义。以塘角村1号滑坡为例,在充分认识其地质原型的基础上,在室内进行了大量土工试验及水理性质实验(包括野外取样实验及相似材料实验),并根据相似理论优选了该滑坡的相似材料,利用实验室自行研制的地质环境模拟实验装置建立了滑坡地质力学模型; 在滑带土模拟问题上,采用土工模及聚乙烯薄膜取代使模型试验更能与野外相吻合。考虑降雨及地表水体造成滑坡体地下水位变化及控制面抗剪强度削减从而改变其稳定性的过程,设计了2种切合实际的模拟工况进行实验,结合电感调频式传感器结合无纸记录仪实时监测滑坡地表位移、孔隙水压力、土压力等指标的变化情况。结果显示,在暴雨220mmd-1 持续3d后,在库水位下降至169m时,滑坡前缘失稳。最后对滑坡地表位移时间曲线的变形阶段进行划分,可看出滑坡体前缘可从稳定状态直接进入加速蠕变阶段。 相似文献
15.
以福建德化县彭坑滑坡为例,基于非饱和土力学理论,结合滑坡实际监测数据,利用有限元法对坡体在雨水入渗条件下的渗流、变形特性和稳定性进行计算和分析,研究滑坡对降雨的动态响应和不同工况下安全系数和位移的关系。结果表明:滑体结构松散,易于雨水入渗,改变基质吸力空间分布,弱化岩土体参数; 持续降雨会使地下水位上升,坡脚发生变形,牵引坡体后缘产生拉裂,直至在降雨期间产生以非饱和区域为主的滑坡。强降雨初期,边坡安全系数下降较快,易发生滑坡; 雨停后安全系数会因雨水持续下渗而进一步降低,应注意雨后滑坡的产生; 同样水分在不同坡体部位对稳定性影响不同,安全系数有消有涨,存在时空效应。最后为反映地下水位线和降雨条件变化对边坡产生危害的程度,提出危险系数概念,建立危险系数与增量位移的关系,实现边坡测点位移变化的阶段式预警。研究结果和方法可为类似工程的治理和监测预警提供有意义的参考。 相似文献
16.
堆积层滑坡是滑坡的一种基本类型,其物质组成、结构等有别于其它类型滑坡。堆积层滑坡失稳绝大多数是由降雨或地下水位的变化而引起的,在降雨诱发堆积层滑坡稳定性分析中,必须考虑渗透力的作用。系统分析了堆积型滑坡发育环境及特征,推导了基于总应力法和有效应力法的可考虑渗透力的传递系数法,采用有效应力法计算滑坡稳定系数时,既要考虑地下水浮力作用,又要考虑地下水流动时的渗透力作用;采用总应力法计算滑坡稳定系数时,仅需考虑地下水流动时的渗透力作用。对一个工程实例进行了深入剖析,验证了考虑渗透力的传递系数法的可靠性。 相似文献
17.
针对库水位变化条件下滑坡的稳定性定量评价复杂问题,考虑降雨和库水位变化对地下水渗流场变化规律的影响机制,采用饱和-非饱和渗流的基本理论,运用渗流模拟有限元法,对重庆市武隆区羊角滩滑坡在6种不同工况下的库区滑坡的稳定性开展了模拟研究。结果表明: ①降雨工况下,降雨对地下水渗流场都有影响,滑坡中部位置受地下水位影响最大,前后部影响小,降雨条件下,滑坡稳定性随着降雨历时的增加而变小,到达一定阶段后,滑坡已经滑动,滑坡稳定性系数不再变化; ②库水位工况下,主要影响滑坡前缘,地下水位是随库水位变化而迅速变化的,随着库水位的上涨,滑坡稳定性系数呈现先减小后增大的趋势; ③地下水位的骤升对浮托作用影响有限,对压坡作用影响较大,同时降低了渗流力的影响,对滑坡稳定起到了积极作用,地下水位的骤降增大了渗流力,减弱了前缘库水位的压坡作用,滑坡失稳的可能性最大。可为库区该类滑坡的稳定性现状及发展趋势预判提供科学依据。 相似文献
18.
以三舟溪滑坡为例,运用HYDRUS-1D模拟软件,对由于降雨影响造成滑坡土壤不饱和区的土壤水运动进行模拟计算,为滑坡体降雨入渗规律研究提供参考依据。将模拟计算结果与实际监测结果进行对比,发现在考虑降雨影响下,评价滑坡体降雨入渗规律采用Hydrus-1D是可靠的。受降雨特征和初始含水率的影响,降雨对地下水位的影响存在滞后作用,5月25日和5月29日降雨期间,湿润锋到达模型底部所用的时间分别为 6 h、19.2 h。 相似文献
19.
建立高效合理的区域滑坡灾害降雨预警模型对滑坡防治具有重要意义.然而以往的研究多侧重于临滑预警,对蠕变型滑坡在强降雨工况下的短暂加速变形的预警研究还有待深入.以三峡库区云阳县域内滑坡为例,首先根据滑坡地表位移监测数据的特点对统计样本进行合理筛选.再通过降雨因子与滑坡发生的相关性分析以及对滑坡在降雨条件下位移变化情况的数值模拟,确定了适用于不同时间阶段的降雨统计变量.然后将考虑了滑坡规模特征的滑坡位移比（累计位移与滑坡纵长之比）作为变形指标,分时段统计滑坡地表位移监测数据与历史降雨信息,建立了日降雨数据与月位移数据的对应关系,得到了可用于确定降雨量阈值的位移比模型,并获得了云阳县蠕变型滑坡的五级预警分区.最后分别选用研究区滑坡险情实例、长年位移监测数据及极端降雨事件对模型预警效果进行检验.结果显示基于专业监测数据的位移比模型的滑坡降雨预警结果与实际情况相符,可为蠕变型滑坡的预警预报提供依据. 相似文献
20.
众所周知,库水位变化和降雨复合动力往往是水库型滑坡的变形和破坏主因。本文在系统分析水库型边坡位移、库水位及降雨变化规律基础上,提出与确定了降雨与库水动力转换系数k的计算方法,并通过转换系数k将降雨动力与库水动力这两种不同的水动力增载效应进行了有机耦合叠加,建立了复合水动力增载参数的计算方法。并将复合水动力变化量及其位移变化量作为动力增载及其响应参数,建立了水库型滑坡复合水动力增载位移响应比物理预测参数与模型。同时,运用该模型对白水河滑坡复合水动力作用下的稳定性演化规律进行了系统分析与评价,结果表明该滑坡复合水动力增载位移响应比的变化规律与其稳定性动态演化规律相吻合,表明复合水动力增载位移响应比参数是一种水库型滑坡有效的物理评价参数,可运用该物理评价参数与预测模型对该类滑坡稳定性进行分析与评价。 相似文献