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1.
An earthquake of M w 9.0 struck the Pacific coast in northeast Japan on March 11, 2011 and was followed by a hugely damaging tsunami along 500 km
of the Japanese coastline. An inland aftershock of M. 7.0 occurred on April 11; during which, surface fault ruptures appeared
on land. A large variety of landslide disasters resulted from these earthquakes in various parts of northeastern Honshu, Japan.
The full extent of the landslides is still being determined. This brief report introduces some of the landslide phenomena
so far investigated by the Japanese Landslide Society. These are (1) failure of a water reservoir embankment dam in Sukagawa,
Fukushima prefecture, (2) landslides and surface seismic fault rupture from the April 11 aftershock in Iwaki, Fukushima, (3)
a concentration of surface failures at Matsushima Bay in Miyagi prefecture, and (4) small landslides on modified slopes in
residential areas around Sendai city. 相似文献
2.
The stability of both natural and cut slopes in mountainous areas is a great challenge to highway constructions and operations. This paper presents a successful case study of stability analyses and protection treatments for high-steep cut soil slopes in an ancient landslide zone which was located at Km12+700 to Km15+000 along the Tehran?CChalus highway. This report has three parts. First, geotechnical investigations of in situ direct shear test, SPT tests and laboratory tests were implemented to get the subsurface profiles and the mechanical properties of the soil mass. Second, finite difference analysis was carried out to evaluate the stability of both the natural and cut slopes. Minimum safety factors and potential failure modes of cut slopes were obtained under both static and dynamic conditions. These results indicated that the ancient landslide could not be reactivated under the present climatic and morphological conditions, but there were some potential shallow failures in some cut soil slopes (failure actually occurred during excavation). Protection treatments and reinforcements were thus necessary. Third, the stability of the cut slopes was re-assessed by simplified Bishop limit equilibrium analysis (using Slide 5.0). Some potential failure zones were designed to be protected by back-anchored concrete retaining wall at the slope toe, rock bolts and frame beams on the slope face and planting grass on the slope face. Numerical analysis indicated that these protection measures could stabilize this remedial slope. These practical experiences may be of benefit for similar highway construction projects. 相似文献
3.
人工高切坡开挖常常导致边坡失稳破坏,甚至诱发滑坡发生,为此提出了高切坡超前锚杆支护的设计新方法。超前支护锚杆能够约束边坡变形和开挖卸荷带的发展,维持边坡的稳定,对超前支护锚杆的作用机制问题进行了研究,阐述了超前支护锚杆的荷载传递特性,为超前支护锚杆设计提供了理论依据。 相似文献
4.
On the basis of geological and geomorphological surveys, landslide phenomena are analysed on a slope along a stretch of the Adriatic coast, near Petacciato (Molise, Italy). Locally, a blue clay sequence of Pleistocene outcrops, stratified with silty-sandy layers; bedding dips 3–8°NE and the slope has a similar attitude. This sequence evolves upwards to sands and conglomerates, with thickness of up to 40 m, on which the built-up area is located. Several episodes of landslide reactivation occurred in the past century, involving the zone between the built-up area and the sea, along a coastal slope of over 2000 m long and 200 m high. Important roads and railway lines have been heavily damaged as well as the town itself. The typology of the movement is a rotational–translational slide; the displacement reaches tens of centimetres at each reactivation episode along the entire coastal slope, extending well beyond the shore line. Detailed studies already exists, but different mechanism failures have been proposed to explain the landslide phenomena. In this study, a new failure mechanism is proposed, (sudden spreading of Terzaghi, K., Peck, R.B., 1948. Soil Mechanics in Engineering Practice. Wiley and Sons New York) and analytical approaches have been adopted to evaluate the slope stability, based on the geotechnical and monitoring data and the geometrical and geological features of the slope. 相似文献
5.
基于青藏高原楚玛尔河地区青藏公路里程K2968+200断面浅层地温监测数据（地表下5 cm）,拟合了边界温度的回归方程,分析了公路路基及铁路路基两侧表层温度的特征.同时对路基坡面温度和理论辐射值的相关性进行了分析.结果表明：边界温度回归方程拟合程度较高,可作为冻土路基数值模拟温度边界选取的参考依据;监测断面公路和铁路路基都表现出显著的阴阳坡差异,公路左右坡面冬季温度差异达11.49℃,年均值差4.77℃,冬季铁路路基左右坡脚温度差异达到5.34℃,年均值差3.33℃,天然地表与气温的差值为5.2℃;根据融化与冻结n系数,位于阳坡一侧的冻结n系数较低且融化n系数大,表现为吸热;阴坡一侧冻结n系数较大,整体呈现出放热效应;路基边坡太阳理论辐射与温度变化趋势基本一致. 相似文献
6.
2008年5月12日发生在汶川的8．0级地震,震中位于龙门山断裂带的映秀-北川断裂上。通过对震区的现场调查,这次地震在极震区造成的地表破裂带主要在龙门山断裂带的中央断裂即映秀-北川断裂和前山断裂即彭县-灌县断裂。通过调查发现,极震区的地表断层产状多为北东走向,以逆冲运动为主。而在极震区以北的四川平武、青川和陕西宁强等余震分布区,地表也发生破裂,但规模和产生的地表变形明显减弱,主要以地裂缝等地质灾害形式表现。 相似文献
7.
A probabilistic 3-D slope stability analysis model (PTDSSAM) is developed to evaluate the stability of embankment dams and their foundations under conditions of staged construction taking into consideration uncertainty, spatial variabilities and correlations of shear strength parameters, as well as the uncertainties in pore water pressure. The model has the following capabilities: (1) conducting undrained shear strength analysis (USA) and effective stress analysis (ESA) slope stability analysis of staged construction, (2) incorporation of field monitored data of pore water pressure, and (3) incorporation of increase of undrained shear strength with depth, effective stress, and pore water pressure dissipation. The PTDSSAM model is incorporated in a computer program that can analyze slopes located in multilayered deposits, considering the total slope width. The main outputs of the program are the geometric parameters of the most critical sliding surface (i.e., center of rotation/radius of rotation and critical width of failure), mean 2-D safety factor, mean 3-D safety factor, squared coefficient of variation of resisting moment, and the probability of slope failure. The program is applied to a case study, Karameh dam in Jordan. Monitored data of induced pore water pressure in the dam embankment and soft foundation were gathered during dam construction. The stability of Karameh dam embankment and foundation was evaluated during staged construction using deterministic and probabilistic analysis. Foundation stability was evaluated based on the monitored data of pore water pressure. The study showed that the mean values of the corrective factors which account for the discrepancies between the in situ and laboratory-measured values of soil properties and for the modeling errors have significant influence on the 2-D safety factor, 3-D safety factor, slope probability of failure, and on the expected failure width. The degree of spatial correlation associated with shear strength parameters within a soil deposit also influences the probability of slope failure and the expected failure width. This correlation is quantified by scale of fluctuation. It is found that a larger scale of fluctuation gives an increase in the probability of slope failure and a reduction in the critical failure width. 相似文献
8.
Occurrences of landslide are most common and critical issue in North-East India. The various types of slope failures have been affected most part of slopes and road section between Malidor to Sonapur area (approx 30 Km) along NH-44 within Jaintia hills district, Meghalaya, India. These slope failures causes considerable loss of life and property along with many inconveniences such as disruption of traffic along highways. The unscientific excavations of rock slopes for road widening or construction purposes may weaken the stability of the slopes. The rocks exposed in the area are highly jointed sandstone and shale of Barail Group of Oligocene age. The Sonapur landslide is most dangerous and destructive rock fall-cum debris flow. The present study includes the kinematic analysis of the slope to assess the potential failure directions as the rocks are highly jointed in some parts of road cut sections. The continuous slope mass rating (CSMR) technique has been applied for slope stability analysis at five vulnerable locations. Kinematic analysis indicates mainly wedge type of failure along with few toppling and planar failures. These failure required immediate treatment to prevent the slide and long term stability of the slope. 相似文献
9.
基于区域地震台网的数字化波形资料,使用ISOLA方法对2019年5月18日吉林松原 M5.1地震进行矩张量反演,研究地震的震源机制,并且收集了地震序列中 ML2.5以上地震的震源机制解,采用FMSI（focal mechanism stress inversion）方法反演震中区构造应力场。结果显示：松原 M5.1地震的矩震级为4.9,矩心深度为6 km,双力偶分量为91.5%,主压应力 P轴方位角、倾角分别为76°和3°,主张应力 T轴方位角、倾角分别为166°和16°,震源机制解显示典型的构造地震特征;震中区构造应力场理论应力轴 σ1方位角、倾伏角分别为88.0°和0.9°, σ2方位角、倾伏角分别为178.2°和9.6°, σ3方位角、倾伏角分别为352.5°和80.4°,这一结果与区域构造应力场一致。推断认为区域构造应力场触发了2019年松原 M5.1地震活动,地震震源机制解的北西向节面与震中区附近的第二松花江断裂现今活动性质完全一致,认为第二松花断裂可能是松原 M5.1地震的发震断层。 相似文献
10.
风流场对于局地条件下地-气能量交换过程与强度影响显著,同时也是多年冻土区对流调控类冷却路基的关键环境边界。结合现场监测与数值模拟,对高海拔冻土路基周边风流场进行特征区划研究并考察路基高度的影响。结果表明：坡前扰动区为低风速区,3 m路基高度条件下迎风坡坡脚0.5~2.0 m高度范围内风速约为环境风速的30%。路基上部为高风速区,迎风坡路肩风速明显大于环境、路面中部及背风坡风速。背风坡坡后扰动区为低风速区,靠近坡脚区域受气流辐散效应作用形成涡旋区,整体风速仅为环境风速的30%。涡旋区水平范围随路基高度增加呈线性增加,3 m路基高度条件下涡旋区水平范围约为12 m。分离式路基即两幅路基并行条件下,受前幅路基影响后幅路基坡前风速下降明显,以两幅路基坡前风速差值不超过环境风速的10%（0.35 m·s -1）为标准,3 m路基高度条件下两幅路基最小间距为60 m。因此,在路基工程的修建过程中为减少路基间的遮挡所造成的两幅路基间的对流换热强度差异,分离式对流换热类冷却路基的现场修建间距应不低于60 m。 相似文献
11.
Successive applications of two-dimensional circular slip limit equilibrium analysis of slices have been made to the three sections of the Cox's Bazar Coastal Cliff. These three sections have been found to be stable (S), quasistable (QS), and unstable (U) with factors of safety (Fs) of 1.269 ± 0.01, 1.13 ± 0.0504, and 1.01 ± 0.058, respectively. In the quasistable and unstable sections, the slopes suffered shallow slidings with slip circles parallel to the surface of slopes.The main causes of these slidings are steepness of slopes, lack of vegetation cover, erosion of toe accumulations by run-off water and waves during high tides. The influence of the slope geometry and the material's strength properties of slopes on safety factors are evaluated. The steeper cliffs reach an unstable condition faster than the more gentle cliffs as their heights change by an equal amount. Again, the high cliffs reach an unstable condition faster than the lower cliffs as slope inclinations change by an equal amount. The safety factor increases with a corresponding increase of friction angle ( ø°) and vice versa.Abbreviations BK
Bahar chara to Kalatali chara
- KR
Kalatali chara to Reju khal
- RI
Reju khal to Boro Inani khal
- Fs
Factor of Safety
- S
Stable
- QS
Quasistable (semistable)
- US
Unstable 相似文献
12.
全球变暖、极端天气频发,引发的地质灾害对自然生态环境和人类生产生活造成了很大的影响。尤其对气候变化较为敏感的高温（年平均地温>-1 °C）和高含冰量多年冻土区,气候变暖以及人类活动导致的冻融地质灾害日益频繁。冻土退化条件下,土体结构和物理力学性质发生改变,黏聚力和抗剪强度降低,造成多年冻土区斜坡发生滑坡、崩塌、泥流等灾害。斜坡失稳加剧了多年冻土区脆弱生态环境的恶化,同时对建（构）筑物安全运营产生威胁。与非冻土区相比,多年冻土区斜坡稳定性研究主要针对高含冰量斜坡段,斜坡失稳模式主要以热融滑塌和活动层滑脱为主。热融滑塌由斜坡段地下冰暴露融化引起,而活动层滑脱产生的原因是冻土融化导致土体孔隙水压力过大,形成的超孔隙水压力降低了土体强度,造成斜坡失稳。此外,多年冻土区斜坡失稳模式还包括融冻泥流、崩塌以及蠕变滑坡等。通过综述近期多年冻土区斜坡稳定性研究进展,概括了多年冻土区斜坡失稳的模式、特征、影响因素、失稳机理、分析方法及防治措施等,并对未来多年冻土区斜坡失稳的研究重点提出建议。 相似文献
13.
Embankment slopes composed of spatially variable soils have a variety of different failure modes that are affected by the correlation distances of the material properties and the geometry and total length of the slope. This paper examines the reliability of soil slopes for embankments of different length and uses parallel computing to analyse very long embankments (up to 100 times the embankment height) for a clay soil characterised by a spatially varying undrained shear strength. Based on a series of analyses using the 3D random finite element method (RFEM), it is first shown that the reliability of slopes of various length can be efficiently computed by combining simple probability theory with a detailed 3D RFEM analysis of a representative shorter slope of length 10 times the slope height. RFEM predictions of reliability indices for longer slopes are then compared with results obtained using Vanmarcke's (1977a) simplified 3D method and Calle's (1985) extended 2D approach. It is shown that these methods can give significantly different results, depending on the horizontal scale of fluctuation relative to the slope length, with RFEM predicting a lower slope reliability than the Vanmarcke and Calle solutions in all cases. The differences in the solutions are evaluated and attributed to differences in the assumed and computed failure surface geometries. 相似文献
14.
The road widening carried out along National Highway-40, a strategic road corridor of north-eastern India, to ease the traffic snarls for geopolitical developments in the region. The newly exposed in situ soil slopes along National Highway-40 are on the verge of shear instability, and slope failures occur due to heavy earth cuttings. As a consequence, the road corridor witnesses several geotechnical failures during rainy seasons. The blasting activities initiated and propagated the soil creeps and falls resulting road blockades. Even a small rain shower is enough to undercut and uproot trees and transport boulders and surrounding earth materials up to the corridor. Besides, landslides are also prone to damage demographic areas and settling house units, thus invites for preventive measures towards hill slope management as these slopes make the highway corridor unsafe to the commuters. Therefore, the present study is aimed to investigate the stability of the hill cut soil slopes and to suggest possible stabilisation measures. The study also highlighted that steep soil slopes with high moisture content are prone to landslides mainly due to infiltration, and water flows on the slopes during high and prolonged rainfall. The highly plastic soils rich in silt and clay size particles with high moisture content cause soil/debris slide and flow. The numerical modelling of slopes using Fast Lagrangian Analysis of Continua (FLAC) codes (version 4.0) indicates failures in excavated high angle cut slopes. The re-excavation and benching of unstable slopes with geonets or bionets or jute matting to promote vegetation growth were suggested as stabilisation measures by field investigation, laboratory studies and numerical analysis of slopes. 相似文献
15.
为研究坡顶加载条件下黏性土坡的承载特性和变形规律,进行了素土坡和土钉加固土坡的加载离心模型试验。测量了土坡的承载和变形过程。通过对比两种土坡的承载特性和变性规律,土钉的加固作用体现在：限制了土坡向坡面方向的位移,使土坡的承载能力得到了明显提高;在加固土坡内形成的土钉影响区域改善了加载底板边缘处的薄弱程度;增大了土坡中上部土体的竖向压缩变形,减小了剪切变形,增强了土坡的稳定性。土坡上部土钉的加固效果随着坡顶荷载的增大而越明显;土坡中下部土与土钉的相互作用越靠近坡面越强 相似文献
16.
To understand the mechanism of the earth structure damage, a wide range of investigations along roads in seismic hazard areas
have been carried out after the 2008 Wenchuan earthquake. In this paper, the results from 41 roads investigated are presented,
and the 41 roads are located in 7–11 intensity zones and consist of rural/county roads, province roads and state roads in
Sichuan province. According to the investigation, the types of damaged slopes and retaining walls are classified and statistical
analyses are performed. In the statistical analyses, various impact factors to seismic slope and retaining wall damage were
studied, such as slope inclination, height of slope and retaining wall, site conditions, and seismic intensity. In addition,
some relationships were developed, including the quantity of damaged slopes with slope inclination and height, the angle between
route and fault rupture directions, and site conditions. Finally, some reasonable suggestions are put forward on the designs
and constructions of slopes and retaining walls when they are subject to seismic activity. 相似文献
17.
This study examines the effect of loss of apparent cohesion from rainwater infiltration upon the stability of partly saturated, allophanic soil slopes of Dominica (West Indies). The parent material of the Dominican allophanic soils are the andesitic and dacitic volcanic rocks from ten volcanic centres of mainly Pleistocene age. Although simplifying assumptions are made to assess the depth of wetting front and magnitudes of true and apparent cohesion values of the partly saturated allophanic soils, certain inferences of practical significance emerge from the study. Matric suction contributes to the effective stress of unsaturated soils and increases the shear strength of these soils by imparting them an apparent cohesion strength component. This apparent cohesion strength component of the partly saturated Dominician allophanic soils is considered to be related to the matric suction term (ua−uw) by a parabolic relationship. The partly saturated allophanic soil slopes of Dominica would invariably fail from loss of apparent cohesion upon saturation of the soil mantle by the infiltrating water front only if (a) the average slope angle (β) is greater than or equal to the drained shear strength parameter of the unsaturated soil (Φd) (slopes with β ≥ Φd are referred to as category 1 slopes in this study) and (b) the drained cohesion parameter (cd) belonging to the partly saturated soil of the category 1 slope is mainly contributed by matric suction induced apparent cohesion (capp) and contribution from true cohesion (c′) is absent. However, the possibility of the category 1 slopes (for the case 1 situation) failing in the saturated condition from effective stress reduction due to rise in ground water table is shown to be an unfeasible proposition. In contrast, for the case 1 situation, the partly saturated category 2 slopes (β < Φd) are insusceptible to failure from reduction in effective stress due to loss of matric suction but fail in the saturated condition from effective stress reduction due to rise in ground water table. If the allophanic soils were to possess a sufficient magnitude of true cohesion (c′), even the partly saturated category 1 slopes possessing slope angles (β) much in excess of their Φd values (β − Φd = 15.1°) would remain stable upon total elimination of the matric suction induced cohesion. However, partly saturated category 1 slopes possessing a true cohesion component and insusceptible to failure from reduction in effective stress upon loss of matric suction, invariably fail in the saturated condition from reduction in effective stress due to rise in ground water table. Using the methodology developed in this study, two previously reported case histories pertaining to rain induced translational landslides in the residual soil areas of Brazil are re-examined and the results obtained in this study are found to be in agreement with the findings of the previous researchers. 相似文献
18.
Rockfall susceptibility has been analysed in mountain cliffs of the Cantabrian Range, North Spain. The main aim of this analysis has been to build a predictive model of rockfall activity from a low number of environmental and geological variables. The rockfall activity has been quantified in a GIS. The cartographic information used shows the spatial distribution of all the recent talus screes as well as their associated source areas in the rock-slopes. The area relation At/Ar ( recent talus scree polygon/source basins) in the rock slopes has been used as the rockfall activity indicator. This relation has been validated in 50 pilot rock-slopes and compared with the relation number of recent rock fragments/source basin, obtained from field work. The environmental factors causing rockfall depend on the rock slope situation, and these are: altitude and sun radiation on the rock cliff. The geological factors considered are: lithology, relative position of the main discontinuities with respect to the topographic surface and two morphologic parameters: the roughness and slope gradient. A logistic regression analysis has been applied to a population of 442 limestone and quartzite rock cliffs. The dependent variable is the rockfall activity indicator, which allows the definition of two classes of rock cliff units: low and high activity. The independent variables are altitude, sun radiation (equinox radiation, summer solstice radiation, winter solstice radiation), slope roughness, slope gradient,anisotropy and lithology. Results suggest that it is possible tobuild a valid cartographic predictive model for rockfall activity in mountain rock cliffs from a limited number of easily obtainable variables. The method is especially applicable in massive rock slopes or in regions with uniform rock mass characteristics. 相似文献
19.
Previous theoretical considerations on the chemical U---Th-total Pb dating method failed to distinguish between thorogenic and uranogenic lead. However, it can be shown that the data points are located on a plane in the three-dimensional ThO 2, PbO, UO 2 space. The calculation of the best-fit plane yields a slope in the ThO 2---PbO and UO 2---PbO coordinate projections, and an initial PbO value. From the two slopes, Th/Pb- and U/Pb-ages can be calculated independently. The method described in this paper is applied to monazites from the Hercynian G4-granite of the Fichtelgebirge (Germany). Th/Pb- and U/Pb-ages were calculated at 323 ± 20 Ma and 304 ± 15 Ma, respectively. The intercept value close to zero indicates that no significant amounts of common lead are present in the monazites studied. 相似文献
20.
Horizontal drains have been commonly used in stabilising unsaturated residual soil slopes. This study examines the effectiveness of horizontal drains in stabilising residual soil slopes against rainfall-induced slope failures under a tropical climate. The study includes field instrumentation at two residual soil slopes complemented with a parametric study relating to drain position. Field monitoring results indicate that rainfall infiltration is limited to a certain depth below which infiltration becomes insignificant. This zone tends to be unsuitable for horizontal drains. Horizontal drains were found to be most effective when located at the base of a slope. The parametric study indicated conditions under which horizontal drains are effective or ineffective in improving the stability of a slope. It was also found that horizontal drains have little role in minimising infiltration in an unsaturated residual soil slope. Benefits of using horizontal drains can be obtained through the lowering of the water table. 相似文献
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