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1.
In September 1979, rain-induced complex landslides occurred in two separate localities along the slopes of the Akovolwo Mountains near Jato-Aka in the Kwande Local Government area of Benue State, Nigeria.The two movements developed on bedrock slopes covered by a veneer of colluvium and (or) residuum no more than 1.5 to 2m deep. Each started as a slump and graduated into a debris flow. The slump, extending downhill a short distance away from the head scarp, had been reconstituted into a debris flow as the initial movement (sliding movement) of the soil mass caused remoulding of the saturated moving mass into viscous debris-laden mud. The resulting mass moved partly along a pre-existing mountain stream channel and partly along a fresh channel it cleared in the savanna forest. At the break of slope, the mass of boulders was dumped and a trail of smaller fragments littered the channels towards the Katsina-Ala River. 相似文献
2.
Girish Ch. Kothyari P. D. Pant Khayingshing Luirei 《Journal of the Geological Society of India》2012,80(1):101-110
Main Boundary Thrust (MBT) zone is constituted of some of the landslide prone areas in southeastern part of Kumaun Sub-Himalaya. Role of landslides as natural hazard and hill slope modifying agent is well documented from various part of Himalayan region and southern hills of Kumaun particularly in the MBT zone, which are susceptible to various type of mass movement. The rocks making up the slopes has been put to a number of brittle deformation phases during the movement along the MBT, and are traversed by number of joint sets. In the open slope these intersecting joint sets forms wedges and are the most favorable site for initiation of rockfalls and other types of landslides. Landslides are taking place primarily due to high angle slopes, formation of structural wedges along the free steep slopes, sheared nature of the rocks due to proximity to the MBT and neotectonic activities along the MBT and other transverse faults. Wedge failure is a common type of landslides in rock slopes characterized by multiple joints and acts as sliding planes for the failed blocks. Field observations and wedge failure analysis indicates most of the landslides taking place in MBT zone of Kumaun Sub-Himalaya are joint controlled. Safety Factor analysis suggests MBT zone of Kumaun Sub-Himalayan region is prone to landslides and related mass movements. This zone is also neotectonically active as indicated by various geomorphic signatures such as structurally controlled drainage pattern, offsetting of fan by MBT and formation of number of small lakes. 相似文献
3.
S.W. Grab S.C. Mills 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(1):179-186
Several high south-facing slopes in the southern Drakensberg were glaciated during the Late Quaternary, yet little is known about the slope geomorphic history on equally high slopes that appear not to have been glaciated. To this end, we examine evidence for Late Quaternary slope dynamics in a high alpine valley of eastern Lesotho, with particular attention given to palaeo-environmental signatures offered by deep colluvial mantles along the flanks of the Sehonghong River and pronival ramparts along the upper southerly-facing slopes of the adjoining Thabana-Ntlenyana. Sedimentary exposures were mapped and sampled for clast fabric, clast shape, organic matter content, granulometry and 14C age determination. Similarly, a pronival rampart was mapped and clast size, shape and fabric determined for various micro-topographic settings. A palaeosol beneath the rampart was also Radiocarbon dated. Findings suggest that the deep and extensive debris mantles on lower south-facing slopes are a product of prolonged colluviation, whilst the more stratified sequences on north-facing slopes indicate greater slope geomorphic-process variability over time. Radiocarbon ages suggest sediment accumulation along the north-facing exposure from at least ∼43 ka. It is proposed that snowcreep and snowpush on high (>3400 m a.s.l.) southeast-facing slopes during a relatively cold, yet moist period at ∼AD 300-1000 initiated boulder movement to form the pronival ramparts. 相似文献
4.
Extensive deformations of mountain slopes occur in crystalline intrusive rocks in the southern Coast Mountains of British Columbia. Typical morphological evidence of slope movement includes extensive systems of tension cracks, grabens, and antislope scarps (collectively referred to here as linears). These landforms involve displacements along penetrative joints observed in surface exposures. Kinematic tests on rock-structural data indicate that the observed patterns of linears are generally consistent with the feasible gravitational movements along the dominant discontinuities. Most sites indicate sliding as the most likely initial mode of movement, followed by or accompanied by toppling and toppling-induced sliding movements, and do not support the view that linears are the traces of active faults. 相似文献
5.
This paper presents a case study of the analysis and design of slopes for the portal of an underground crude oil storage cavern site. The site selected for the slope study is characterized by residual soils and granitic rock formations, located in the southwestern part of India. It is observed that in tropical residual soils, most hillslope failures are caused by rainfall and thus it is important to consider hydrological conditions when attempting to analyze the stability of slopes in such material. Combinations of shallow slopes with lower overburden and high steep hillslope with large overburden were considered in the present study along with varying combinations of lateritic soils and weathered rock formations. The paper discusses the various investigations carried out to define the geotechnical properties of lateritic soil and weathered rock, followed by numerical modelling and remedial measures adopted to ensure the stability of slopes during design and construction phase. Since analysis and design procedures for such residual soils are not well established, comprehensive geological and geotechnical investigations were carried out prior to numerical model development for carrying out finite element studies in order to ascertain long term stability of slopes under differing ground conditions. The results of the stability analysis indicated that slope under existing condition were potentially unstable under rainy conditions and specific supporting measures were planned to ensure stability. Several alternatives were examined for improving the stability of slope taking into consideration existing facilities, space available for mobilization of equipments and environmental conditions in reference to specific project requirements. The convergence pattern obtained from geotechnical monitoring using optical targets along the slopes did not showed any alarming movement for over a year. 相似文献
6.
Shales of the Lower Ecca stage of the Late Palaeozoic Series are actively degrading in the particular topography and climate of Natal. The failure of a large road embankment near Pietermaritzburg and the subsequent failure of the adjacent natural slope were caused by movement along existing shear zones in the underlying colluvium. Other cases of instability in both natural slopes and engineering earthworks are known, in the Pietermaritzburg and Durban areas and elsewhere in Natal. These failures in various types of slope in different parts of Natal suggest an inherent instability in colluvial and residual soil derived from shale of the Lower Ecca stage. 相似文献
7.
Brahim Meziani Djamel Machane Abderrahmane Bendaoud Ghani Cheikh Lounis El-Hadi Oubaiche Souhila Chabane Rabah Bensalem Hakim Moulouel 《Arabian Journal of Geosciences》2017,10(5):117
The Ain Turck (Bouira) landslide, in north-center Algeria, is one of the numerous instabilities recorded along the Lakhdaria-Bouira section of the 1200-km-long east-west Algerian highway. The locality of Ain Turck is known for its unstable slopes characterized by a very rough morphology with steep slopes (20 to 25%). This slide threatens the inhabitants of the Ibournanen village, located down the unstable slope, where parts of some houses have fallen into ruin, while others are cracked. It is characterized by an active movement extending over a more or less important slope, of the order of a hundred meters. The land mobilized by this movement corresponds to the layer of shale clays and clays overlaid by a backfill, placed there following the east-west highway works. Geological, geomorphologic, and geotechnical analysis allows determining the soil instability probably related to earthworks during the construction of the highway section a few years earlier, followed by a particularly rainy season in 2012. Acquisitions of ambient seismic noise and H/V ratio processing, as well as the acquisition of an electrical resistivity profile at the instability site, have reinforced our preliminary interpretations of depth and geometry of the sliding surface. 相似文献
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The presence of a weak interlayer has usually an adverse effect on the slope stability. However, the rotational failure mechanism in the conventional upper bound limit analysis cannot rationally describe the sliding of the failure mass along the weak interlayer. Therefore, a new failure mechanism was proposed in this study to evaluate the stability of slopes with weak interlayers using the upper bound limit analysis and the associated factor of safety was determined by the shear strength reduction technique. The new failure mechanism is comprised of rigid blocks undergoing rotational or translational movements, instead of the rotational movement in the conventional failure mechanism. It has also been extended to the stability analysis of slopes in presence of stabilizing piles and pore water pressures. Case studies were carried out on actual slopes with weak interlayers. The proposed rotational–translational failure mechanism was verified by the shear strength reduction finite element method (SSRFEM). Comparisons demonstrate the reliability of limit analysis method with the proposed rotational–translational failure mechanism for slopes with weak interlayers and therefore it can be used as a simple evaluation method for the engineering design. 相似文献
10.
Baofeng Di Constantine A. Stamatopoulos Miranda Dandoulaki Eleni Stavrogiannopoulou Meng Zhang Persefoni Bampina 《Natural Hazards》2017,85(2):903-927
The work considers critical slopes located at regions with high danger and proposes a method which approximately predicts the risk of earthquake-induced excessive movement of these slopes, in the case where relevant soil strength data along their slip surface do not exist. The method utilizes (1) simplified constitutive equations predicting soil response along slip surfaces and (2) a multi-block sliding system model, both recently proposed. It involves the following steps: (a) collect relevant topographic information and laboratory test results of past landslides at the region of interest, (b) (i) analyze the relevant laboratory tests to estimate the soil constitutive parameters and (ii) estimate the mobilized residual soil strength by back analysis of relevant past landslides, (c) select constitutive model parameters for future applications at the region based on step (b) and validate them based on analysis of the triggering of the past landslides and (d) apply the selected constitutive model parameters in critical slopes in the region under consideration to predict not only whether triggering occurs, but also the post-triggering slide deformation. The paper, after describing in detail the proposed method, applies it at the Wenchuan region, where the 12th May 2008 earthquake triggered many landslides. During the application, four ring shear test results and twelve landslides of the 12th May 2008 earthquake were considered. The application was successful and the following were observed: (i) in the back analyses, the multi-block model predicted reasonably well the final configuration of all slides, (ii) apart from two significantly larger back-estimated values of the residual soil strength, small scatter existed in the other back-estimated values and (iii) the selected model parameters were duly validated under step (c). Furthermore, as the back-estimated friction angle of most landslides was less than 18°, and the materials along the slip surface have a Liquid Limit value less than 25 %, it is inferred that some, or all of the slip surface during these slides, was sheared in an undrained manner. 相似文献
11.
Evaluating cut slope failure by numerical analysis—a case study 总被引：3，自引：3，他引：0
Slope failure is very common phenomenon in hilly regions, especially in young techno active mountainous like Himalayas. It
is hazardous because of the accompanying progressive movement of the slope-forming material. In order to minimize the landslide
effects, slope failure analysis and stabilization requires in depth understanding of the process that governs the behavior
of the slope. The present article mainly deals with the analysis of the stability of road cut slopes of Rudraprayag Area,
Uttarakhand, India. The area experiences local as well as regional slides every year. Extensive field study was carried out
along the road cut slopes. Laboratory experiments were conducted to determine the various Physio-mechanical properties of
rock mass. These properties have been used as input parameters for the numerical simulation of slope using FLAC3D (Fast Lagrangian
Analysis of Continua) including geological discontinuities. The computed deformations and the stress distribution along the
failure surface are compared with the field observations. The study indicates that the overall slope is unstable except at
the location E where slope is critically stable. The effects of instability have been thoroughly considered and remedial measures
have been recommended. 相似文献
12.
地震与非地震诱发滑坡的运动特征对比研究 总被引：1，自引：1，他引：0
针对不同诱发机制的滑坡运动特征差异,以滑坡的总斜率和阻止系数为评价指标,分析滑坡的总斜率、阻止系数与滑坡规模、总能量的关系,对比研究了地震和非地震滑坡的总斜率、地形阻止系数的特征。研究结果表明：地震与非地震滑坡的规模越大在运动过程中受到的阻止作用越小;地震滑坡和非地震滑坡的总斜率都随滑坡规模和总能量增加而减小,但地震滑坡减小的速率大于非地震滑坡;地震滑坡的平均阻止系数约为0.4～0.5,而非地震滑坡的平均阻止系数约为同规模地震滑坡的40%～50%。因此,滑坡的运动特征不仅受滑坡规模及总能量控制,还显著地受滑坡的诱发机制和地形阻止等因素的影响。 相似文献
13.
S. Sreekumar 《Journal of the Geological Society of India》2009,73(6):813-820
The occurrences of slope failures are frequent in Idukki district of Kerala state particularly along the road cuttings and
hill slopes causing disruption in traffic, loss of lives and property. This demands a critical evaluation of stability of
slopes along the hill roads. This paper deals with stability analysis of a typical hard rock profile at Chuzhappu and a lateritic
profile at Kumili along the road connecting Kottayam and Kumili. A large number of factors have been examined and studied;
the orientation of discontinuities has been identified as one of the major inherent factors influencing slope instability
along Chuzhappu hard rock profile. These have been analysed carefully using stereographic/equal area projection technique
in order to determine the vulnerability to slope failure and to understand the type of rock slide that can occur in this profile.
The buoyant force of water acting along the discontinuities after heavy rain storm further aids the down slope movement. As
the laterite slope is mostly homogeneous, Bishops method and Swedish method were adopted for stability analysis of laterite
slope at Kumili. The study also examines the efficacy and applicability of the different methods employed in soil mechanics
to assess the stability of laterite slope.The results obtained by this method are compared by actual field conditions. The
stability assessment indicates that two sectors at Chuzhappu and one sector at Kumili profile are at the geo-technical threshold
of failure, when piezometric head rises during rainstorm. The study indicates that these methods are highly useful in determining
the Factor of Safety in profiles with similar geological setting. 相似文献
14.
Chen Shanxiong* School of Civil Engineering Mechanics Huazhong University of Science Technology Wuhan China Institute of Rock Soil Mechanics Chinese Academy of Sciences Wuhan China Yu Song Liu Zhiguo Xu Haibin Institute of Rock Soil Mechanics Chinese Academy of Sciences Wuhan China 《中国地质大学学报(英文版)》2005,16(4)
INTRODUCTION Theinfiltrationandevaporationofwaterinasoil slopeareofparamountimportanceindetermining slopestability.Previousengineeringcasesandstud ieshaveshownthatrainwaterisoftenamajorfactor intheslopefailureofexpansivesoils.Expansivesoils intropicalandsubtropicalzonesareoftenunsaturat ed,andsoilslopesareinastablestateinnormalcli mateconditionsbecauseofthehighsuctionandshear strengthofthesoilmass.However,oncepermeation happensrainwaterwillinfiltrateintothesoilmasswhichleadstoanincreasein… 相似文献
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16.
Satish Kumar Kishor Kumar N. N. Dogra 《Journal of the Geological Society of India》2017,89(4):407-412
Rock slopes require geo-engineering evaluation to assess the instability of critical slopes leading to landslides particularly in Himalayan terrain where rocks are highly jointed, fractured and weathering prone. Interplay of discontinuities in the rocks coupled with other parameters is one of the prime causes of failure of slopes. Engineering rock mass classification, such as, rock mass rating (RMR) and slope mass rating (SMR) along with geological strength index (GSI) have widely been used for stability assessment of rock slopes above tunnel portals, and these classifications are employed here for assessment of stability of slopes of critical nature along Rampur-Powari highway in Himachal Pradesh. In the present study, out of 154 numbers of slopes, a total of 29 have been selected for assessment of their criticality by employing RMR, SMR and GSI. 相似文献
17.
通过模型实验,探讨了松散土坡3种不同结构特征条件下(均匀坡体(坡体物料均匀混合)、平行坡体(土层成层且层面与滑面平行)和斜交坡体(土层成层且层面与滑面斜交))形成滑坡堰塞体的动力过程和堆积特征,通过分区域取样及三维扫描技术研究了堰塞体的物质分布规律与形态特征。研究结果表明:堰塞体堆积特征与坡体特征存在紧密联系,堰塞体纵向(沿主沟道方向)和横向(沿滑坡运动方向)上的物质分布与坡体纵向和横向的物质分布特征基本对应;在垂向(表层到底部)上,由于不同坡体条件下滑坡的动力过程和机理不同,从而导致堰塞体堆积特征存在一定区别。均匀坡体和平行坡体呈整体启动模式,运动过程中物料间存在垂向渗透和交换作用,导致堰塞体物质在垂向上呈明显的上粗下细反粒序分布特征,堰塞体横剖面多呈平坦型和倾斜型。斜交坡体呈分层启动模式,运动堆积过程中保持原有层序,粗、细颗粒先后启动条件下颗粒间存在推挤、爬升和水平渗透作用,使得堰塞体更加密实且垂向上也呈现反粒序分布特征,横剖面多呈起伏型。本研究为滑坡堰塞体稳定性快速评估和复原滑坡初始状态提供依据。 相似文献
18.
鄂西北山区降雨型边坡失稳模式和评价方法 总被引：2，自引：1，他引：1
2003年6月的一次连续降雨诱发了鄂西北山区郧漫公路沿线多处边坡失稳。根据边坡岩土体的组成和结构特征,总结出了5种典型的暴雨型边坡失稳模式:浅层堆积体滑移、含软弱面顺层滑移、切层边坡水压劈裂破坏、碎裂岩似弧形追踪破坏和块裂岩楔体滑移。根据边坡破坏特点和降雨作用形式提出了相应的评价方法,认为浅层堆积体在暴雨下含水量,即85%~100%液限含水量时易发生滑移,通过平面无限斜坡评价法计算边坡稳定性;含软弱面顺层边坡及块裂楔形体均为剪切滑移失稳,采用简化的刚体极限平衡法计算其稳定性;切层边坡中陡倾裂缝经历了卸荷张开－水压开裂－贯通破坏的过程,通过Ⅰ型裂缝扩展判据评价边坡稳定性;碎裂岩边坡发生类似弧形滑移的追踪破坏,采用连续介质圆弧法计算边坡稳定性。 相似文献
19.
2013年1月11日云南省镇雄县发生特大山体滑坡灾害,造成赵家沟村民小组46人遇难和严重经济损失。基于数次滑坡现场调查和勘查所获得的基础数据,本文对滑坡特征及变形失稳机理进行了较系统的研究。（1）滑坡发育在崩坡积体中,坡体自后缘向前缘具有黏粒含量、密实度增加而孔隙度、透水性减小的特点;（2）滑坡后缘为飞仙关组强风化粉砂岩与崩坡积体的接触界面,滑动带为崩坡积体内含砾粉质黏土坡积层;（3）滑坡发生前,坡体后缘已发育张拉裂缝,前缘已发生小型鼓胀破坏,属典型蠕滑-拉裂变形破坏模式;（4）滑坡具有分块先后滑动特点,左、右及后缘边界坡体在主滑体后发生滑动,滑移过程中也存在分区现象;（5）滑带土为低液限含砾黏性土,呈液化流塑状态,抗剪强度低;（6）启程高速是斜坡应变能长期积累、瞬间释放的结果,滑程高速与滑坡体冲击液化有关,部分滑体存在临空飞行现象。建议加强滑源区两侧裂缝的变形监测和乌蒙山区类似坡体的灾害预警。 相似文献
20.
Abhishek Kumar Chaurasia H. K. Pandey H. C. Nainwal Jitendra Singh S. K. Tiwari 《Journal of the Geological Society of India》2017,89(6):689-696
The rock mass rating (RMR) and slope mass rating (SMR) has been carried out to classify the slope in terms of slope instability. To understand the RMR and SMR various geostructural, geomorphologic and hydrological parameters of the slopes were measured and analyzed. 32 rock slopes/rock cum debris slopes were identified in the study area. The present RMR and SMR study is an outcome of extensive field study along a stretch of about 10 km on road leading from Srinagar to Pauriarea along Alaknanda valley. The technique followed incorporates the relation between discontinuities and slope along with rock mass rating (RMR) and slope mass rating (SMR). The analysis of the 32 studied slopes shows that in the Gangadarshan area out of six rock slope facets, two falls in class II (stable) and four in class IV (unstable). It is significant to note that the slope facets coming under class IV are comprised of active landslide portions. While the slopes under class II show minor failure or old landslide debris. 相似文献