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111.
The study proposes geological evolution models for the cliff slopes of the two Italian towns of Orvieto (Umbria) and Radicofani
(Tuscany). The models were validated by the use of a stress–strain numerical modelling, implemented by the finite-difference
code FLAC 5.0. The numerical modelling was approached in a sequential way, by assuming specific stiffness values related to
the evolutionary stages. For this purpose, unconventional laboratory tests were performed aiming at reproducing the stress
path related to the geological evolution model, using standard equipment for CID triaxial testing. The geological evolution
models infer that deformation in both cases is driven by stress reduction. At the Orvieto plateau, stress reduction is induced
by stress relief involving a tuff plate; in the case of Radicofani, stress reduction is due to stress release in consequence
of lateral erosion of clay. Numerical simulations refine the lithotechnical zoning of the two investigated slopes, introducing
a stress–strain criterion in addition to the conventional geological and geomechanical ones. 相似文献
112.
Antecedent rainfall and short-term intense rainfall both contribute to the temporal occurrence of landslides in British Columbia. These two quantities can be extracted from the precipitation regimes simulated by climate models. This makes such models an attractive tool for use in the investigation of the effect of global warming on landslide frequencies.In order to provide some measure of the reliability of models used to address the landslide question, the present-day simulation of the antecedent precipitation and short-term rainfall using the daily data from the Canadian Centre for Climate Modelling and Analysis model (CGCM) is compared to observations along the south coast of British Columbia. This evaluation showed that the model was reasonably successful in simulating statistics of the antecedent rainfall but was less successful in simulating the short-term rainfall.The monthly mean precipitation data from an ensemble of 19 of the world's global climate models were available to study potential changes in landslide frequencies with global warming. Most of the models were used to produce simulations with three scenarios with different levels of prescribed greenhouse gas concentrations during the twenty-first century. The changes in the antecedent precipitation were computed from the resulting monthly and seasonal means. In order to deal with models' suspected difficulties in simulating the short-term precipitation and lack of daily data, a statistical procedure was used to relate the short-term precipitation to the monthly means.The qualitative model results agree reasonably well, and when averaged over all models and the three scenarios, the change in the antecedent precipitation is predicted to be about 10% and the change in the short-term precipitation about 6%. Because the antecedent precipitation and the short-term precipitation contribute to the occurrence of landslides, the results of this study support the prediction of increased landslide frequency along the British Columbia south coast during the twenty-first century. 相似文献
113.
Jean-François Oehler Jean-François Lénat Philippe Labazuy 《Bulletin of Volcanology》2008,70(6):717-742
This work presents the first exhaustive study of the entire surface of the Reunion Island volcanic system. The focus is on
the submarine part, for which a compilation of all multibeam data collected during the last 20 years has been made. Different
types of submarine features have been identified: a coastal shelf, debris avalanches and sedimentary deposits, erosion canyons,
volcanic constructions near the coast, and seamounts offshore. Criteria have been defined to differentiate the types of surfaces
and to establish their relative chronology where possible. Debris avalanche deposits are by far the most extensive and voluminous
formations in the submarine domain. They have built four huge Submarine Bulges to the east, north, west, and south of the
island. They form fans 20–30 km wide at the coastline and 100–150 km wide at their ends, 70–80 km offshore. They were built
gradually by the superimposition and/or juxtaposition of products moved during landslide episodes, involving up to several
hundred cubic kilometers of material. About 50 individual events deposits can be recognized at the surface. The landslides
have recurrently dismantled Piton des Neiges, Les Alizés, and Piton de La Fournaise volcanoes since 2 Ma. About one third
are interpreted as secondary landslides, affecting previously emplaced debris avalanche deposits. On land, landslide deposits
are observed in the extensively eroded central area of Piton des Neiges and in its coastal areas. Analysis of the present-day
topography and of geology allows us to identify presumed faults and scars of previous large landslides. The Submarine Bulges
are dissected and bound by canyons up to 200 m deep and 40 km long, filled with coarse-grained sediments, and generally connected
to streams onshore. A large zone of sedimentary accumulation exists to the north–east of the island. It covers a zone 20 km
in width, extending up to 15 km offshore. Volcanic constructions are observed near the coast on both Piton des Neiges and
Piton de la Fournaise volcanoes and are continuations of subaerial structures. Individual seamounts are present on the submarine
flanks and the surrounding ocean floor. A few seem to be young volcanoes, but the majority are probably old, eroded seamounts.
This study suggests a larger scale and frequency of mass-wasting events on Reunion Island compared to similar islands. The
virtual absence of downward flexure of the lithosphere beneath the island probably contributes to this feature. The increased
number of known flank–failure events has to be taken into consideration when assessing hazards from future landslides, in
particular, the probability of landslide-generated tsunamis.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
114.
115.
Mohanned S. Al-Sheriadeh Abdallah I. Husein Malkawi Ashraf Al-Hamdan Nabil S. Abderahman 《Engineering Geology》2000,56(3-4):361-372
With a capacity of 86 MCM, King Talal Reservoir is considered a major water supply in Jordan. It was built exclusively to irrigate the land in the Jordan Valley. Unexpectedly, the design capacity of the reservoir was confronted by the elevated sediment inflows during and after the construction of the Irbid–Amman Highway in 1987. Since then the annual sediment inflow measured at the mouth of the reservoir was higher than expected in a similar year. Notably, the over-wet season of 1991/2, as a result of six major landslides along the highway, registered the highest sediment inflow into the reservoir. In the present work the fractional contribution of these landslides to total sediment yield at the reservoir was evaluated. The evaluation was made by applying the well-known erosion model, AGNPS (Young et al., USDA Conservation Research Report 35, 1987). To calibrate the model, it was successively applied from 1980/1 to 1990/1 on the measured sediment data before the occurrence of landslides. With a slight tune-up of some of the King Talal watershed erosion variables, fairly good agreement was obtained in some years. However, the disagreement noticed in other years might be attributed to some conservation measures practised in the watershed. Because the serious landslides occurred in the wet season of 1991/2, the model was run for the two scenarios in this year: with and without landslides. The difference in results represents the contribution of landslides to sediment yield at the reservoir. It is concluded, based on these results, that landslides, if continued without control, will definitely jeopardize the design capacity of the reservoir. 相似文献
116.
Landslides associated with the colluvial soils overlying the Natal Group in the greater Durban region of Natal, South Africa 总被引:3,自引:1,他引:2
In the last 25 years, many of the landslides that have occurred in the greater Durban region have been associated with the
colluvial soils overlying the Natal Group, most of which occurred during the very heavy rains of September 1987. Subsequently,
a very heavy rainfall event in February 1999 also gave rise to landslides. In fact, prior to 1987 these colluvial soils were
considered relatively stable. A critical precipitation coefficient has been developed which included the cumulative precipitation
up to a landslide event. In addition, an attempt has been made to establish a threshold value for triggering of landslides
for the colluvial soils from a study of pluviometric data. The results indicate that when a rainfall event exceeds 12% of
the mean annual rainfall, small-scale landslides are likely to occur. When a rainfall event is greater than 16% of the mean
annual rainfall, a moderate number of landslides take place. Major landslides are associated with rainfall events with intensities
in excess of 20% of the mean annual precipitation. An example of a landslide which occurred on the Natal Group due to construction
operations is provided, as well as an account of those which took place during September 1987. In the latter case, most of
the slides took the form of mudflows and were responsible for some of the worst damage which has occurred in the Durban region.
The colluvial soils involved were relatively thin and therefore became quickly saturated by the heavy rainfall. In some places
the situation was further aggravated by liquefaction of the soils.
Received: 15 June 1999 · Accepted: 30 August 1999 相似文献
117.
《地学前缘(英文版)》2020,11(4):1107-1121
This study proposed a random Smoothed Particle Hydrodynamics method for analyzing the post-failure behavior of landslides,which is based on the Karhunen-Loeve(K-L) expansion,the non-Newtonian fluid model,and the OpenMP parallel framework.Then,the applicability of this method was validated by comparing the generated random field with theoretical result and by simulating the post-failure process of an actual landslide.Thereafter,an illustrative landslide example was created and simulated to obtain the spatial variability effect of internal friction angle on the post-failure behavior of landslides under different coefficients of variation(COVs) and correlation lengths(CLs).As a conclusion,the reinforcement with materials of a larger friction angle can reduce the runout distance and impact the force of a landslide.As the increase of COV,the distribution range of influence zones also increases,which indicates that the deviation of influence zones becomes large.In addition,the correlation length in Monte Carlo simulations should not be too small,otherwise the variation range of influence zones will be underestimated. 相似文献
118.
滑坡位移预测预报是滑坡防灾减灾的重要组成部分,提高滑坡位移预测的准确性与精确度是该项研究的重点与难点。本文在滑坡位移预测中考虑了监测样本的离群值,通过忽略、指定与修正离群值3种方式,研究滑坡位移预测样本离群值的最优处理方式。以三峡库区朱家店滑坡为例,基于ARIMA(p,d,q)模型,分别对累积位移与位移速率时间序列开展了预测研究。研究结果表明:修正离群值的预测结果介于忽略和指定离群值两者之间,更适用于存在监测离群值的滑坡位移预测;对于ARIMA模型,更适合采用位移速率进行预测预报;使用位移速率时间序列ARIMA(1,0,1)并修正离群值的预测结果为:2016年和2017年6月份滑坡前缘GP3"阶跃"位移分别为79. 0 mm和70. 2 mm,截止2017年8月,GP3累积位移将达1647. 7 mm。 相似文献
119.
由自然产生和人类活动引发的滑坡灾害在世界范围内都较普遍,其对人民的生命和财产安全构成了严重威胁,急需对其进行治理。以四川省石棉县新民乡科落头滑坡为例,在分析滑坡形成机理的基础上,进行了设计与施工探讨,为同类滑坡治理提供借鉴。 相似文献
120.
G.O. Jenkins C. Foster P.M. Hopson 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(5):906-922
The Cretaceous and Palaeogene sedimentary rocks that crop out on the Isle of Wight are highly prone to landsliding and the island offers an important field laboratory wherein to investigate a number of the different types of failure. Many of these landslides represent a significant engineering hazard, with several urban areas requiring remedial work and planning constraints (e.g. The Undercliff and Seagrove Bay) to aid development. Previous studies have thoroughly investigated the major landslides in the Undercliff area around Ventnor and presented a mechanism for that massive failure. This overview of the landslides throughout the Isle of Wight by the British Geological Survey was completed as part of the multidisciplinary survey of the surface geology, structure, geophysical response and offshore interpretations of the island between 2007 and 2010. The survey has collected new observational data on the extensive coastal landslides, as well as the distribution, nature and mechanism of failure of the lesser-studied inland examples. 相似文献