共查询到20条相似文献，搜索用时 31 毫秒
1.
填方路堤变形失稳是西部山区工程建设的常见问题。重庆某高速公路边坡为典型的堆载条件下降雨诱发型滑坡,填方堆载后,填方边坡在连续降雨条件下,沿基岩之上的软弱面产生滑动破坏。定性分析认为,降雨在滑坡形成中起着关键作用,为了研究填方边坡在降雨条件下的变形破坏机制及孔隙水压力与变形之间的关系,采用物理模拟方法研究边坡变形失稳的全过程,分析孔隙水压力随降雨时间的变化规律及其与变形破坏的关系。研究结果表明：边坡后缘大方量堆载,改变了其应力条件,是滑坡产生的主要因素。场地施工改变了原有的地表水环境,连续强降雨致使大量下渗的雨水,不仅显著改变坡体应力条件,而且雨水沿着滑面运移软化滑带,是滑坡产生的重要诱发因素。孔隙水压力在坡体失稳过程中起着关键作用,填方体土碎屑、泥质含量大,下渗的雨水携带上部细小颗粒及滑带泥质成分至滑带附近,堵塞地下水消散通道,表现为坡体变形积累,孔隙水压力增加;边坡变形陡增,孔隙水压力降低。该滑坡破坏分为降雨下渗、滑带饱水软化、后缘产生裂缝、裂缝贯通-整体滑动4个阶段,为蠕滑-拉裂式滑坡。 相似文献
2.
Detection of water infiltration and deformation of unsaturated soils by elastic wave velocity 总被引：1，自引：1，他引：0
Intense rainfall is the most important landslide trigger. In many mountainous environments of the world, heavy rainfall has caused many landslides and slope failures in a matter of seconds without warning. Therefore, an early warning system can be an effective measure to reduce the damage caused by landslides and slope failures by facilitating the timely evacuation of people from landslide-prone areas. In this study, we propose an idea to correlate soil moisture changes and deformations in slope surface by means of elastic wave propagation in soil. Constant shear stress drained triaxial tests where water was infiltrated from the bottom of specimen until failure, and slope model tests under artificial rainfall were performed to investigate the response of elastic wave velocities during pre-failure phases of rainwater infiltration and deformation. Analysis of the results has established that the elastic wave velocity continuously decreases in response of moisture content and deformation, and there was a distinct surge in the decrease rate of wave velocity when failure was initiated. Possible mechanisms were interpreted based on the test results. It is proposed that a warning be issued at switch of wave velocity decrease rate. This approach can thus serve as the basis of an early warning system for landslides and slope failure considering both moisture content and deformation. 相似文献
3.
通过系统分析边坡工程地质条件及岩体结构,采用定性分析结合有限元模拟研究了边坡变形破坏模式,并采用块体理论及极限平衡法系统分析边坡局部及整体稳定性。结果表明,切向边坡的变形破坏模式可以分为两类:深层变形破坏为受层间软弱夹层空间展布特征控制的块体失稳,浅表层破坏为局部块体失稳及强风化强卸荷带岩体沿最大剪应力带的滑移-拉裂变形。稳定性分析结果认为边坡浅表层岩体稳定性差,但发生深层破坏的可能性较小。 相似文献
4.
水对斜坡作用包括地表水流动作用和地表水入渗作用,地表水流动作用,如水库、河流的岸坡破坏,由水动力侵蚀所引起。目前黄土中地表水入渗影响下的斜坡稳定性分析存在一些概念含糊的问题,如忽略了入渗过程的应力路径,只考虑其破坏时的应力状态,这会导致对其破机理和稳定性计算参数取值的误判,文章只针对该类问题进行辨析讨论。黄土中地表水的入渗一般有降雨和灌溉两种,伴随降雨入渗多引起斜坡浅层破坏;灌溉导致地下水位上升则引起深层滑移。地表水入渗对斜坡总应力改变不大,水致斜坡破坏主要是孔隙水压力上升,土体有效应力降低所致。非饱和黄土中的初始孔隙水压力为负值,降雨入渗后的浅层黄土仍处于非饱和状态,孔压最大升到0;灌溉会引起地下水位抬升,潜水位下为正的孔隙水压力。明确了孔压变化过程,就可以用有效强度评价边坡稳定性。同时,目前一些观点认为关于流动性黄土滑坡是静态引起,这颠倒了因果关系,是滑移引起了液化,而不是液化导致的滑移。 相似文献
5.
Analysis of time-varying rainfall infiltration induced landslide 总被引：5，自引：0，他引：5
Chen Chien-Yuan Chen Tien-Chien Yu Fan-Chieh Lin Sheng-Chi 《Environmental Geology》2005,48(4-5):466-479
A case study of rainstorm-induced landslide is modeled following the hourly rainfall time series from the stage of infiltration
caused by induced slope movement and soil saturated to excess pore pressures—Transient Rainfall Infiltration and Grid-based
Regional Slope-Stability Analysis (TRIGRS). The grid-based landslide stability analysis was conducted to model the increased
pore pressures and runoff in the study area under the specified rainfall conditions. The generated time variances of pore
pressures help determine landslide characteristics and mechanisms under rainfall conditions. Inputs of soil properties and
permeability parameters for landslide stability analysis in the study area were prepared by TRIGRS adopted for transient infiltration
analysis. Results of the analyses show that under heavy rainfall conditions, the infiltrated slope is unstable and the time
of debris masses movement initiated is correlated to the recorded time. In the initiated landslide, characteristics and effects
are considered and reflected in the numerical modeling under combinations of topography, land use, climatic and geological
conditions. Results reveal that there is a plane failure surface and a potential circular failure surface at the study site
besides the rock topple failures in the crest. A grid-based slope-stability analysis incorporated with the GIS spatial functions
is more advantageous than the traditional two-dimensional analysis for specified slope profiles to determine the whole behavior
of a slope. 相似文献
6.
降雨是导致斜坡破坏的主要原因。地下水位上升和在土中渗流引起土体应力状态的变化是导致斜坡在降雨过程中或降雨后变形与破坏的关键因素。填土斜坡的稳定性不仅取决于填土的强度,还与填土斜坡的排水条件密切相关。适当的排水条件不仅可以限制斜坡中地下水位上升的高度,而且可以及时消散因材料剪切收缩而生成的超孔隙水压力,防止土体液化,避免斜坡整体流动破坏。本文采用完全耦合有效应力分析程序和与状态相关的剪胀性砂土模型模拟地下水位上升过程中填土排水条件对压实填土斜坡稳定性的影响。完全耦合有效应力分析方法可以模拟孔隙水和土骨架间包括浮力和渗流在内的相互作用。分析结果表明斜坡排水条件是影响斜坡因地下水位上升而变形和破坏的重要因素,加固松散填土斜坡时必须设置适当的排水与泄水装置。 相似文献
7.
为研究间歇型降雨作用下缓倾堆积层斜坡的变形破坏特征,以樱桃沟滑坡为例,进行了降雨作用下斜坡变形破坏的物理模拟研究。试验结果表明：前期降雨作用下坡体变形特征表现为前缘滑移沉陷、中部滑移、后缘沉陷、坡体裂缝生成,且前缘裂缝扩张明显,后期降雨作用下坡脚区域首先发生滑塌,然后依次向后缘传递发生逐阶滑塌破坏;降雨入渗易在基岩面上储存,形成暂态地下水位、高孔隙水压力区域和坡向渗流场,基岩面附近土体饱水时间长,软化程度高,抗剪强度弱化显著,边坡易沿基覆界面土层发生滑坡;坡体滑动易发生在降雨间歇期,触发特征表现为雨后坡体暂态饱和区水分和坡表积水持续下渗,导致地下水位上升滞后于降雨,造成坡体内浮托力、渗透力和孔隙水压力增大,有效应力降低,诱发滑坡。 相似文献
8.
The 2007 Chuetsu Oki earthquake (MJMA = 6.6) triggered more than one hundred slope failures in the northwest part of Niigata prefecture, Japan. A reconnaissance
survey conducted by the authors revealed that although most of the failures were only a few meters deep, they still caused
significant damage to roads, railways, and houses. It was also found that a vast number of shallow slides were concentrated
along the coastal line of the Japan Sea, while only few, but relatively larger failures occurred in a mountainous part of
the study area, which is located in a considerable distance from the earthquake’s epicenter. This paper summarizes the reconnaissance
observations, describes the geologic characteristics of the area covered by landslides, provides characterization of major
types of the landslides, and examines the causes and mechanisms of typical failures. In addition, this paper seeks to investigate
the mechanism of the Ohzumi landslide, the largest slide triggered by the Chuetsu Oki earthquake. For this purpose, a comprehensive
analysis that included field investigation and laboratory testing of soils samples was performed. Results of field investigation
suggested that the failure plane of the Ohzumi landslide formed in a saturated layer of sandy soil near a boundary with bedrock.
Data from undrained cyclic loading triaxial compression tests indicated that the sandy material was highly susceptible to
generation of high excess pore-water pressures during earthquake loading. On the basis of the obtained results and the outcome
of seismic response and slope stability analyses, the authors posited an explanation on the mechanism of the Ohzumi landslide. 相似文献
9.
On August 27, 2014, a large-scale landslide occurred in Fuquan, Guizhou, China. This high-speed landslide caused considerable destruction; 23 people were killed, 22 were injured, and 77 houses were damaged. Field investigations, deformation monitoring, and numerical analyses have been performed to examine the characteristics and formation processes of this landslide. In the Xiaoba area, the slope showed a two-layered structure with a hard upper layer and a soft lower layer. Dolomite of the Dengying Formation in the slope front formed a locked segment controlling slope stability. Based on deformation and failure characteristics, the landslide is divided into sliding source area A and accumulation area B. The landslide is also divided into the following stages: bedding slip, tension cracking at the slope scarp, and the appearance of the locked section at the slope toe. Numerical calculations show that excavation led to maximum shear strain concentration along the interface of siltstone and slate in the middle of the slope, which became a potential sliding surface. Stress concentration and distribution of the plastic zone of the locked segment of the Dengying Formation dolomite occurred in the slope toe. Continuous rainfall caused the groundwater level to rise in the Xiaoba slope. The unfavorable geological structure was a determinant factor, and the combined effects of excavation and continuous rainfall were triggering factors that induced the landslide. The geomechanical mode for the Xiaoba landslide is sliding tension–shear failure. 相似文献
10.
Following a heavy rainstorm on 29 June 1999, hundreds of slope failures occurred in granitic mountains in Hiroshima Prefecture, Japan. Among these events, a highly mobile landslide (termed the Kameyama landslide in this paper), which occurred in Kameyama area of Hiroshima city, was the most catastrophic, and was investigated in detail. The displaced soil mass from the source area of this landslide traveled about 300 m and deposited a volume more than 10 times as great as that in the source area. The landslide originated in and traversed a valley-shaped concave slope covered by pre-existing colluvial debris deposits. In addition, a spring was visible in the source area and very shallow ground water was observed in an observation pit dug in the source area. Thus, it is inferred that the ground-water table rose quickly during the rainfall, and that this rise triggered the slope failure in the source area. Based on a field survey along the landslide cross section, a possible explanation for the mechanism of the landslide was obtained: the displaced soil mass from the source area impacted the debris deposit in the path of the landslide, thus triggering liquefaction failure of the saturated part of debris. The original landslide and the liquefied debris then moved downslope as a single mass. To examine this assumption, ring-shear tests were performed on samples taken from the source area. Undrained ring-shear tests on the saturated samples showed that the sample is highly liquefiable, and liquefaction failure could have been triggered in the debris deposits by a very small impact from the displaced soil mass of the initial failure. In addition, laboratory tests simulating the impacts on the debris deposits at natural water content, i.e., unsaturated (at the survey time, 2 days after the failure) showed that although shear failure could be caused by the assumed impact force, the displaced soils stopped after a few centimeters displacement, indicating that existence of a saturated zone in debris deposits is prerequisite for this kind of failure. 相似文献
11.
The Kualiangzi landslide was triggered by heavy rainfalls in the “red beds” area of Sichuan Basin in southwestern China. Differing from other bedrock landslides, the movement of the Kualiangzi landslide was controlled by the subvertical cracks and a subhorizontal bedding plane (dip angle < 10°). The ingress of rainwater in the cracks formed a unique groundwater environment in the slope. Field measurement for rainfall, groundwater movement, and slope displacement has been made for the Kualiangzi landslide since 2013. The field monitoring system consists of two rainfall gauges, seven piezometers, five water-level gauges, and two GPS data loggers. The equipments are embedded near a longitudinal section of the landslide, where severe deformation has been observed in the past 3 years. The groundwater responses to four heavy rainfall events were analyzed between June 16 and July 24 in 2013 coincided with the flood season in Sichuan. Results showed that both of the water level and the pore-water pressure increased after each rainfall event with delay in the response time with respect to the precipitation. The maximum time lag reached 35 h occurred in a heavy rainfall event with cumulative precipitation of 127 mm; such lag effect was significantly weakened in the subsequent heavy rainfall events. In each presented rainfall event, longer infiltration period in the bedrock in the upper slope increased the response time of groundwater, compared to that of in the gravels in the lower slope. A translational landslide conceptual model was built for the Kualiangzi landslide, and the time lag was attributed to the gradual formation of the uplift pressure on the slip surface and the softening of soils at the slip surface. Another important observation is the effect on the slope movement which was caused by the water level (H w) in the transverse tension trough developed at the rear edge of the landslide. Significant negative correlation was found for H w and the slope stability factor (F s), in particular for the last two heavy rainfall events, of which the drastic increase of water level caused significant deterioration in the slope stability. The rapid drop (Δ?=?22.5 kPa) of pore-water pressure in the deep bedrock within 1 h and the large increase (Δ?=?87.3 mm) of surficial displacement were both monitored in the same period. In the end, a four-level early warning system is established through utilizing H w and the displacement rate D r as the warning indicators. When the large deformation occurred in flood season, the habitants at the leading edge of the landslide can be evacuated in time. 相似文献
12.
Cheng Qiu Tetsuro Esaki Mowen Xie Yasuhiro Mitani Chunxiang Wang 《Environmental Geology》2007,52(8):1569-1579
A shallow landslide triggered by rainfall can be forecast in real-time by modeling the relationship between rainfall infiltration
and decrease of slope stability. This paper describes a promising approach that combines an improved three-dimensional slope
stability model with an approximate method based on the Green and Ampt model, to estimate the time–space distribution of shallow
landslide hazards. Once a forecast of rainfall intensity and slope stability-related data, e.g., terrain and geology data,
are acquired, this approach is shown to have the ability to estimate the variation of slope stability of a wide natural area
during rainfall and to identify the location of potential failure surfaces. The effectiveness of the estimation procedures
described has been tested by comparison with a one-dimensional method and by application to a landslide-prone area in Japan. 相似文献
13.
14.
Thanh Son Nguyen Suched Likitlersuang Hiroyasu Ohtsu Takafumi Kitaoka 《Arabian Journal of Geosciences》2017,10(16):369
Rainfall-induced landslides frequently occur in humid temperate regions worldwide. Research activity in understanding the mechanism of rainfall-induced landslides has recently focused on the probability of slope failure involving non-homogeneous soil profiles. This paper presents probabilistic analyses to assess the stability of unsaturated soil slope under rainfall. The influence of the spatial variability of shear strength parameters on the probability of rainfall-induced slope failure is conducted by means of a series of seepage and stability analyses of an infinite slope based on random fields. A case study of shallow failure located on sandstone slopes in Japan is used to verify the analysis framework. The results confirm that a probabilistic analysis can be efficiently used to qualify various locations of failure surface caused by spatial variability of soil shear strength for a shallow infinite slope failure due to rainfall. 相似文献
15.
Geotechnical assessments of the stability of slopes at the Cakmakkaya and Damar open pit mines (Turkey): a case study 总被引：2，自引：2，他引：0
Fehmi Arikan Fatih Yoleri Sureyya Sezer Dincer Caglan Bengu Biliyul 《Environmental Earth Sciences》2010,61(4):741-755
The on-site observations, monitoring data, and results of back analyses of failures showed that large-scale failures occurred
along both the interconnected sliding surfaces, consisting of (a) discontinuities in the dacites and the contact zone and
(b) the circular surfaces through the weathered soil-like dacites at the Cakmakkaya and Damar open pit mines. Surface water
infiltration through the weathered soil-like material after a short duration of rainfall contributed to the circular-shaped
failures. After a heavy rainy period, an increase in the groundwater table above the contact zone played a major role in the
initiation of bi-planar wedge failures. In addition, the stability of the slopes is likely to have been controlled by the
orientation of this zone. The results of back analyses indicated that the shear strengths of the soil-like materials in the
weathered dacites and the contact zone had reduced to their residual values at the time of initial sliding. The flattening
of the slope angles with an effective surface drainage and long-term monitoring of the groundwater level is proposed as the
most suitable remedial measure. 相似文献
16.
Harianto Rahardjo Mărgărit-Mircea Nistor Nurly Gofar Alfrendo Satyanaga Qin Xiaosheng Sabrina Ip Chui Yee 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2020,14(3):177-191
ABSTRACT This paper presents the spatial distribution, variation and trend of 5-day antecedent rainfall in Singapore based on rainfall data from 22 meteorological stations. The effect of climate was analyzed by dividing the study period into three decades i.e. Decade 1: 1982–1991, Decade 2: 1992–2001 and Decade 3: 2002–2011. Kriging interpolation was used for rainfall mapping. The results show that spatial distribution of 5-day antecedent rainfall does not coincide with that of the annual rainfall. The maximum annual rainfall occurred in the northwestern side of Singapore. On the other hand, the maximum 5-day antecedent rainfall occurred in the north and northeastern sides. The results of this study suggest that the climate change has increased the amount of 5-day antecedent rainfall quite significantly, i.e. from 420.5 (1987) to 592.9 mm (2006), thus affecting the vulnerability of the area with respect to rainfall-induced slope failure. The analyses also showed that most of slope failures were located in the north and northeast of Singapore between December and earlier March. More slope failures were observed in Decade 3 as compared to Decades 1 and 2. In other words, the analysis confirmed that 5-day antecedent rainfall had affected the slope stability in Singapore. 相似文献
17.
The common slope stability analysis is incapable of accurately forecasting shallow slides where suction pressures play a critical role. This realization is used for elaborate stability analyses which include soil suction to better predict rainfall-induced slides at railway embankment at Malda where three known cases of slope failures and train derailments occurred after heavy rainfall. The relationship between the soil–water content and the matric suction is established for the embankment soil. It is then used in the coupled analyses of seepage and slope stability to estimate performances of the embankment at different intensity and duration of rainfall. The numerical simulations are performed with the FE code Geo-Studio. The numerical results show significant reduction in the factor of safety of the railway embankment with the increase in the intensity and duration of rainfall. The effectiveness of the proposed mitigation measures including placement of 2 m-wide free draining rockfill across the slopes and drilling 5-m-long sheet pile wall at the toe of the embankment is studied numerically. The study confirms that the proposed mitigation measures effectively increase the factor of safety of the embankment and stabilizing it even in case of a heavy rainfall of 25 mm/h over 12 h. 相似文献
18.
R. K. Dubey J. A. Dar Gyan Prakash Satyam 《Journal of the Geological Society of India》2018,91(6):704-710
Slope stability has been identified as a major obstacle to construction in the rapidly developing countries of Indonesia and Malaysia. In these countries, slope failure has been identified as one of the most commonly occurring natural disasters, leading to financial losses and deaths. Slope failure is often related to prolonged rainfall events where rainfall infiltration increases pore water pressure, reducing soil strength. This failure mechanism will accelerate with the existence of cracks, which are usually caused by differential settling, drying and shrinking of soil, and associated construction activities, among other causes. The existence of cracks on slopes usually provides an easy pathway for rainfall infiltration into soil, allowing rain to infiltrate to deeper layers than in the absence of cracks. The moisture content in deep layers is therefore higher in cracked slopes than in slopes without cracks. To address this issue, we investigated the effects of cracks on slope stability when subjected to rainfall. The influence of crack location, depth, size, and direction on pore water pressure distribution and slope stability was studied by imposing different rainfall intensities. Analysis of seepage and stability were conducted using the GEO STUDIO 2007 softwares SEEP/W and SLOPE/W. Results suggested that pore water pressure and slope stability were influenced by the existence of cracks. Analysis showed that slope factors of safety decreased sharply when cracks were located adjacent to the slope crest, as compared to when cracks were located in the middle of the slope. Furthermore, slope factors of safety decreased with increasing crack depth. Pore water pressure and slope factors of safety decreased further when slopes were subjected to small rainfall intensities for long periods, as compared to when slopes were subjected to high rainfall intensities for short periods. The present study shows that study of cracks should be an integral part of the slope stability analysis. 相似文献
19.
A large landslide occurred at Maierato (Vibo Valencia District), Southern Italy, on 15 February 2010, when rapid failure was produced after several days of preliminary movements. The landslide can be classified as a rotational slide with flowing of the mass. It occurred within a larger deep-seated gravitational movement area and was preconditioned for failure by the intrinsic geological weakness of the area. Actually, the in situ survey showed the presence of several ancient movement surfaces all around the urban area. The landslide-triggering factor was the increase in the groundwater flow, consequent to a period of heavy and prolonged rainfall. The aim of the paper is to explain the mechanism of occurrence of the February 2010 composite landslide, in order to assess the landslide hydrogeological susceptibility in the whole urban area of Maierato. For this reason, the present paper deals with: (1) identification of the landslide mechanism and triggering factors (2) slope stability back-analysis using a finite-difference-based shear strength reduction method, and (3) 3D groundwater flow modelling extended to the whole urban area both in pre- and post-failure conditions. The results show that the February 2010 composite landslide was triggered by a water table increase of about 15 m uphill the landslide scarp. This hydrogeological condition could be reached after the period of heavy and prolonged rainfall preceding the landslide event. Finally, based on the groundwater modelling in post-failure condition, a landslide hydrogeological susceptibility map was drawn for the all urban area of Maierato, showing the presence of extended areas exposed to hazard. 相似文献
20.
浅层滑坡在我国广泛分布,但在区域范围内分布规律性较差,且具有突发性、隐蔽性和破坏性强等特点。湘西武陵山区地质条件复杂、降雨丰沛、人类工程活动强烈,突发性地质灾害频发,尤以降雨诱发的浅层滑坡为主。文章以湘西地区慈利县陈溪峪滑坡为例,开展了降雨量、基质吸力、地下水位和地表变形等的监测;结合滑坡的现场调查及监测成果,分析滑坡的形成条件和变形机理;在此基础上,考虑基质吸力对边坡稳定性的贡献,将强度折减有限元法推广到非饱和土边坡,计算得到了不同降雨工况下滑坡稳定性。结果表明:当强降雨降落到滑坡体上时,坡内基质吸力值均迅速减小,直至一定值后（9.5 kPa左右）不再变化;坡内地下水位受季节性降雨影响显著,短时强降雨引起地下水变化幅度不如长时间降雨对地下水位造成的影响大;陈溪峪滑坡的地质力学成因为蠕滑推移式土质滑坡,运动形式为沿基覆界面的浅层滑坡;短时强降雨是诱发滑坡变形的最关键因素。陈溪峪滑坡在持续降雨条件下的降雨量预警值约为280 mm,在短时强降雨条件下的降雨强度预警值约为240 mm/d。 相似文献